Lateral Ventricle Of Rats Research Articles

Nicotinamide Riboside Attenuates Memory Impairment and Depressive-like Behavior in an Alzheimer’s Disease Animal Model

IntroductionDepression in Alzheimer’s disease (AD) differs from major depression in terms of clinical features and treatment. Antidepressants do not provide the expected benefits in depressive symptoms accompanying cognitive decline in AD, suggesting distinct mechanisms. Emerging research suggest that compromised mitophagy, the selective removal of damaged mitochondria, may contribute to the pathogenesis of AD. However boosting nicotinamide adenine dinucleotide (NAD+) to induce mitophagy reduces amyloid β (Aβ) aggregation and enhances cognitive function in AD models (Kerr et al.,Trends Neurosci 2017;40:151-66). Nevertheless, data on NAD’s impact on depression in AD remains limited.ObjectivesThis study aimed to examine the impact of the NAD+ precursor nicotinamide riboside (NR) on cognitive and neuropsychiatric symptoms in a AD rat model.MethodsTo induce the AD, a single dose of 5 μl Aβ1-42 was injected into each lateral ventricle of rats (day 0), while the control group received an intracerebroventricular (icv) saline (0.9%NaCl).Four experimental groups were designed: control (icv saline+po saline), NR (icv saline+po NR), Aβ (icv Aβ+po saline), and Aβ+NR (icv Aβ+po NR).After the injection, to reduce Aβ clearance (Kang et al. Science. 2009;32 1005-7.) rats were subjected to 96 hours of sleep deprivation.Starting from day 6, rats were given either 700 mg/kg oral NR or saline, and handling test scores were recorded daily.The procedures were repeated daily until the rats were sacrificed on day 28.Behavioral experiments were randomly conducted at the end, and statistical analysis was performed using repeated measures ANOVA, followed by the Tukey post hoc test.ResultsPassive avoidance test results showed that the Aβ group had the shortest latency to enter the dark area. However, the Aβ+NR group exhibited a prolonged latency compared to the Aβ group (F(3,2)=5.5;p<0.05). Aβ injection induced depressive-like behavior in rats, as indicated by the forced swim test (FST) for behavioral despair and the sucrose preference test (SPT) for anhedonia. In AD rats treated with NR (Aβ+NR), Aβ-induced depressive-like behavior was reduced, with lower FST immobility scores (F(3,2)=6.2;p<0.05) and increased sucrose preference in the SPT (F(3,2)=7.5;p<0.05). There were no significant differences in anxiety-like behaviors among the groups, assessed by the time spent in the open arm in the elevated plus maze test (F(3,2)=1.9;p>0.05). During the 28-day monitoring period, the Aβ+NR group of rats exhibited a more rapid decrease in aggression levels compared to the other groups in the handling test. This decrease was significant between days 7 and 10 compared to the Aβ group (F(48,5)=1.5;p<0.05).ConclusionsNR improved memory, reduced depressive behavior, and lowered aggression in AD rats. This suggests that NAD+ precursor NR effectively treats cognitive decline and neuropsychiatric symptoms in an AD model.Disclosure of InterestNone Declared

Molecular network mechanism in cerebral ischemia-reperfusion rats treated with human urine stem cells

ObjectiveTo explore the effect of human urine-derived stem cells (husc) in improving the neurological function of rats with cerebral ischemia-reperfusion (CIR), and report new molecular network by bioinformatics, combined with experiment validation. MethodsAfter CIR model was established, and husc were transplanted into the lateral ventricle of rats，neurological severe score (NSS) andgene network analysis were performed. Firstly, we input the keywords “Cerebral reperfusion” and “human urine stem cells” into Genecard database and merged data with findings from PubMed so as to get their targets genes, and downloaded them to make Venny intersection plot. Then, Gene ontology (GO) analysis, kyoto encyclopedia of genes and genomes (KEGG) pathway analysis and protein-protein interaction (PPI) were performed to construct molecular network of core genes. Lastly, the expressional level of core genes was validated via quantitative real-time polymerase chain reaction (qRT-PCR), and localized by immunofluorescence. ResultsCompared with the Sham group, the neurological function of CIR rats was significantly improved after the injection of husc into the lateral ventricle; at 14 days, P = 0.028, which was statistically significant. There were 258 overlapping genes between CIR and husc, and integrated with 252 genes screened from PubMed and CNKI. GO enrichment analysis were mainly involved neutrophil degranulation, neutrophil activation in immune response and platelet positive regulation of degranulation, Hemostasis, blood coagulation, coagulation, etc. KEGG pathway analysis was mainly involved in complement and coagulation cascades, ECM-receptor. Hub genes screened by Cytoscape consist ofCD44, ACTB, FN1, ITGB1, PLG, CASP3, ALB, HSP90AA1, EGF, GAPDH. Lastly, qRT-PCR results showed statistic significance (P < 0.05) in ALB, CD44 and EGF before and after treatment, and EGF immunostaining was localized in neuron of cortex. Conclusionhusc transplantation showed a positive effect in improving neural function of CIR rats, and underlying mechanism is involved in CD44, ALB, and EGF network.

