Target Quadrant Residence Time Research Articles

Relationship between gut microbiota and its metabolite dysregulation and postoperative cognitive dysfunction in elderly male C57BL/6J mice after laparotomy exploration

Objective: To explore the relationship between gut microbiota and its metabolite dysregulation and postoperative cognitive dysfunction in elderly male C57BL/6J mice after laparotomy exploration. Methods: A total of 48 specific pathogen-free (SPF) male C57BL/6J mice, aged 16-17 months, were divided into two groups by random number table method: control group (n=24) and operation group (n=24). Mice in the operation group were induced with 1.4% isoflurane for 15 minutes, followed by a 10 minutes exploratory laparotomy anesthetized with 1.4% isoflurane and 100% oxygen, and anesthesia continued for 2 hours after surgery. Mice in control group were put in 100% oxygen for 2 hours. Feces and venous blood samples of both groups were collected 48 hours after surgery. Changes in the abundance and diversity of intestinal bacteria in the feces were detected by 16S rDNA gene sequencing. Functional changes of fecal metabolic profiles were detected by liquid chromatography tandem mass spectrometry (LC/MS) metabolomics and differential metabolite functions were analyzed. The serum level of interleukin (IL)-6, IL-1β and tumor necrosis factor-α (TNF-α) were detected by Enzyme-linked immunosorbent assay (ELISA). The cognitive function of the mice was detected by Morris water maze test 3 days after operation. Results: The postoperative escape latency of mice in control group and operation group was (22.0±4.9) and (35.0±5.1) s, and the target quadrant residence time was (26.0±3.7) and (16.0±2.9) s, respectively. Compared with the control group, the postoperative escape latency of mice in the operation group was prolonged (P=0.035), and the residence time in the target quadrant was reduced (P=0.006). The difference of intestinal flora between the two groups was comparable. The expression levels of Escherichia coli, shigella and clostridium in the operation group were up-regulated, while the expression levels of rumen bacteria and butyricobacteria were down-regulated. Fecal metabolic profiles of mice in control group and operation group were obtained by LC/MS, and 14 and 21 different metabolites were screened in positive and negative ion modes, respectively. The different metabolites in positive ion mode were glutamic acid, 2-indoleic acid, kynuuric acid and glyceraldehyde. The negative ion pattern differential metabolites are methionine, aspartic acid, L-threonine, tyrosyl-threonine and 5-hydroxyindole-3-acetic acid. The identified differential metabolite pathways are mainly involved in amino acid, fatty acid and tryptophan metabolism and nucleotide synthesis. There were no significant differences in serum levels of IL-1β, IL-6 and TNF-α between the two groups (all P>0.05). Conclusion: The dysregulated changes of gut microbiota and its metabolites are correlated with the occurrence of postoperative cognitive dysfunction in elderly male C57BL/6J mice. Anesthesia and surgery alter the structure of mice intestinal bacteria on the level of abundance, and change the metabolic balance and feces metabolomic phenotype.

Ginsenoside Rg1 improved learning and memory ability and reduces neuronal apoptosis in epileptic rats through ERK/CREB/BDNF signal pathway

ObjectiveThis research was devoted to estimating the outcomes of ginsenoside Rg1 on learning and memory ability and neuronal apoptosis in epileptic rats through ERK/CREB/BDNF pathway. MethodsThe epileptic rats induced by lithium chloride were stochastically separated into model subgroup, ginsenoside Rg1 different dose subgroups. The ginsenoside Rg1 subgroups were given 20, 30 and 40 mg/kg ginsenoside Rg1 by gavage individually. Another 6 normal rats were selected as the control subgroup. The seizures of each subgroup were estimated. Morris water maze was utilized for estimating the changes of cognitive function changes of rats. The injury and apoptosis of hippocampal neurons in each subgroup were detected by Nissl and TUNEL assays. HE staining was applied for the structural and pathomorphological changes of hippocampal neurons detection. The oxidative stress level in hippocampus of rats was estimated by ELISA. DCFH-DA probe was applied for the changes of reactive oxygen species (ROS) in brain tissue detection. The Bcl-2, Bax, ERK, p-ERK, CREB, p-CREB and BDNF levels in cerebral cortex were estimated by western blot, and PD98059, a blocker of ERK pathway, was used to intervene. ResultsIn the control subgroup, Nissl bodies were abundant and evenly distributed, and cortical neurons were arranged neatly. In the model subgroup, the cytoplasmic staining of cortical neurons was insufficient and the arrangement of neurons was disordered. After treatment with ginsenoside Rg1, the morphology of neurons in the cerebral cortex was restored. The frequency of seizures, duration of seizures, Racine grade, escape latency, target quadrant residence time, MDA, TNF-α and ROS levels of cerebral cortex in the model subgroup boosted notablely versus the control subgroup. The frequency of crossing the original platform, the activity of SOD, the IL-10, p-ERK/ERK, p-CREB/CREB and BDNF levels in cerebral cortex were notablely lessened. The above-mentioned indexes in the ginsenoside Rg1 subgroup were notablely improved versus the model subgroup, and the three proteins levels in the PD98059 intervention subgroup were notablely lower. ConclusionGinsenoside Rg1 can improve cognitive dysfunction in epileptic rats, which may be concerned with ERK/CREB/BDNF pathway activation in cerebral cortex and lessening oxidative stress and inflammation.

