Number Of Iba1-positive Cells Research Articles

Polarization to M1-type microglia in the hippocampus is involved in depression-like behavior in a mouse model of olfactory dysfunction

Impaired olfactory function may be associated with the development of psychiatric disorders such as depression and anxiety; however, knowledge on the mechanisms underlying psychiatric disorders is incomplete. A reversible model of olfactory dysfunction, zinc sulfate (ZnSO4) nasal-treated mice, exhibit depression-like behavior accompanying olfactory dysfunction. Therefore, we investigated olfactory function and depression-like behaviors in ZnSO4-treated mice using the buried food finding test and tail suspension test, respectively; investigated the changes in the hippocampal microglial activity and neurogenesis in the dentate gyrus by immunohistochemistry; and evaluated the inflammation and microglial polarity related-proteins in the hippocampus using western blot study. On day 14 after treatment, ZnSO4-treated mice showed depression-like behavior in the tail suspension test and recovery of the olfactory function in the buried food finding test. In the hippocampus of ZnSO4-treated mice, expression levels of ionized calcium-binding adapter molecule 1 (Iba1), cluster of differentiation 40, inducible nitric oxide synthase, interleukin (IL)-1β, IL-6, tumor necrosis factor-α, cleaved caspase-3, as well as the number of Iba1-positive cells and cell body size increased, and arginase-1 expression and neurogenesis decreased. Except for the increased IL-6, these changes were prevented by a microglia activation inhibitor, minocycline. The findings suggest that neuroinflammation due to polarization of M1-type hippocampal microglia is involved in depression accompanied with olfactory dysfunction.

Hippocampal and gut AMPK activation attenuates enterocolitis-like symptoms and co-occurring depressive-like behavior in ulcerative colitis model mice: Involvement of brain-gut autophagy

Patients with inflammatory bowel disease, including ulcerative colitis (UC) and Crohn's disease, have a high incidence of psychiatric disorders, including depression and anxiety. However, the underlying pathogenic mechanism remains unknown. Dextran sulfate sodium (DSS)-treated mice, a model of UC, exhibit depressive-like behavior and reduced adenosine monophosphate-activated protein kinase (AMPK) activity, which regulates various physiological functions in the brain and gut. However, comprehensive studies on UC pathophysiology with co-occurring depression focused on brain-gut AMPK activity are lacking. Therefore, we aimed to investigate whether resveratrol (RES), an AMPK activator, prevented DSS-induced UC-like symptoms and depressive-like behavior. DSS treatment induced UC-like pathology and depressive-like behavior, as assessed via the tail suspension test. Moreover, western blotting and immunohistochemical studies revealed that DSS increased p-p70S6 kinase (Thr389), p62, tumor necrosis factor-α, interleukin (IL)-1β, IL-18, NLR family pyrin domain containing 3 (NLRP3), cleaved caspase-1, cleaved Gasdermin-D (GSDMD), and cleaved caspase-3 expression levels in the rectum and hippocampus, and increased CD40, iNOS, and Kelch-like ECH-associated protein 1 expression levels, and the number of Iba1-positive cells in the hippocampus, and decreased p-AMPK and LC3II/I expression levels, and the number of NF-E2-related factor 2 (Nrf2)-positive cells, and reduced neurogenesis in the hippocampus. These changes were reversed by the RES administration. RES also enhanced PGC1α and SOD1 expression in the hippocampus of DSS-treated male mice. Moreover, NLRP3 staining was observed in the neurons and microglia, and cleaved GSDMD staining in neurons in the hippocampus of DSS-treated mice. Notably, RES prevented UC-like pathology and depressive-like behavior and enhancement of autophagy, decreased rectal and hippocampal inflammatory cytokines and inflammasome, and induced the Nrf2-PGC1α-SOD1 pathway in the hippocampus, resulting in neurogenesis in the hippocampal dentate gyrus. Our findings suggest that brain-gut AMPK activation may be an important therapeutic strategy in patients with UC and depression.

Protective effects of the salt-induced kinase inhibitor HG-9-91-01 on sepsis-associated cognitive dysfunction in mice and the underlying mechanisms.