Electroacupuncture Alleviates Cerebral Ischemia-reperfusion Injury by Regulating the S1PR2/TLR4/NLRP3 Signaling Pathway via m6A Methylation of lncRNA H19.

All rats were randomly divided into five groups: the SHAM group, MCAO group, MCAO+EA (MEA) group, MCAO+METTL3 overexpression+EA (METTL3) group and MCAO+lncRNA H19 overexpression+EA (lncRNA H19) group. The middle cerebral artery occlusion (MCAO) rats were established to mimic CIR injury. The overexpression of lncRNA H19 and METTL3 was induced by stereotactic injection of lentiviruses into the rat lateral ventricles. The rats in the MEA, METTL3, and lncRNA H19 groups were treated with EA therapy on "Renzhong" (DU26) and "Baihui" (DU20) acupoints (3.85/6.25Hz; 1mA). Besides, the neurological deficit scoring, cerebral infarction area, pathological changes in brain tissue, total RNA m6A level, and the expression of METTL3, S1PR2, TLR4, NLRP3 and lncRNA H19 were detected in this experiment. EA improved the neurological deficit scoring, cerebral infarction area, and pathological injury in MCAO rats, while these beneficial effects of EA on CIR injury were attenuated by the overexpression of METTL3 or lncRNA H19. More importantly, EA down-regulated the total RNA m6A level and the expression of METTL3, S1PR2, TLR4, NLRP3 and lncRNA H19 in MCAO rats. Instead, the overexpression of METTL3 or lncRNA H19 was found to reverse the EA-induced down-regulation. The findings indicated that EA might down-regulate the S1PR2/TLR4/NLRP3 signaling pathway via m6A methylation of lncRNA H19 to alleviate CIR injury. Our findings provide a new insight into the molecular mechanism of EA on CIR injury.

Capsaicin Changes the Pattern of Brain Rhythms in Sleeping Rats.

The heat and capsaicin sensor TRPV1 ion channels were originally discovered in sensory neurons of dorsal root ganglia, and later found in many other tissues and organs. However, whether TRPV1 channels are present in brain regions other than the hypothalamus has been a subject of debate. Here, we addressed this issue with an unbiased functional test by recording electroencephalograms (EEGs) to examine whether capsaicin injection directly into the rat lateral ventricle could alter brain electrical activity. We observed that EEGs during the sleep stage could be significantly perturbed by capsaicin, whereas EEGs during the awake stage did not show a detectable change. Our results are consistent with TRPV1 expression in selective brain regions whose activities are dominative during the sleep stage.

TAK1 Improves Cognitive Function via Suppressing RIPK1-Driven Neuronal Apoptosis and Necroptosis in Rats with Chronic Hypertension.

Chronic hypertension is a major risk factor for cognitive impairment, which can promote neuroinflammation and neuronal loss in the central nervous system. Transforming growth factor β-activated kinase 1 (TAK1) is a key molecular component in determining cell fate and can be activated by inflammatory cytokines. This study aimed to investigate the role of TAK1 in mediating neuronal survival in the cerebral cortex and hippocampus under chronic hypertensive conditions. To that end, we used stroke-prone renovascular hypertension rats (RHRSP) as chronic hypertension models. Adeno-associated virus (AAV) designed to overexpress or knock down TAK1 expression were injected into the lateral ventricles of rats and the subsequent effects on cognitive function and neuronal survival under chronic hypertensive conditions were assessed. We found that, TAK1 knockdown in RHRSP markedly increased neuronal apoptosis and necroptosis and induced cognitive impairment, which could be reversed by Nec-1s, an inhibitor of receptor interacting protein kinase 1 (RIPK1). In contrast, overexpression of TAK1 in RHRSP significantly suppressed neuronal apoptosis and necroptosis and improved cognitive function. Further knockdown of TAK1 in sham-operated rats received similar phenotype with RHRSP. The results have been verified in vitro. In this study, we provide in vivo and in vitro evidence that TAK1 improves cognitive function by suppressing RIPK1-driven neuronal apoptosis and necroptosis in rats with chronic hypertension.