Phosphate and tension homology-induced kinase 1/Parkin signaling mediates cognitive dysfunction in sepsis-associated encephalopathy through activation of hippocampal mitochondrial autophagy

To investigate the effects of gene of phosphate and tension homology (PTEN)-induced putative kinase 1 (PINK1)/Parkin pathway on hippocampal mitophagy and cognitive function in mice with sepsis-associated encephalopathy (SAE) and its possible mechanism. A total of 80 male C57BL/6J mice were randomly divided into Sham group, cecal ligation puncture (CLP) group, PINK1 plasmid transfection pretreatment groups (p-PINK1+Sham group, p-PINK1+CLP group), empty vector plasmid transfection control group (p-vector+CLP group), with 16 mice in each group. The mice in CLP groups were treated with CLP to reproduce SAE models. The mice in the Sham groups were performed laparotomy only. Animals in the p-PINK1+Sham and p-PINK1+CLP groups were transfected with PINK1 plasmid through the lateral ventricle at 24 hours before surgery, while mice in the p-vector+CLP group were transfected with the empty plasmid. Morris water maze experiment was performed 7 days after CLP. The hippocampal tissues were collected, the pathological changes were observed under a light microscope after hematoxylin-eosin (HE) staining, and the mitochondrial autophagy was observed under a transmission electron microscopy after uranyl acetate and lead citrate staining. The expressions of PINK1, Parkin, Beclin1, interleukins (IL-6, IL-1β) and microtubule-associated protein 1 light chain 3 (LC3) were detected by Western blotting. Compared with the Sham group, CLP group mice in Morris water maze experiment had longer escape latency, shorter target quadrant residence time, and fewer times of crossing the platform at 1-4 days. Under the light microscope, the hippocampal structure of the mouse was injured, the neuronal cells were arranged in disorder, and the nuclei were pyknotic. Under the electron microscope, the mitochondria appeared swollen, round, and wrapped by bilayer or multilayer membrane structures. Compared with the Sham group, CLP group had higher expressions of PINK1, Parkin, Beclin1, LC3II/LC3I ratio, IL-6 and IL-1β in hippocampus, indicating that sepsis induced by CLP could activated inflammatory response and caused PINK1/Parkin-mediated mitophagy. Compared with the CLP group, p-PINK1+CLP group had shorter escape latencies, spent more time in the target quadrant and had more number of crossings in the target quadrant at 1-4 days. Under the light microscope, the hippocampal structures of mice was destroyed, the neurons were arranged disorderly, and the nuclei were pyknotic. Under transmission electron microscope, swollen and rounded mitochondria and mitochondrial structure wrapped by double membrane or multilayer membrane structure were observed. Compared with the CLP group, the levels of PINK1, Parkin, Beclin1 and LC3II/LC3 ratio in the p-PINK1+CLP group were significantly increased [PINK1 protein (PINK1/β-actin): 1.95±0.17 vs. 1.74±0.15, Parkin protein (Parkin/β-actin): 2.06±0.11 vs. 1.78±0.12, Beclin1 protein (Beclin1/β-actin): 2.11±0.12 vs. 1.67±0.10, LC3II/LC3I ratio: 3.63±0.12 vs. 2.27±0.10, all P < 0.05], while the levels of IL-6 and IL-1β were significantly decreased [IL-6 protein (IL-6/β-actin): 1.69±0.09 vs. 2.00±0.11, IL-1β protein (IL-1β/β-actin): 1.11±0.12 vs. 1.65±0.12, both P < 0.05], suggesting that overexpression of PINK1 protein could further activate mitophagy and reduce the inflammatory response caused by sepsis. There was no statistically significant difference in the above pathological changes and related indicators between Sham group and p-PINK1+Sham group, CLP group and p-vector+CLP group. PINK1 overexpression can further activate CLP-induced mitophagy by upregulating Parkin, thereby inhibiting inflammation response and alleviate cognitive function impairment in SAE mice.

Protective effect of total saponins of ginseng stems and leaves (GSLS) on chlorpyrifos-induced brain toxicity in mice through the PTEN/PI3K/AKT axis.

Chlorpyrifos (CPF) is a class of toxic compounds which has been widely used in agriculture that can cause multi-organ damage to the liver, kidneys, testes, and nervous system. Currently, most studies on ginseng have concentrated on the roots and rhizomes, and less research has been conducted on the above-ground parts. Our laboratory found that ginseng stem and leaf total saponin (GSLS) features strong antioxidant activity. In this experiment, we selected different concentrations of CPF to induce hippocampal neuronal cell injury model in mice, conducted a cell survival screening test, and also selected appropriate concentrations of CPF to induce brain injury model in mice. CCK-8, flow cytometry, Elisa, Hoechst 33258 staining, Annexin V-FITC/PI staining, HE staining, Morris water maze, and qRT-PCR were adopted for detecting the effects of GSLS treatment on CPF-induced cell viability, mitochondrial membrane potential, reactive oxygen species (ROS) levels, Ca2+ concentration and GSLS treatment on CPF-induced brain injury and related signaling in mice, respectively. The effects of GSLS treatment on CPF-induced brain injury and the related signaling pathways in mice were examined. The results showed that GSLS at 60 μg/ml and 125 μg/ml concentrations elevated the viability of CPF-induced HT22 cells, increased mitochondrial membrane potential, depleted ROS, decreased Ca2+ concentration, and decreased apoptosis rate. Meanwhile, GSLS treatment significantly reduced CPF-induced escape latency in mice, elevated the number of entries into the plateau and effective area, increased the effective area and target quadrant residence time, as well as improved the pathological damage of mouse hippocampal neurons. The results of mouse brain sections demonstrated that GSLS treatment significantly increased SOD and CAT activities and lowered MDA accumulation in CPF-induced mice. qRT-PCR revealed that PTEN mRNA expression was significantly decreased with PI3K and AKT expression being significantly increased in GSLS-treated CPF-induced mice. Thus, the obtained results indicate that GSLS can effectively antagonize CPF-induced brain toxicity in mice through regulating PTEN/PI3K/AKT pathway.