Sepsis-associated cognitive dysfunction is a common complication in patients with sepsis and lack of effective treatment. Its pathological mechanisms remain unclear. Salt-induced kinase (SIK) is an important molecule in the regulation of metabolism, immunity, and inflammatory response. It is associated with the development of many neurological diseases. This study aims to investigate the expression of SIK in the hippocampus of septic mice, and to evaluate the role and mechanism of the SIK inhibitor HG-9-91-01 in sepsis-associated cognitive dysfunction. Firstly, C57BL/6 mice were randomly divided into a control group (Con group) and a sepsis model group [lipopolysaccharide (LPS) group]. The model group was injected intraperitoneally with LPS at a dose of 8 mg/kg and the Con group was injected with an equal volume of normal saline. Hippocampal tissues were harvested at 1, 3, and 6 days after injection and the expressions of SIK1, SIK2, and SIK3 were detected by real-time fluorescence quantitative PCR (qPCR) and Western blotting. Secondly, C57BL/6 mice were randomly divided into a Con group, a LPS group, and a SIK inhibitor group (HG group). The LPS and HG groups were injected with LPS to establish a sepsis model; in the HG group, HG-9-91-01 (10 mg/kg) was injected intraperitoneally at 3-6 days after LPS injection, and the LPS group was injected with the same volume of vehicle. Cognitive function was assessed at 7-11 days after LPS injection using the Morris water maze (MWM). Hippocampal tissues were harvested after the behavioral tests, and the mRNA levels of inflammatory factors and microglial markers were assessed by qPCR. The protein levels of inducible nitric oxide synthase (iNOS), CD68, ionized calcium binding adaptor molecule 1 (Iba-1), N-methyl-D-aspartate (NMDA) receptor (NR) subunit, cAMP response element-binding protein (CREB)-regulated transcription coactivator 1 (CRTC1), and insulin-like growth factor 1 (IGF-1) were detected by Western blotting. Immunohistochemistry (IHC) was used to detect the expression of Iba-1 positive cells in the CA1, CA3 and dentate gyrus (DG) of the hippocampus, followed by Sholl analysis. Compared with the Con group, the mRNA and protein levels of SIK1, SIK2, and SIK3 in the hippocampus were increased in the LPS group (all P<0.05). Compared with the Con group, mice in the LPS group had a significantly longer escape latency, a lower percentage of target quadrant dwell time and a reduced locomotor speed (all P<0.05); the HG group had a decreased escape latency and an increased percentage of time spent in the target quadrant in comparison with the LPS group (both P<0.05). The mRNA levels of inflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6)], and the M1-type microglial markers iNOS and CD68 in the hippocampus of the LPS group were increased in comparison with the Con group, while the M2-type microglial markers CD206 and arginase-1 (Arg-1) were decreased. Compared with the LPS group, the mRNA levels of TNF-α, IL-1β, IL-6, and iNOS were downregulated, while the levels of CD206 and Arg-1 were upregulated in the HG group (all P<0.05). The protein levels of iNOS, CD68, and Iba-1 in the hippocampus of the LPS group were increased in comparison with the Con group, but they were downregulated in the HG group in comparison with the LPS group (all P<0.05). The number of Iba-1 positive cells in CA1, CA3, and DG of the hippocampus was increased in the LPS group in comparison with the Con group, but they were decreased in the HG group in comparison with the LPS group (all P<0.05). Sholl analysis showed that the number of intersections at all radii between 8-38 µm from the microglial soma was decreased in the LPS group in comparison with the Con group (all P<0.05). Compared with the LPS group, the number of intersections at all radii between 14-20 µm was significantly increased in the HG group (all P<0.05). The protein levels of NR subunit NR1, NR2A, NR2B, and IGF-1 were downregulated in the hippocampus of the LPS group in comparison with the Con group, while the expression of phosphorylated CRTC1 (p-CRTC1) was increased. Compared with the LPS group, the levels of NR1, NR2A, NR2B, and IGF-1 were upregulated, while p-CRTC1 was downregulated in the HG group (all P<0.05). SIK expression is upregulated in the hippocampus of septic mice. The SIK inhibitor HG-9-91-01 ameliorates sepsis-associated cognitive dysfunction in mice, and the mechanism may involve in the activation of the CRTC1/IGF-1 pathway, inhibition of neuroinflammation, and enhancement of synaptic plasticity.