Transcriptomic Mapping of Neurotoxicity Pathways in the Rat Brain in Response to Intraventricular Polymyxin B.

Intraventricular or intrathecal administration of polymyxins are increasingly used to treat multidrug-resistant (MDR) Gram-negative bacteria caused infections in the central nervous system (CNS). However, our limited knowledge of the mechanisms underpinning polymyxin-induced neurotoxicity significantly hinders the development of safe and efficacious polymyxin dosing regimens. To this end, we conducted transcriptomic analyses of the rat brain and spinal cord 1h following intracerebroventricular administration of polymyxin B into rat lateral ventricle at a clinically relevant dose (0.5mg/kg). Following the treatment, 66 differentially expressed genes (DEGs) were identified in the brain transcriptome while none for the spinal cord (FDR ≤ 0.05, fold-change ≥ 1.5). DEGs were enriched in signaling pathways associated with hormones and neurotransmitters, including dopamine and (nor)epinephrine. Notably, the expression levels of Slc6a3 and Gabra6 were decreased by 20-fold and 4.3-fold, respectively, likely resulting in major perturbations of dopamine and γ-aminobutyric acid signaling in the brain. Mass spectrometry imaging of brain sections revealed a distinct pattern of polymyxin B distribution with the majority accumulating in the injection-side lateral ventricle and subsequently into third and fourth ventricles. Polymyxin B was not detectable in the left lateral ventricle or brain tissue. Electrophysiological measurements on primary cultured rat neurons revealed a large inward current and significant membrane leakage following polymyxin B treatment. Our work demonstrates, for the first time, the key CNS signaling pathways associated with polymyxin neurotoxicity. This mechanistic insight combined with pharmacokinetic/pharmacodynamic dosing strategies will help guide the design of safe and effective intraventricular/intrathecal polymyxin treatment regimens for CNS infections caused by MDR Gram-negative pathogens.

Intraventricular Drug Delivery and Sampling for Pharmacokinetics and Pharmacodynamics Study.

Although the blood-brain barrier (BBB) protects the brain from foreign entities, it also prevents some therapeutics from crossing into the central nervous system (CNS) to ameliorate diseases or infections. Drugs are administered directly into the CNS in animals and humans to circumvent the BBB. The present protocol describes a unique way of treating brain infections through intraventricular delivery of antibiotics, i.e., polymyxins, the last-line antibiotics to treat multi-drug resistant Gram-negative bacteria. A straightforward stereotaxic surgery protocol was developed to implant a guide cannula reaching into the lateral ventricle in rats. After a recovery period of 24 h, rats can be injected consciously and repeatedly through a cannula that is fitted to the guide. Injections can be delivered manually as a bolus or infusion using a microinjection pump to obtain a slow and controlled flow rate. The intraventricular injection was successfully confirmed with Evans Blue dye. Cerebrospinal fluid (CSF) can be drained, and the brain and other organs can be collected. This approach is highly amenable for studies involving drug delivery to the CNS and subsequent assessment of pharmacokinetic and pharmacodynamic activity.

Inhibiting microRNA-142–5p improves learning and memory in Alzheimer’s disease rats via targeted regulation of the PTPN1-mediated Akt pathway