Effects of total saponins from Trillium tschonoskii Maxim on vascular cognitive impairment and its mechanisms

Objective: To investigate neuroprotective effects of total saponins from Trillium tschonoskii Maxim (TST) on vascular cognitive impairment (VCI) rats through inflammatory body of the NOD-like body protein 3 (NLRP3) regulated by endoplasmic reticulum stress (ERS). Methods: SD rats were divided into sham-operated group (SHAM), model group (VCI, bilateral neck arterial ligation (BCCAO) method), TST intervention group (TST, 100 mg/kg), and positive group (donepezil hydrochloride, 0.45 mg/kg ), continuous administration for 4 weeks. The ability of learning and memory was evaluated by the morris water labor. The tissue pathological changes were observed by HE and NISSL staining. Western blot was used to detectendoplasmic reticulum-related proteins GRP78, IRE1, XBP1. Inflammasome-related proteins NLRP3, ASC, Caspase-1, IL-18, IL-1β. Results: Compared with the SHAM group, the escape latency of VCI group rats was prolonged significantly, and the number of times of crossing the platform and the percentage of target quadrant residence time were shortened (P＜0.01); The cells in the hippocampus of VCI rats were damaged, with obvious pyknosis, decreased number of neurons and damage of cell body structure; The endoplasmic reticulum and inflammatory corpuscle-associated proteins were increased in VCI group (P＜0.05 or P＜0.01). Compared with the VCI group, the TST group and the positive group had less time to search for the platform, and the ratio of the times of crossing the platform to the time in the target quadrant was longer (P＜0.05 or P＜0.01). There was no significant difference in the times of crossing the platform between the positive group and VCI group (P＞0.05); The cell damage, nuclear pyknosis and the number of neurons in TST and positive groups were significantly reduced; The endoplasmic reticulum associated proteins and inflammatory body associated proteins in TST group and positive group were decreased to different degrees (P＜0.05 or P＜0.01). Conclusion: TST has neuroprotective effects on VCI rats, and its mechanism may be related to the involvement of ERS in the regulation of NLRP3 inflammatory small bodies.

Effects of spicy leaves on cognitive function and apoptosis of hippocampal neurons in diabetic rats

Objective: To investigate the effects of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons in diabetic rats induced by streptozotocin (STZ). Methods: Fifty male SD rats were selected, and 10 rats were randomly selected as the control group. The other 40 rats were treated with STZ at the dose of 25 mg/kg by intraperitoneal injection. The 40 diabetic rats were randomly divided into model group, Moringa oleifera low-dose, medium-dose and high-dose group. The rats in Moringa oleifera groups were treated with Moringa oleifera at the doses of 2.0, 4.0 and 8.0 g/kg by gavage, the control group and model group were treated with the same amount of normal saline once a day, for 8 weeks. Morris water maze test was used to evaluate the learning and memory ability of rats. Pathological changes of hippocampal neurons and expressions of Bax, caspase-3 and bcl-2 protein in each group were observed by the sections were stained with HE staining and immunohistochemistry. Enzyme linked immunosorbent assay (ELISA) was used to detect tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in rat. Results: compared with the control group, the blood glucose of the model group was increased significantly (P＜0.01), and the blood insulin level was decreased significantly (P＜0.05); compared with the model group, the blood glucose values of Moringa oleifera groups were decreased significantly (P＜0.05, P＜0.01), and the blood insulin levels of middle and high dose Moringa oleifera group were increased significantly (P＜0.05, P＜0.01). There was no significant difference in FBG and INS among the three groups (P＞0.05). In Morris water maze test, compared with the model group, the latency of Moringa oleifera groups was significantly shorter (P＜0.05); the residence time in target quadrant of Moringa oleifera groups with different doses was significantly prolonged (P＜0.05). Compared with the model group, the contents of TNF - α, IL-6 and protein expression in low, medium and high dose groups of Moringa oleifera were decreased significantly (P＜0.05). HE staining and immunohistochemical staining results showed that Moringa oleifera medium dose group was positive, brown yellow, fine granular, compared with the model group. The number of neuronal apoptosis was significantly reduced in the middle dose group (53.21±7.19,P＜0.01); the protein expressions of Bax, caspase-3 and the ratio of Bax/Bcl-2 in hippocampus were significantly decreased in the middle dose group (P＜0.05). Conclusion: The mechanisms of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons may be related to regulating the protein expressions of Bax, Bcl-2 and Caspase-3, reducing the contents of inflammatory factors TNF-α and IL-6.

Effects of fine particulate matter on cognitive function and gut microbiota in adult male mice