Maternal infection during pregnancy aggravates the behavioral response to an immune challenge during adolescence in female rats

Prenatal and early postnatal infection have been associated with changes in microglial activity and the development of psychiatric disorders. Here, we investigated the effect of prenatal immune activation and postnatal immune challenge, alone and combined, on behavior and microglial cell density in female Wistar rats. Pregnant rats were injected with poly I:C to induce a maternal immune activation (MIA). Their female offspring were subsequently exposed to a lipopolysaccharide (LPS) immune challenge during adolescence. Anhedonia, social behavior, anxiety, locomotion, and working memory were measured with the sucrose preference, social interaction, open field, elevated-plus maze, and Y-maze test, respectively. Microglia cell density was quantified by counting the number of Iba-1 positive cells in the brain cortex. Female MIA offspring were more susceptible to the LPS immune challenge during adolescence than control offspring as demonstrated by a more pronounced reduction in sucrose preference and body weight on the days following the LPS immune challenge. Furthermore, only the rats exposed to both MIA and LPS showed long-lasting changes in social behavior and locomotion. Conversely, the combination MIA and LPS prevented the anxiety induced by MIA alone during adulthood. MIA, LPS, or their combination did not change microglial cell density in the parietal and frontal cortex of adult rats. The results of our study suggest that the maternal immune activation during pregnancy aggravates the response to an immune challenge during adolescence in female rats.

Identification of Key Genes and Pathways in the Hippocampus after Traumatic Brain Injury: Bioinformatics Analysis and Experimental Validation

Traumatic brain injury (TBI) is a common brain injury with a high morbidity and mortality. The complex injury cascade triggered by TBI can result in permanent neurological dysfunction such as cognitive impairment. In order to provide new insights for elucidating the underlying molecular mechanisms of TBI, this study systematically analyzed the transcriptome data of the rat hippocampus in the subacute phase of TBI. Two datasets (GSE111452 and GSE173975) were downloaded from the Gene Expression Omnibus (GEO) database. Systematic bioinformatics analyses were performed, including differentially expressed genes (DEGs) analysis, gene set enrichment analysis (GSEA), Gene Ontology (GO) enrichment analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, protein-protein interaction (PPI) network construction, and hub gene identification. In addition, hematoxylin and eosin (HE), Nissl, and immunohistochemical staining were performed to assess the injured hippocampus in a TBI rat model. The hub genes identified by bioinformatics analyses were verified at the mRNA expression level. A total of 56 DEGs were shared in the two datasets. GSEA results suggested significant enrichment in the MAPK and PI3K/Akt pathways, focal adhesion, and cellular senescence. GO and KEGG analyses showed that the common DEGs were predominantly related to immune and inflammatory processes, including antigen processing and presentation, leukocyte-mediated immunity, adaptive immune response, lymphocyte-mediated immunity, phagosome, lysosome, and complement and coagulation cascades. A PPI network of the common DEGs was constructed, and 15 hub genes were identified. In the shared DEGs, we identified two transcription co-factors and 15 immune-related genes. The results of GO analysis indicated that these immune-related DEGs were mainly enriched in biological processes associated with the activation of multiple cells such as microglia, astrocytes, and macrophages. HE and Nissl staining results demonstrated overt hippocampal neuronal damage. Immunohistochemical staining revealed a marked increase in the number of Iba1-positive cells in the injured hippocampus. The mRNA expression levels of the hub genes were consistent with the transcriptome data. This study highlighted the potential pathological processes in TBI-related hippocampal impairment. The crucial genes identified in this study may serve as novel biomarkers and therapeutic targets, accelerating the pace of developing effective treatments for TBI-related hippocampal impairment.

Effects of different doses of lithium on the central nervous system in the rat valproic acid model of autism

Epidemiological studies have shown that low doses of lithium in the environment can have beneficial effects on mental health. Autism spectrum disorder, a neurodevelopmental disorder in which patients exhibit abnormal behaviors, pharmacological interventions usually relied on a range of psychotropic medications. However, such medications often produce severe side effects or are ineffective in symptoms. Finding alternative ways to improve abnormal behaviors in individuals with autism are warranted, in which case lithium may be a relatively safe and effective medication. Lithium salt therapy is used to treat a variety of neuropsychiatric disorders and has neuroprotective effects. In this study, we investigated the effects of different doses of lithium on neurobehavioural disorders using the rat model of autism established by valproic acid (VPA) injection. Lithium was observed to have an ameliorative effect on the social cognitive, social memory and anxiety levels in the rat model of autism. Immunofluorescence staining showed that subchronic LiCl administration (1.0 mmol/kg) significantly reduced the number of Iba-1 positive cells in the CA1 region of the hippocampus in VPA group and brought it close to the levels of control group. Significantly lower levels of the pro-inflammatory marker IL-6 were observed in the hippocampus and serum after lithium treatment. In addition, the lithium treatment increased the levels of H3K9 acetylation in the hippocampus of VPA-exposed rats. The results showed a defensive effect of environment-related lithium exposure doses on neurobehavioural deficits in the rat valproic acid model of autism, suggesting that it may be a potential drug for the treatment of autism.