ObjectiveMicroRNAs (miRNAs) have been recognized as possible biomarkers for Alzheimer’s disease (AD). MiR-142–5p has been reported to be abnormally expressed in brain tissues. However, the role of miR-142–5p in AD pathogenesis keeps unclear. This study aimed to investigate the effect of miR-142–5p on the learning and memory of AD rats via regulation of protein tyrosine phosphatase nonreceptor type 1 (PTPN1)-mediated protein kinase B (Akt) pathway. MethodsThe AD model was established by injection of Aβ1–42 oligomer once into the lateral ventricle of rats, and the spatial learning and memory ability of rats was measured. AD rats were injected with miR-142–5p or PTPN1 vectors to explore their functions in inflammation, Aβ, p-tau protein, apoptosis in brain tissues, and the effects on Akt pathway. The targeting relationship between miR-142–5p and PTPN1 was detected. ResultsOverexpressed miR-142–5p, down-regulated PTPN1 and inactivated Akt pathway were exhibited in AD. MiR-142–5p targeted PTPN1 to mediate Akt pathway. Reduced miR-142–5p and elevated PTPN1 improved the behavior of AD rats. MiR-142–5p targeted PTPN1 to effectively inhibit Aβ formation and abnormal phosphorylation of p-tau protein, suppress the inflammation in the brain tissues of AD rat, and improve the survival rate of brain tissue cells. MiR-142–5p regulated PTPN1 to activate the Akt pathway, further inhibiting the apoptosis of brain neurons in AD rats. ConclusionDown-regulating miR-142–5p targets PTPN1 to activate Akt pathway, thus improving the learning and memory of AD rats and playing an anti-AD role.

Expression of D5 dopamine receptors in the lateral ventricle walls during post-weaning rat development.

Even before the first synapses appear, neurotransmitters and their receptors are present in the developing brain, regulating the cell fate of neuronal progenitors in neurogenic niches, such as the lateral ventricle. In particular, dopamine appears to play a pivotal role in the neurogenesis of the subventricular zone by controlling the proliferation and differentiation of progenitors through activation of different receptors. Although dopamine receptor 5 (D5R) is expressed prenatally, there is little information regarding its role in either pre- or postnatal forebrain development. To examine the role of D5Rs in neurogenesis in the rat lateral ventricle subventricular zone (V-SVZ), we immunohistochemically defined D5R expression, as well as BrdU incorporation in progenitor cells of various post-weaning stages (Post-natal day (P) 20 until P80). We found that the level of proliferating cells is stable from postnatal day 20 until 50, and then declines sharply on P80. Concomitantly, D5R is expressed in all ages examined, but we detected a progressive decrease in the density of D5R+ cells from P40 until P80. Moreover, double immunostaining for BrdU and D5R revealed that proliferating cells in V-SVZ also express D5R. Collectively, our data suggest that D5R is expressed in the post-weaning V-SVZ of rat at least until P80, and its expression pattern coincides with that of proliferating cells in the V-SVZ, hinting at a possible role of D5Rs in the regulation of neuronal progenitor division/differentiation.

Tongmai granules improve rat hippocampal injury by regulating TLR4/MyD88/AP-1 signaling pathway

Ethnopharmacological relevanceTongmai granules (TMG) is composed of Salvia miltiorrhiza Bge., Radix puerariae Lobata., and Ligusticum chuanxiong hort. TMG is mainly used for ischemic cardiovascular, cerebrovascular diseases, atherosclerosis, coronary heart disease, cerebral infarction and cerebral ischemia. TMG is a kind of traditional compound granule, which has a protective effect on brain injury. However, the potential protective mechanism of the TMG has not been elucidated. Aim of the studyTMG has a good effect on brain injury, but its brain protective mechanism is still unclear. The purpose of this study was to confirm the neuroprotective mechanism of TMG, reveal its target genes and identify the active components of TMG. Materials and methodsHigh-performance liquid chromatography (HPLC) was used to identify the fingerprint of TMG. UPLC-Q-TOF-MSE was used to analyze the base peak intensity (BPI) chromatograms of TMG. TMG was pre-administered for one week, brain injury and edema were induced by injection of glutamate (Glu) into the lateral ventricles of rats. HE staining was used to investigate the pathological damage caused by Glu in the hippocampus of rats, and the RNA-seq was used to analyze the changes of different genes before and after TMG treatment. Finally, changes of related proteins were analyzed by qRT-PCR, Western blot, and other molecular biological methods. Dosage of TMG were set to 0.6 g/kg, 1.2 g/kg and 2.4 g/kg. ResultsWe found that TMG contained many active components, including salvianolic acid, puerarin, ferulic acid, etc. TMG could improve cerebral edema and brain injury induced by Glu. After TMG treatment, differential gene analysis showed that differential genes were significantly enriched in toll-like receptor signaling pathway. qRT-PCR validation results were consistent with RNA-Seq analysis results. Combined with Western blot analysis, we found that TMG ultimately regulated the expression of inflammatory cytokines by affecting the TLR4/MyD88/AP-1 pathway. ConclusionsIn this study, we combined TMG with RNA-seq analysis to demonstrate that TMG may play a neuroprotective role by regulating Toll-like receptor signaling pathway and down-regulating the expression of inflammatory cytokine. TMG may become a kind of traditional Chinese medicine with neuroprotective potential.