To study the effects of fine particulate matter(PM_(2.5))exposure to cognitive function and intestinal flora abundance and diversity in adult male mice. The SPF grade male C57 BL/6 J mice with 8 weeks old were randomly divided into control group(NS group), PM_(2.5) exposure group(PM_(2.5) group), probiotic group(VSL#3 group) and PM_(2.5) + VSL#3 group(PMV group), with 8 mice in each group. The PM_(2.5) group and PMV group mice were exposed to PM_(2.5) using animal exposure system equipped with real-time PM_(2.5) concentration, and concentrated 6 times the outdoor PM_(2.5) concentration, 8 h every day, 5 d every week for 4 weeks. The VSL#3 group and PMV group mice were given VSL#3, 0.5 mL, 2×10~9 CFU/mL. After four weeks of exposure, feces from mice were collected for 16 s rRNA high-throughput sequencing, and the cognitive function was evaluated using Morris water maze and object recognition experiments. The escape latency of PM_(2.5) group in four-day training [(54.99±6.77) s, (41.21±9.98) s, (36.27±13.11) s, (30.01±14.80) s] were higher than that of NS group [(32.19±4.59) s, (20.50±6.77) s, (19.93±7.30) s, (16.94±9.91) s], and the difference were statistically significant(P&lt;0.05). The escape latency of PMV group on the first and second day of training [(39.02±6.23) s, (28.83±9.53) s] were lower than that of PM_(2.5) group(P&lt;0.05). The target quadrant residence time of mice in PM_(2.5) group [(18.30± 8.88) s] was lower than that in NS group and PMV group [(30.53±9.10) s, (30.00±10.61) s]. Compared with NS group(6.09±0.40), the shannon index of PM_(2.5) group and PMV group(5.05±0.65 and 5.46±0.52) were significantly reduced(P&lt;0.05). The target quadrant time was positively correlated with the relative abundance of Actinomyces(r=0.576, P&lt;0.05), and the recognition index was positively correlated with the relative abundance of Firmicutes(r=0.612, P&lt;0.05). PM_(2.5) could lead to cognitive dysfunction in mice, which is related to diversity and abundance of the intestinal flora. Probiotic can improve cognitive function.

Effect of operative trauma and multiple propofol anesthesia on neurodevelopment and cognitive function in developmental rats

To investigate the effect of multiple propofol anesthesia and operative trauma on neuroinflammation and cognitive function in development rats and its mechanism. A total of 104 13-day-old neonatal Sprague-Dawley rats were randomly divided into 4 groups with 26 rats in each group: control group was treated with saline q.d for propofol group was treated with propofol q.d for surgery group received abdominal surgery under local anesthesia and then treated with saline q.d for surgery with propofol group received propofol anesthesia plus abdominal surgery under local anesthesia with ropivacaine at d1, then treated with propofol q.d for At d2 of experiment, 13 rats from each group were sacrificed and brain tissue samples were taken, the concentration of TNF-α in hippocampus was detected with ELISA, the expression of caspase-3 and c-fos in hippocampal tissue was determined with immunohistochemical method, the number of apoptotic neurons in hippocampus was examined with TUNEL assay. Morris water maze test was used to examine the cognitive function of the rest rats at the age of 60 d, and the TNF-α concentration, caspase-3, c-fos expressions and the number of apoptotic neurons in hippocampus were also detected. Compared with control group, TNF-α concentration, caspase-3, c-fos expression and the neuroapoptosis in hippocampus increased significantly in other three groups (all <0.05). Compared with surgery group, propofol group and surgery with propofol group showed increased TNF-α level, caspase-3 and c-fos expressions and apoptotic cell numbers (all <0.05), but there was no significant difference between last two groups (all >0.05). Morris water maze test showed that there were no significant differences in swimming speed, escape latency, target quadrant residence time and crossing times among groups (all >0.05). TNF-α level, expressions of caspase-3 and c-fos and apoptotic cell numbers in hippocampus had no significant differences among the 4 adult rats groups (all >0.05). Abdominal surgery and multiple propofol treatment can induce neuroinflammation and neuroapoptosis in hippocampus of neonatal rats, however, which may not cause adverse effects on neurodevelopment and cognitive function when they grown up.

Effect of dexmedetomidine combined with etomidate on IL-17A and S-100β expression levels in rats with postoperative cognitive dysfunction.

The present study aimed to explore the effects of dexmedetomidine combined with etomidate on the expression levels of interleukin (IL)-17A and S-100β in rats with postoperative cognitive dysfunction (POCD). A total of 50 SD rats were randomly allocated into the control group, model group, etomidate group (Eto group), dexmedetomidine group (Dex group) and dexmedetomidine combined with etomidate group (Dex-Eto group). Inhalation anesthesia was used in all five groups. Apart from the control group, partial lobectomy was performed to construct a rat model of cognitive dysfunction. The rats of the model group received no intravenous anesthesia, except general anesthesia with intubation. Morris water maze test was performed before injection (T0), at the 1st day (T1), the 3rd day (T2) and the 5th day (T3) after operation to assess the memory ability of the rats. At the end of T3, the expression levels of IL-17A, S-100β, TNF-α, IL-6 and IL-1β in serum were detected by ELISA and the expression of NF-κB p65 by western blot analysis. Compared with the control group, the model group showed an increased escape latency and swimming distance, decreased number of times of crossing the platform and target quadrant residence time, and increased expression levels of IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65. Compared with the model group, the escape latency and swimming distance in the Dex, Eto and Dex-Eto groups were reduced, whereas the number of times of crossing the platform and the target quadrant residence time were increased. In addition, the expression levels of IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65 were decreased in the Dex, Eto and Dex-Eto groups, compared with the model group. Among the Dex, Eto and Dex-Eto groups, the escape latency and swimming distance in the Dex-Eto group were the shortest, the number of times of crossing the platform and the target quadrant residence time were the highest, and IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65 expression levels were the lowest. In conclusion, dexmedetomidine combined with etomidate can effectively improve POCD.

Effects of Vortioxetine on depression model rats and expression of BDNF and Trk B in hippocampus.