Electroacupuncture relieves hyperalgesia by regulating neuronal-glial interaction and glutamate transporters of spinal dorsal horns in rats with acute incisional neck pain.

Glial cells are involved in the analgesic effect of electroacupuncture (EA) in rats with chronic neurological pain. The objective of this study was to observe the role of neuronal-glial interaction and glutamate (Glu) transporters in EA-induced acute neck pain relief in rats. Male rats were placed into the following five groups: control, model, EA Futu (LI18), EA Hegu (LI4)-Neiguan (PC6), and EA Zusanli (ST36)-Yanglingquan (GB34). The incisional neck pain model was established by making a longitudinal incision along the midline of the neck. The thermal pain threshold (TPT) was measured using a radiation heat detector. The immunoactivities of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), neurokinin-1 receptor (NK-1R), Glu aspartate transporter (GLAST), and Glu transporter-1 (GLT-1) in the dorsal horns (DHs) of the cervico-spinal cord (C2-C5) were detected using immunofluorescence histochemistry. The expression levels of GFAP, Iba-1, GLAST, and GLT-1 mRNAs were determined using quantitative real-time polymerase chain reaction (PCR). The TPT and levels of mRNAs expression and immunoactivity of GLT-1 and GLAST were significantly decreased, and those of Iba-1 and GFAP were significantly increased in the model group than those of the control group (P < 0.05). The activated microgliacytes were gathered around the NK-1R positive neurons, and co-expression of NK-1R and astrocytes was observed in the model group. EA LI18 significantly increased the TPT and expression of GLAST and GLT-1 mRNAs (P < 0.05) and notably decreased the number of Iba-1 positive cells and Iba-l mRNA expression (P < 0.05), whereas GLAST and GLT-1 antagonists inhibited the analgesic effect of EA LI18. However, these effects, except for the downregulation of Iba-1 mRNA, were not observed in the EA ST36-GB34 group. Fewer NK-1R-positive neurons were visible in the spinal DHs in the EA LI18 group, and the co-expression of NK-1R and astrocytes was also lower than that in the three EA groups. Electroacupuncture of LI18 had an analgesic effect in rats with neck incisions, which may be related to its functions in suppressing the neuronal-glial cell interaction through NK-1R and upregulating the expression of GLAST and GLT-1 in the spinal DHs.

Ambient Temperature Is Correlated With the Severity of Neonatal Hypoxic-Ischemic Brain Injury via Microglial Accumulation in Mice.

BackgroundThe pathophysiology of neonatal hypoxic-ischemic encephalopathy (HIE) has been studied in several rodent models to develop novel treatments. Although it is well known that high ambient temperature results in severe HIE, the effect of subtle changes in ambient temperature during a hypoxic-ischemic (HI) insult has not been studied. Therefore, in order to clarify the difference of pathophysiological change among the HIE models due to the influence of small changes in chamber temperature, three-step gradual change of 0.5°C each were prepared in ambient temperature during hypoxic exposure.MethodsBlood flow in the left common carotid artery (CCA) of neonatal mice was interrupted using bipolar electronic forceps under general and local anesthesia. The mice were subsequently subjected to 10% hypoxic exposure for 50 min at 36.0, 36.5, or 37.0°C. A control group was also included in the study. The size of the striatum and hippocampus and the volume reduction rate of the hemisphere in the section containing them on the ischemic side were evaluated using microtubule associated protein 2 (MAP2) immunostaining. The accumulation of Iba1-positive cells was investigated to assess inflammation. Additionally, rotarod and open-field tests were performed 2 weeks after HI insult to assess its effect on physiological conditions.ResultsMAP2 staining revealed that the higher the temperature during hypoxia, the more severe the volume reduction rate in the hemisphere, striatum, and hippocampus. The number of Iba1-positive cells in the ipsilateral lesion gradually increased with increasing temperature, and there was a significant difference in motor function in the 36.5 and 37.0°C groups compared with the sham group. In the open-field tests, there was a significant decrease in performance in the 37.0°C groups compared with the 36.0°C and sham groups.ConclusionsEven a small gradual change of 0.5°C produced a significant difference in pathological and behavioral changes and contributed to the accumulation of Iba1-positive cells. The arrangement of ambient temperature is useful for creating a rodent model with the appropriate severity of the targeted neuropsychological symptoms to establish a novel therapy for HIE.