Protective mechanism of FoxO1 against early brain injury after subarachnoid hemorrhage by regulating autophagy.

IntroductionEarly brain injury (EBI) plays a key role in the devastating outcomes after subarachnoid hemorrhage (SAH). Autophagy and apoptosis may share a common molecular inducer that regulates the process of cell death. FoxO1, as a key regulator of neuronal autophagy which is involved in apoptosis, has not been reported in SAH rats. This work was to investigate the protective and anti‐inflammatory effects of FoxO1 on EBI after SAH by regulating autophagy.MethodsIn this study, we constructed the SAH model. In experiment I, low dose (50 μl of 1 × 108 IU/ml) or high dose (50 μl of 1 × 1010 IU/ml) of FoxO1 gene overexpressed adenovirus vector was injected into the lateral ventricle of rats before SAH. In experiment II, we reported the effect of FoxO1 overexpress on nerve function recovery, oedema, BBB leakage, neuronal death in rats after SAH through autophagy regulation. Post‐SAH evaluation included neurological function score, brain water content, evans blue exosmosis, pathological changes, inflammatory response and apoptosis.ResultsThe experiment I showed that either low or high dose of ad‐FoxO1 could significantly improve nerve function, reduce cerebral water content and reduce blood‐brain barrier (BBB) destruction in rats, indicating that ad‐FoxO1 had a protective effect on brain injury in rats EBI after SAH. In addition, ad‐FoxO1 promoted autophagy in rat hippocampal tissue, as evidenced by accumulation of LC3II/I and Beclin‐1 and degradation of p62. Furthermore, ad‐FoxO1 inhibited the inflammatory response and apoptosis of rat hippocampal neurons after SAH. The experiment II showed that both ad‐FoxO1 and rapamycin attenuated the injury of nerve function in rats after SAH, and this synergistic effect further reduced cerebral edema and evansblue extravasation, decreased hippocampus neuronal cell apoptosis, and declined inflammatory response. However, this was contrary to the results of chloroquine. These findings suggested that FoxO1 regulated the neural function of EBI after SAH through the autophagy pathway.ConclusionsThe findings in this study was beneficial for identifying the novel therapeutic target for the treatment of SAH.

Inhibition of serum and glucocorticoid regulated kinases by GSK650394 reduced infarct size in early cerebral ischemia-reperfusion with decreased BBB disruption

Blood-brain barrier (BBB) disruption is one of the most important pathological changes following cerebral ischemia-reperfusion. We tested whether inhibition of the serum and glucocorticoid regulated kinase 1 (SGK1) would decrease BBB disruption and contribute to decreasing infarct size in the first few hours of cerebral ischemia-reperfusion within the thrombolysis therapy time window. After transient middle cerebral artery occlusion (MCAO), an SGK1 inhibitor GSK650394, or vehicle was administered into the lateral ventricle of rats. After one hour of MCAO and two hours of reperfusion, we determined BBB disruption using the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid, and also determined infarct size, phosphorylation of NDRG1, and MMP2 protein level. Ischemia-reperfusion increased (+34%, p < 0.05) and GSK650394 decreased (−25%, p < 0.05) the Ki in the ischemic-reperfused cortex. GSK650394 decreased the percentage of cortical infarct (−31%, p < 0.001). At the same time GSK650394 reduced NDRG1 phosphorylation and MMP2 protein level in the ischemic-reperfused cortex suggesting that SGK1 was inhibited by GSK650394 and that lower MMP2 could be one of the mechanisms of decreased BBB disruption. Collectively our data suggest that GSK650394 could be neuroprotective and one of the mechanisms of the neuroprotection could be decreased BBB disruption. SGK1 inhibition within the thrombolysis therapy time window might reduce cerebral ischemia-reperfusion injury.

MRI tracking/detection of bone marrow mesenchymal stromal cells transplantation for treatment of ischemic cerebral infarction.