Effects of Vortioxetine on the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (Trk B) in hippocampus of depressive rats were investigated. Forty-five SD rats were randomly divided into three groups: model control, Vortioxetine and normal control group, with 15 rats in each group. The changes of body mass were recorded within 5 weeks, and the open field test, sugar water preference test and Morris water maze test were performed to evaluate the behavior and mental status of the rats. The expression of BDNF and Trk B in rat hippocampus was detected by enzyme-linked immuno sorbent assay. Compared with the model control group, the body mass, horizontal and vertical movement, sugar and water preference rate of the vortioxetine group in the 5th week were significantly higher than those of the model control group (P<0.05), and significantly lower than those of the normal control group (P<0.05). The escape latency of the Vortioxetine group within 4 days was significantly lower than that of model control group (P<0.05), but higher than that of normal control group (P<0.05). The target quadrant residence time of the Vortioxetine group was significantly lower than that of the model control group (P<0.05), but higher than that of the normal control group (P<0.05). Expression of BDNF and Trk B in the Vortioxetine group was significantly higher than that in the model control group (P<0.05), but lower than that of the normal control group (P<0.05). Collectively, Vortioxetine can effectively alleviate the symptoms of autonomous and exploratory behavior, and reduce the decrease of learning and memory in depressive rats. Vortioxetine can increase the expression of BDNF and Trk B in depressive rats and alleviate their depressive behavior.

Typical neurobehavioral methods and transcriptome analysis reveal the neurotoxicity and mechanisms of di(2-ethylhexyl) phthalate on pubertal male ICR mice with type 2 diabetes mellitus.

In the present study, the neurotoxicity and mechanisms of di-(2-ethylhexyl) phthalate (DEHP) exposure on pubertal normal (P-normal) and pubertal type 2 diabetes mellitus (P-T2DM) mice were investigated by typical neurobehavioral methods and transcriptome analysis. Pubertal male ICR mice were orally exposed to DEHP (0.18, 1.8, 18 and 180mg/kg/d) for 3weeks. In Open field test, DEHP significantly increased the time in central area staying and decreased the total distance and clockwise (CW) rotation of P-normal and P-T2DM mice. Morris water maze showed that DEHP significantly increased the latency in locating platform and decreased the original platform quadrant and residence time in target quadrant of P-normal and P-T2DM mice. Transcriptome analysis results revealed the effects of DEHP exposure on neural signaling pathway including biogenic amines neurotransmitters, nerve receptors, neurobiological processes, etc. Enzyme-linked immunosorbent assay (ELISA) and western blotting results showed that DEHP significantly decreased the contents of 5-HT, cAMP, GABA and Ca2+, the levels of CREB, phosphorylation of PKA, ERK1/2 and CREB, increased the levels of CaM and phosphorylation of CaMKII in P-normal and P-T2DM mice. Factorial analysis results showed that P-T2DM mice were more sensitive than those of P-normal mice. The potential neurotoxicity mechanism of DEHP may be synergistically mediated by the cAMP-PKA-ERK1/2-CREB signaling and the Ca2+ signaling pathway.

Effect and mechanism of dihydromyricetin on cognitive dysfunction in model rats with Alzheimer’s disease

Objective To explore the protective effect and mechanism of the dihydromyricetin (DHM) on cognitive dysfunction in Alzheimer’s disease (AD) rat model. Methods The AD model of rats was established by injecting Aβ1-42 oligomolymer into the hippocampus. According to the random number table, 30 successfully constructed AD model rats were divided into AD group, AD+ DHM1 group and AD+ DHM2 group, with 10 in each group.And the rats in the three groups were intraperitoneally injected with normal saline, 100 mg/kg DHM and 200 mg/kg DHM for 21 days, respectively.Another 10 rats with body mass matching were taken as the control group.Morris water maze was used to evaluate the spatial learning and memory ability of rats in each group, the expression of inflammatory cytokines were detected by Elisa, and the expressions of AMPK and SIRT1 proteins were detected by Western blot. Results Compared with the control group, the escape incubation period of rats in AD group was prolonged, and the difference was statistically significant (day 5 : (10.36±2.80)s, (22.40±2.98)s; t=-18.63, P<0.05). Compared with AD group, the escape latency of rats in AD+ DHM1 group and AD+ DHM2 group were shortened (day 5: AD+ DHM1 group (15.68±3.06) s, AD+ DHM2 group (18.85±3.22) s; t=10.65, 4.13, both P<0.05). Compared with AD group, rats in AD+ DHM1 group and AD+ DHM2 group had more crossing times ((1.87±0.76), (2.75±0.63) and (3.78±0.71); t=-6.86, -9.83, both P<0.05), and the target quadrant residence time were extended ((17.08±1.99) s, (16.33±4.33) s, (22.59±4.21) s; t= 28.5, 8.63, both P<0.05). Compared with the control group, the levels of IL-1β, IL-6 and TNF-α in the serum and hippocampus of the AD group were significantly increased (serum: t=4.98, 7.87, 5.43, all P<0.05; hippocampus: t=11.13, 30.50, 23.38, all P<0.05). Compared with the AD group, the levels of IL-1β, IL-6 and TNF-α in the serum and hippocampus of the AD+ DHM1 group and the AD+ DHM2 group were significantly decreased, the difference was statistically significant(serum: AD+ DHM1 group t=-4.13, -10.70, -9.22, AD+ DHM2 group t=-1.75, -3.63, -18.75, all P<0.05; hippocampus: AD+ DHM1 group t=-69.13, -15.13, -6.50, AD+ DHM2 group t=-10.25, -39.00, -8.00, all P<0.05). Compared with the control group, the expression of p-AMPK/AMPK protein and SIRT1 protein in the AD group were decreased.The expression of the two proteins in the AD+ DHM1 group and the AD+ DHM2 group were increased, comparing with those of AD group, and the difference was statistically significant(all P<0.05). Conclusion DHM exerts protective role in AD model rats, which may be related to the activation of AMPK/SIRT1 pathway and the inhibition of inflammatory response. Key words: Dihydromyricetin; Alzheimer’s disease; Cognitive function; AMPK; SIRT1; Inflammatory responses; Rat

The mechanism of lipopolysaccharide administration-induced cognitive function impairment caused by glucose metabolism disorder in adult rats.

ObjectiveThis essay aims to make investigation on the mechanism of glucose metabolism disorder and Lipopolysaccharide administration-induced cognitive function impairment in adult rats with surgery. Methods: Divide the objects, 40 male Sprague-Dawley rats at the age of 9 months, into 4 groups. Provide unilateral nephrectomy surgery and/or lipopolysaccharide intraperitoneal injection. Postoperative cognitive function evaluation would be tested by the Morris water maze. Rats with Postoperative Cognitive Dysfunction (POCD) were scanned to analyze the brain glucose metabolism by means of 18F-FDG PET/CT. Phosphatidylinositol 3-Kinase (PI3K), Protein Kinase β (AKT), Insulin Substrates Receptor-2 (IRS-2) and Glucose Transporter 4 (GLUT4) were detected as well. Data will be captured through gene expression in POCD rats via Quantitative Real-Time PCR (QRT-PCR). On the other side, Western Blot was used to measure the expression levels of IRS-2, p-IRS-2, p-PI3K, PI3K, p-AKT, AKT, GLUT4, and p-GLUT4. Results: During the Morris water maze test, the staging time (latency) of rats in each group was becoming short gradually as the training progressed. The incubation time of Day 5 of each group was shorter than that of Day 1 (P < 0.05). On the Day 3 after the surgery, the average target quadrant residence time of Group S+L (100 μg/Kg) was shorter, compared with Group C, L and S. Of which, the average number of perforation was reduced greater than that of Group C (P < 0.05). The average swimming speed of the groups is of no distinct difference (P > 0.05). After the operation, there was no great difference shown among the subjects (P > 0.05) in the average residence time of the target quadrant, the mean number of passages, and the mean swimming speed. On Day 3, the average latency of Group S+L (100 μg/Kg) was longer than Group C (P < 0.05) in the working memory test after the operation. The average latency of rats in Group L and S was showed longer than that in Group C, with tiny difference (P > 0.05). In the 7-Day working memory test, the average latency of the rats in Group L, S and S+L (100 μg/Kg) was obviously longer than that in Group C. Comparing to preoperative rats, POCD rats of Group S+L (100 μg/Kg) were scanned by 18F-FDG PET/CT three days later after the operation. Its SUVmax of the frontal and temporal lobe areas were decreased significantly (P < 0.05). However, difference degree was not significantly shown in the SUVmax between Group C and the preoperative rats (P > 0.05). In comparison with the gene expression of of Group C, the PI3K, IRS-2, AKT and GLUT4 mRNA genes are the key genes in the insulin signaling pathways of the hippocampus of the POCD rats. The expression level was reduced. The expression level of all protein of PI3K, IRS-2, GLUT4 and AKT in the POCD rats was of no great contrast with that in Group C. But for IRS-2 protein, the phosphorylation level has increased, and meanwhile decreased for AKT, PI3K and GLUT4 proteins (P < 0.05). Conclusions: Adult SD rats cognitive dysfunction model treated with unilateral nephrectomy combined and 100 μg/kg LPS intraperitoneal injection were led to abnormal both brain glucose metabolism and insulin expression. The proved phenomenal results signal pathway-related proteins PI3K, IRS-2, AKT and GLUT4. It reached the conclusion that surgical trauma, rather than anesthesia, leads to impaired cognitive function. PI3K, IRS-2, AKT, and GLUT4pathway of brain can be partial explanations of the pathogenesis of POCD.

Effect of rutaecarpine on Alzheimer's disease-like cognitive impairments induced by high glucose in rats

To investigate the effects of rutaecarpine on high glucose-induced Alzheimer's disease-like pathological and cognitive dysfunction and its mechanism in rats. Adult male SD rats were randomly divided into three groups (n=20): control group, high glucose group and rutaecarpine group. Rats in the control group were fed with conventional feed and tap water. The rats in the high glucose group were fed with conventional feed and 20% sucrose water. The rutaecarpine group was fed with fodder contain 0.01% rutaecarpine and 20% sucrose water. Morris water maze test was used to detect learning and memory and cognitive function of three groups rats after 24 weeks of feeding. Western blot analysis was used to detect tau protein at Thr205 and Ser214 sites in each group. Phosphorylation levels of GSK-3β in serine 9 site (S9-GSK-3β) and PP2A at cycline 307 site (Y307-PP2AC) were also detected. Immunohistochemistry further confirmed tau protein at Thr205 site in each group both in hippocampus and cortex. Compared with the control group, Morris water maze results showed that the latency of finding the hidden platform of the rats in high glucose group was increased significantly and the number of crossing platforms and the target quadrant residence time were significantly decreased (all P＜0.05). Immunohistochemistry showed that the phosphorylation level of tau protein at Thr205 site was significantly increased in the high glucose group compared with the control group, and the phosphorylation level of tau protein at Thr205 site in the rutaecarpine group was higher than that in the high glucose group. Western blot analysis showed that the phosphorylation level of tau protein in the high glucose group was significantly increased at Thr205 and Ser214 site compared with the control group, but the phosphorylation level of pS9-GSK-3β was significantly decreased (all P ＜0.05). Compared with the high glucose group, the latency of finding the hidden platform of the rats in rutaecarpine group was significantly decreased, and the number of crossing platforms and the target quadrant residence time were significantly increased (both P＜0.05). Compared with the high glucose group, the phosphorylation levels of tau protein at Thr205 and Ser214 sites showed a significant decrease, but the phosphorylation level of pS9-GSK-3β was significantly increased (all P＜0.05). Rutaecarpine can alleviate AD-like cognitive dysfunction induced by high glucose, possibly by enhancing pS9-GSK-3β phosphorylation, down-regulating GSK-3β activity, and thus reducing hyperphosphorylation of tau-associated sites.