Cerebral stroke is the second leading cause of death with high mortality and morbidity worldwide, currently it lacks effective therapies to improve the prognosis. This study was aimed to explore the role of bone marrow mesenchymal stem cells (BMSCs) transplantation in the recovery of brain structure and function after ischemic cerebral infarction by magnetic resonance imaging (MRI). By applying internal carotid artery embolization, the ischemic cerebral infarction model in rats was established. MRI was performed to detect the imaging changes in the brain tissue after modeling, and the successful modeling was evidenced by the presence of obvious high-signal infarct areas in the brain. BMSCs were then injected into the lateral ventricles of rats, and the recovery of brain tissue and function were quantitatively evaluated by T2-weighted image (T2WI) and voxel-based morphology (VBM) after 28days. The results showed that BMSCs were cell subsets with multiple differentiation potentials. Deficits caused by Ischemic cerebral infarction were relieved by BMSCs transplantation, including increase in damaged cerebral tissue and recovery of cerebral function. In addition, the combined imaging technology of VBM and T2WI quantitatively revealed the effectiveness of BMSCs in repairing damaged brain tissue structure and function. Taken together, the results revealed that the transplantation of BMSCs into the lateral ventricle was beneficial to repair the structure and function of the damaged brain tissue after ischemic cerebral infarction. Moreover, the combination of VBM and T2WI technology can detect the level of brain injury in ischemic cerebral infarction dynamically and noninvasively, and evaluate the recovery of structure and function of damaged brain tissue.

Ruthenium red, mitochondrial calcium uniporter inhibitor, attenuates cognitive deficits in STZ-ICV challenged experimental animals

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with cardinal features of cognitive dysfunction in an individual. Recently, the blockade of mitochondrial calcium uniporter (MCU) exhibits neuroprotective activity in experimental animals. However, the therapeutic potential of MCU has not yet been established in the management of AD. Therefore, the present study explored the therapeutic potential of either Ruthenium red (RR), a MCU blocker, or Spermine, a MCU opener, on the extent of mitochondrial calcium accumulation, function, integrity and bioenergetics in hippocampus, pre-frontal cortex and amygdale of ICV-STZ challenged rats. Experimental AD was induced in male rats by intracerebroventricular injection of streptozotocin (ICV-STZ) on day-1 (D-1) of the experimental protocol at a sub-diabetogenic dose (3 mg/kg) twice at an interval of 48 h into both rat lateral ventricles. RR attenuated ICV-STZ-induced memory-related behavioral abnormalities in Morris water maze and Y-maze tests. RR also attenuated ICV-STZ-induced decrease in the level of acetylcholine and activity of choline acetyltransferase and, increase in the activity of acetylcholinestarase in memory-sensitive rat brain regions. Further, RR attenuated mitochondrial toxicity in terms of reducing mitochondrial calcium accumulation and improving the mitochondrial function, integrity and bioenergetics in memory-sensitive brain regions of ICV-STZ challenged rats. Furthermore, RR attenuated the percentage of apoptotic cells in ICV-STZ challenged rat brain regions. However, Spermine did not alter ICV-STZ-induced behavioral, biochemical and molecular observations in any of the brain regions. These observations indicate the fact that the MCU blockage could be a potential therapeutic option in the management of sporadic type of AD.

Intracerebroventricular streptozotocin administration impairs mitochondrial calcium homeostasis and bioenergetics in memory-sensitive rat brain regions.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with cardinal manifestation of cognitive dysfunction. The limitation to avail a successful drug candidate encourages researchers to establish an appropriate animal model in the novel anti-AD drug discovery process. In this context, the mechanism of mitochondrial dysfunction in cognitive deficit animals is yet to be established for intracerebroventricular injection of streptozotocin (ICV-STZ). Experimental dementia was induced in male rats by ICV-STZ on day-1 (D-1) of the experimental protocol at a sub-diabetogenic dose (3mg/kg) twice at an interval of 48h into both rat lateral ventricles. ICV-STZ caused cognitive decline in terms of increase in the escape latency on D-14 to D-17 and, decrease in the time spent and percentage of distance travelled in the target quadrant during Morris water maze and decrease in the spontaneous alteration behavior during Y-maze tests in rats. Further, ICV-STZ decreased the level of acetylcholine and activity of choline acetyltransferase and increased the activity of acetylcholinesterase in rat hippocampus, pre-frontal cortex and amygdala. Interestingly, ICV-STZ increased the mitochondrial calcium in addition to decrease in the mitochondrial function, integrity and bioenergetics in all rat brain regions. Further, ICV-STZ enhanced the levels of expression of NR1 subunit of N-methyl-D-aspartate receptor, mitochondrial calcium uniporter and sodium-calcium exchanger in these rat brain regions. Thus, NR1-dependent mitochondrial calcium accumulation could be considered as a major attribute to the animal model of ICV-STZ-induced AD-like manifestations. Further, drugs targeting to manage mitochondrial calcium homeostasis could best be studied in this animal model.