Protective role of Dihydromyricetin in Alzheimer's disease rat model associated with activating AMPK/SIRT1 signaling pathway.

The aim of the present study was to understand the possible role of the Dihydromyricetin (DHM) in Alzheimer’s disease (AD) rat model through regulation of the AMPK/SIRT1 signaling pathway. Rats were divided into Sham group, AD group, AD + DHM (100 mg/kg) group and AD + DHM (200 mg/kg) group. The spatial learning and memory abilities of rats were assessed by Morris Water Maze. Then, the inflammatory cytokines expressions were determined by radioimmunoassay while expressions of AMPK/SIRT1 pathway-related proteins by Western blot; and the apoptosis of hippocampal cells was detected by TdT-mediated dUTP nick end labeling assay. AD rats had an extended escape latency with decreases in the number of platform crossings, the target quadrant residence time, as well as swimming speed, and the inflammatory cytokines in serum and hippocampus were significantly elevated but AMPK/SIRT1 pathway-related proteins were reduced. Meanwhile, the apoptosis of hippocampal cells was significantly up-regulated with decreased Bcl-2 and increased Bax, as compared with Sham rats (all P<0.05). After AD rats treated with 100 or 200 mg/kg of DHM, the above effects were significantly reversed, resulting in a completely opposite tendency, and especially with 200 mg/kg DHM treatment, the improvement of AD rats was more obvious. DHM exerts protective role in AD via up-regulation of AMPK/SIRT1 pathway to inhibit inflammatory responses and hippocampal cell apoptosis and ameliorate cognitive function.

Effect of IcarisideII on spatial learning and memory impairments and axonal regeneration in rats induced by chronic cerebral hypoperfusion

Objective To observe the effect of IcarisideⅡ(ICSⅡ) on spatial learning and memory impairments and axonal regeneration induced by chronic cerebral hypoperfusion(CCH) in rats. Methods 90 male SD rats were randomly divided into normal group, sham operation group, CCH group and ICSⅡ low, middle and high-dose treatment groups.The chronic cerebral hypoperfusion model was established by permanent bilateral common carotid artery occlusion.Then these rats in ICSⅡ low, middle and high-dose treatment groups were given ICSⅡ4, 8 and 16 mg/(kg·d) by gavage on the 1st day after modeling.There were 5 rats in every group at each observing time(4, 8 and 12 week). Morris water maze experiment was utilized to assess the escape latency and the target quadrant residence time while HE and immunohistochemistry analysis were applied to test the morphology change and expressions of GAP-43, MAP-2 and Nogo-A in hippocampal CA1. Results Compared with those of sham operation groups at 4, 8 and 12 week respectively, the escape latency in CCH group were significantly prolonged(40.02±4.95)s, (42.29±5.75)s, (53.68±6.14)s vs (26.43±2.68)s, (26.84±2.06)s, (31.53±4.12)s, P 0.05). Compared with those in 8 week and 4 week, the escape latency and the target quadrant residence time were prolonged and reduced with the expression of Nogo-A increased in all groups except normal group and sham operation group(P 0.05). However, there were no statistical significance of all indexes between 8 week and 4 week(P>0.05). Conclusion ICSⅡ can improve the spatial learning and memory in chronic cerebral hypoperfusion rats, which may be achieved by neuroprotective effects and reducing the expression of Nogo-A consequently promotes the regeneration of axons. Key words: IcarisideⅡ; Chronic cerebral hypoperfusion; Spatial learning and memory impairments; Axonal regeneration; Rat

Electroacupuncture can improve cognition in those with chronic cerebral hypoperfusion

Objective To investigate the effect of electroacupuncture (EA) on the cognitive function of rats with chronic cerebral hypoperfusion (CCH) and its possible mechanism. Methods Forty male Sprague-Dawley rats were randomly divided into a sham operation group of 10 and an operation group of 30. Permanent bilateral common carotid artery occlusion (BCCAO) was conducted to introduce a model of CCH in the operation group, which was further divided into a model group, an EA 4 w group and an EA 1 w group, each of 10. The EA 4 w group was given 2/100 Hz dilatational wave EA for 4 weeks, and the EA 1 w group was provided with the same EA for one week. A Morris water maze was used to assess the rats′ cognitive functioning, and a reverse transcription polymerase chain reaction (RT-PCR) was employed to detect the expression of JAK2/STAT3 mRNA in all the rats′ brains. Results Compared with the sham operation group, the rCBF in the operation group had decreased significantly after BCCAO, and it was significantly lower than before the operation. Compared with the model group, the escape latency improved significantly from the 3rd day in the EA 4 w group, and from the 5th day in the EA 1 w group. The targeted quadrant residence time of the EA 4 w group was prolonged significantly. JAK2/STAT3 mRNA expression decreased significantly only in the EA 4 w group. Compared with the EA 1 w group, the escape latency of the EA 4 w group had decreased significantly by the 5th day, with the target quadrant residence time significantly prolonged, and JAK2 mRNA had decreased significantly as well. Conclusion EA can improve cognition in CCH, at least in rats, and especially with early intervention. This may be achieved through inhibiting excessive activation of the JAK2/STAT3 pathway, reducing brain injury. Key words: Electroacupuncture; Cerebral hypoperfusion; Cognition; JAK2/STAT3 mRNA

Analysis of serum undercarboxylated osteocalcin level in rats with type 2 diabetes mellitus and the correlation with cognitive impairment.