Capsaicin changes the pattern of brain rhythms in sleeping rat

The heat and capsaicin sensor TRPV1 ion channels were originally discovered from sensory neurons in dorsal root ganglia, and later found in many other tissues and organs. However, whether TRPV1 channels are present in brain regions other than hypothalamus has been a subject of debate. Here we addressed this issue with an unbiased functional test, by recording electroencephalogram (EEG) to examine whether capsaicin injection directly into the rat lateral ventricle could alter brain electrical activity. We observed that EEG during the sleep stage could be significantly perturbed by capsaicin, whereas EEG during the awake stage did not show a detectable change. Our results are consistent with TRPV1 expression in selective brain regions whose activities are dominative during the sleep stage.Support or Funding InformationThis work is supported by funding from the Qingdao Postdoctoral Research Project to YHT.

Protective effect of hypoxia inducible factor-1α gene therapy using recombinant adenovirus in cerebral ischaemia-reperfusion injuries in rats

Context Hypoxia-inducible factor-1α (HIF-1α)-induced genes can improve blood circulation. Objective To investigate brain protective effect of recombinant adenovirus-mediated HIF-1α (AdHIF-1α) expression and its mechanism. Materials and methods Male SD rats were used to establish focal cerebral ischaemia-reperfusion (CIR) injury models and randomly divided into normal, sham, CIR, Ad and AdHIF-1α groups. Ad or AdHIF-1α (108 pfu/10 µL) were administered into lateral ventricle of rats in Ad and AdHIF-1α groups. Modified neurological severity score (mNSS), brain water content (BWC) and cerebral infarct volumes (CIVs) were analyzed, and HE staining was performed using the brain tissues. Furthermore, the expression of caspase-3 and HSP90 was analyzed using qRT-PCR and Western blotting. Results Compared to CIR (mNSS, 8.52 ± 0.52; CIV, 0.22 ± 0.01) and Ad groups (mNSS, 8.83 ± 0.41; CIV, 0.22 ± 0.02), mNSS and CIV were significantly decreased in AdHIF-1α group (mNSS, 6.03 ± 0.61; CIV, 0.11 ± 0.01) at 72 h (p < 0.05). With prolonged reperfusion time (6 h to 72 h), BWC of all rats increased gradually, although the increase was markedly less in AdHIF-1α group (78.15 ± 0.16 to 87.01 ± 0.31) compared to that in CIR (78.77 ± 0.60 to 89.74 ± 0.34) and Ad groups (78.77 ± 0.35 to 89.71 ± 0.27) (p < 0.01). There were significantly greater pathological changes in the neurons in AdHIF-1α group at 72 h following CIR. Furthermore, expression of caspase-3 (p < 0.01) down-regulated and HSP90 up-regulated (p < 0.05) at mRNA and protein levels in AdHIF-1α group. Discussion and conclusions HIF‑1α gene therapy is neuroprotective towards the CIR rat model. HIF-1α may be a candidate gene for the treatment of ischaemic brain injury.

The pH-Sensitive Potassium Channel TASK-1 Is a Chemosensor for Central Respiratory Regulation in Rats

TWIK-related acid-sensitive potassium channel-1 (TASK-1) is a "leak" potassium channel sensitive to extracellular protons. It contributes to setting the resting potential in mammalian neurons. TASK-1 channels are widely expressed in respiratory-related neurons in the central nervous system. Inhibition of TASK-1 by extracellular acidosis can depolarize and increase the excitability of these cells. Here we describe the distribution of TASK-1 in the rat brainstem and show that TASK-1 mRNAs are present in respiratory-related nuclei in the ventrolateral medulla, which have been proposed as neural substrates for central chemo-reception in rats. After inhalation of 8% CO2 for 30 and 60 min, TASK-1 mRNA levels in positive-expression neurons were remarkably upregulated. Injection of the TASK-1 blocker anandamide (AEA) into the rat lateral cerebral ventricle, showed a significant excitement of respiratory at 10 min posttreatment, with a marked decrease in inspiratory and expiratory durations and an increased frequency of respiration. We suggest that TASK-1 channel may serve as a chemosensor for in central respiration and may contribute to pH-sensitive respiratory effects. TASK-1 channel might be an attractive candidate for sensing H^(+)/CO2 in several respiratory-related nuclei in the brainstem. It is likely that TASK-1 participates in pH-sensitive chemical regulation in the respiratory center under physiological and pathological conditions.