The aim of the study was to investigate the correlation between the serum undercarboxylated osteocalcin (ucOC) level and the blood biochemistry and cognitive impairment in rats with type 2 diabetes mellitus (T2DM). Sprague-Dawley (SD) rats were randomly divided into the normal control group (NC) and type 2 DM group. DM group received the high-fat and high-sugar diet combined with the intraperitoneal injection of low-dose STZ to establish the type 2 DM rat model. After 12 weeks of feeding, a Morris water maze was used to observe the rats' cognitive ability, and the levels of blood lipid, ucOC, insulin and adiponectin in the two groups were measured. The results showed that blood glucose of rats in DM group was increased significantly at 2–12 weeks (p<0.01) and the body weight was significantly increased at 4–12 weeks (p<0.01). The levels of serum triglyceride (TG), total cholesterol, low-density lipoprotein and insulin in rats in DM group were significantly increased compared with those in NC group (p<0.01) and the levels of high-density lipoprotein, adiponectin and ucOC were significantly decreased compared with those in the NC group (p<0.01). The place navigation and spatial exploration capacities of rats in DM group were significantly decreased compared with those in NC group (p<0.01). In the DM group, the place navigation and spatial exploration capacities of rats in the low ucOC group were significantly decreased compared with those in the high ucOC group (p<0.01). Additionally, single-factor correlation analysis revealed that ucOC was negatively correlated with blood glucose, TG and escape latency (p<0.01), but was positively correlated with adiponectin, residence time in target quadrant and traversing times (p<0.05 or p<0.01). In conclusion, the decreased serum ucOC level in rats with type 2 diabetes mellitus has a certain correlation with cognitive impairment.

Effects of strong noise on cognitive function and some biochemical indexes in serum of guinea pigs

To explore the effect of strong noise on cognitive function and stress hormones, biochemical metabolism enzymes, neuropeptide etc in theserum of guinea pigs, and screen the sensitive bio-markers of noise-induced cognitive impairment. Twenty-four guinea pigs were randomly divided into the noise exposure group and the control group, after the white noise at 120 dB continuously exposed for 4 h. Using Morris water maze to detect the cognitive ability of guinea pigs, and using Elisa kits to detect the content of neuropeptide Y (NPY), neuropeptide P (NPP), neuroglobin (NGB), c-reactive protein (CRP), cortisol (CORT), adrenocorticotropic hormone (ACTH), corticotropin releasing hormone (CRH) and epinephrine (E), norepinephrine (NE), angiotensin Ⅱ (AngⅡ), aldosterone (ALD), oxytocin (OT), vasopressin (VAP), alanine aminotransferase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), and creatine kinase (CK) in the serum of guinea pig. Multiple regression analysis was used to evaluatethe sensitive indexes for the influence of cognitive function. Morris water maze test indicated that the average escape latency of noise exposure group extended obviously, cross platform number and residence time in target quadrant were significantly reduced compared with control group(P<0.01). Elisa results showed that the content of the biochemical indexes above of noise exposure grouphad significant statistical difference except AngⅡ compared with control group(P<0.01), among them, the content of CORT, NPY, NE, NGB, NPP, CK changed obviously and contributed greatly to cognitive in turn. Strong noise at 120dB continuous exposure for 4 h caused a significant decline on cognitive function of guinea pigs, it might be related to the abnormal levels of the physiological and biochemical indexes in serum such as stress hormones, biochemical metabolism enzyme, neuropeptides, neuroglobin etc, and we preliminarily filtrated several sensitive index associated with noise-induced cognitive impairment, including CORT、NPY、NE、NGB、NPP and CK.

Effects of acute hypobaric hypoxia on abilities of learning and memory, the level of nitric oxide and endothelin-1 in hippocampus of mice

Objective To examine the effects of acute hypobaric hypoxia on abilities of learning and memory, the water content in brain, the level of nitric oxide(NO) and endothelin-1(ET-1) in hippocampus of mice. Methods The acute hypobaric hypoxia environment were made by putting the mice in a hypobaric chamber simulated at altitude of 6 000 meters for 8 hours.The capabilities of learning and memory of mice were detected by Morris water maze test.The content of water in hippocampus were examined by measuring the ratio of dry/wet weight, and the level of NO and ET-1 in brain was detected by colorimetric method. Results Morris water maze test showed that the mean escape latency of mice in the hypobaric hypoxia group were longer than that in the normobaric normoxia group((44.60±7.80)s vs (26.39±8.44)s, P<0.01), and the target quadrant residence time were decreased((19.78±2.74)s vs (22.98±6.14)s, P<0.05). Compared with the normobaric normoxia group(NO: (2.37±1.07)μmol/gProt, ET-1: (38.87±6.17)ng/L), the water content in brain of mice in the hypobaric hypoxia group was increased(P<0.05), meanwhile, both the level of NO((4.48±1.45)μmol/gProt) and ET-1((52.09±6.75)ng/L) in brain were increased too(P<0.01). Conclusion Hypobaric hypoxia can decrease the abilities of learning and memory of mice, and these changes might be related with the increased water content and the increased level of NO and ET-1 in hippocampus of mice. Key words: Hypobaric hypoxia; Learning and memory; Nitric oxide; Endothelin-1