Histamine Induces Microglia Activation and the Release of Proinflammatory Mediators in Rat Brain Via H1R or H4R.

Histamine is a major peripheral inflammatory mediator and a neurotransmitter in the central nervous system. We have reported that histamine induces microglia activation and releases proinflammatory factors in primary cultured microglia. Whether histamine has similar effects in vivo is unknown. In the present study, we aimed to investigate the role of histamine and its receptors in the release of inflammatory mediators and activation of microglia in rat brain. We site-directed injected histamine, histamine receptor agonists or histamine receptor antagonists in the rat lateral ventricle using stereotaxic techniques. Flow cytometry was employed to determine histamine receptor expression in rat microglia. Microglia activation was assessed by Iba1 immunohistochemistry. The levels of tumour necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and interleukin-10 (IL-10) were measured with commercial enzyme-linked immunosorbent assay (ELISA) kits, TNF-α, IL-1β and IL-10 mRNA expressions were determined with Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). We found that all four types of histamine receptors were expressed in rat brain microglia. Histamine was able to induce microglia activation and subsequent production of the inflammatory factors TNF-α, IL-1β and IL-10, and these effects were partially abolished by H1R and H4R antagonists. However, H2R and H3R antagonists significantly increased production of TNF-α and IL-1β, and decreased IL-10 levels. The H1R or H4R agonists stimulated the production of TNF-α and IL-1β, while the H2R or H3R agonists increased IL-10 release. Our results demonstrate that histamine induces microglia activation and the release of both proinflammatory and anti-inflammatory factors in rat brain, thus contributing to the development of inflammation in the brain. Graphical Abstract Histamine induces microglia activation and the release of both proinflammatory (TNF-α and IL-1β) and anti-inflammatory factors (IL-10) in rat brain, thus contributing to the development of inflammation in the brain.

Effect of lncRNA GAS5 on the apoptosis of neurons via the notch1 signaling pathway in rats with cerebral infarction.

To observe the effect of long non-coding ribonucleic acid (lncRNA) growth arrest specific 5 (GAS5) knockdown on the apoptosis of neurons in rats with cerebral infarction (CI), and to explore the potential mechanism of lncRNA GAS5 in the pathogenesis of CI. A total of 60 adult male Sprague Dawley (SD) rats aged 12-14 weeks old and weighing (267.14±6.49) g were randomly divided into three groups: Sham operation group (Sham group, n=20), CI group (n=20) and CI + lncRNA GAS5 knockdown group [CI + GAS5 small interfering RNA (siRNA) group, n=20]. The rat model of focal CI was constructed by carotid artery embolization. After the CI model was successfully induced, a certain amount of lncRNA GAS5 siRNAs was injected into the rat lateral ventricle in a stereotactic manner. At 24 h after operation, triphenyl tetrazolium chloride (TTC) method was used to detect the infarction area in brain tissues of rats in each group. At the same time, the pathological changes of neurons in the hippocampus and prefrontal cortex of rats in each group were observed via hematoxylin and eosin (H&E) staining. The expressions of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX) were detected via Western blotting. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was adopted to detect the number of apoptotic neurons in brain tissues of rats in each group. Meanwhile, the expression level of Notch intracellular domain (NICD) proteins was measured using the Western blotting technique and immunohistochemical staining. Reverse transcription-polymerase chain reaction (RT-PCR) showed that the lncRNA GAS5 expression in brain tissues of rats in CI group was significantly higher than that of rats in Sham group (p<0.05). TTC staining results revealed that lncRNA GAS5 knockdown could remarkably reduce the CI area of rats in CI group (p<0.05). In addition, inhibiting lncRNA GAS5 could also significantly reduce the level of pro-apoptotic gene BAX and increase the expression level of anti-apoptotic gene Bcl-2 (p<0.05). In the meantime, the number of apoptotic neurons in CI + GAS5 siRNA group was also evidently decreased (p<0.05). Finally, it was found that lncRNA GAS5 knockdown notably inhibited the expression of NICD proteins (p<0.05). The inhibitory effect of lncRNA GAS5 knockdown on the apoptosis of neurons in CI rats may be related to the activation of the Notch1 signaling pathway. LncRNA GAS5 may be a new target for clinical treatment of CI.