JAK2/STAT3 pathway regulates microglia polarization involved in hippocampal inflammatory damage due to acute paraquat exposure

ObjectiveTo explore the effects of acute paraquat (PQ) exposure on the phenotypic polarization of hippocampal microglia and its mechanism. MethodsAn acute PQ exposure rat model was established. Male SD rats were exposed to 0, 5, 25, and 50 mg/kg PQ, and brain hippocampal tissue was collected after 1, 3, and 7 days of exposure, respectively. Hippocampal pathological changes were examined by H&E staining, and immunohistochemistry (IHC) was used to detect changes in the number of Iba-1-positive cells, the average number of endpoints, and the average process length. The protein expression of Iba-1 was detected by western blotting. BV-2 microglia were treated with 0, 0.01, 0.025, 0.05, or 0.1 μmol/L PQ for 24 h. ELISA and western blotting assays were performed to detect the expression of TNF-α and IL-1β in vivo and in vitro. The M1 microglia marker iNOS, the M2 microglia marker Arg-1, and the p-JAK2 and p-STAT3 protein were detected by western blotting. JAK2/STAT3 pathway activation role in regulating microglia phenotypic polarization was further validated in vivo and in vitro by JAK2-specific inhibitor AG490 administration. ResultsAfter acute PQ exposure, hippocampal neurons showed pathological changes such as loose arrangement and nuclear pyknosis, the number of Iba-1 positive cells and the expression of Iba-1 protein increased, and the average number of endpoints and average process length of microglia decreased. Histological examination revealed that compared with the control group, in the 50 mg/kg PQ group on the 3rd and 7th day, the expression of TNF-α, IL-1β, and iNOS significantly increased, while that of Arg-1 significantly decreased. p-JAK2 and p-STAT3 expression significantly increased in the 50 mg/kg PQ group on the 1st, 3rd, and 7th day. In vitro, compared with the control group, the expression of TNF-α, IL-1β, iNOS, p-JAK2, and p-STAT3 significantly increased, while Arg-1 expression was significantly reduced in the 0.025, 0.05, and 0.1 μmol/L PQ groups. After AG490 administration, the expression levels of p-JAK2, p-STAT3, iNOS, TNF-α, and IL-1β in the AG490 +PQ group were significantly inhibited in vivo and in vitro compared with the PQ-only group. On the contrary, Arg-1 expression was significantly increased. ConclusionOur results suggest that acute PQ exposure may induce M1-type polarization of hippocampal microglia by activating the JAK2/STAT3 pathway, which in turn releases pro-inflammatory factors such as TNF-α and IL-1β, leading to hippocampal inflammatory damage.

Influence of electroacupuncture on locomotor function and expression of spinal HMGB1 and TLR4 in mice with spinal cord injury

To observe the effect of electroacupuncture(EA)on locomotor activity and the expression of high-mobility group box-1(HMGB1) and Toll-like receptor 4(TLR4) in mice with spinal cord injury(SCI), so as to explore its mechanisms underlying improvement of SCI at the acute stage. Forty-eight female C57BL/6 mice were equally randomized into 3 groups: sham operation, model and EA. The SCI model was established by clamping the spinal cord with a serrefine after laminectomy at the 1st lumbar vertebra(L1). EA (1.5 Hz/7.5 Hz, 1.0 mA) was applied to "Jiaji"(EXH-B2) for 10 min, once a day for 5 and 14 days, separately. The hindlimb locomotor function was assessed by Basso, Beattie, Bresnahan Locomotor Rating Scale (BBB). Histopathological changes of the injured area of the spinal cord were determined by H.E. staining. The expression levels of spinal HMGB1, TLR4, ionized calcium binding adaptor molecule 1(Iba1) proteins were detected by Western blot, and the Iba1-positive microglial cells and HMGB1 and Iba1 co-labelled microglia were displayed by immunofluorescence staining. After SCI, the BBB scores on day 5 and 14 were obviously decreased (P<0.05), and the expression of HMGB1 on day 14, TLR4 on day 5 and 14, the number of Iba1-positive microglia as well as the co-expressed HMGB1/Iba1-positive microglia on day 5 and 14 were significantly increased in the model group relevant to the sham operation group (P<0.05, P<0.01). In the EA intervention group, SCI-induced reduction of BBB scores on day 5 and 14, and increases of the expression of HMGB1 and Iba1 on day 14, and TLR4 on day 5 and 14, and the number of Iba1-positive cells as well as the co-expressed HMGB1/Iba1-positive microglia on day 14 were reversed relevant to the model group (P<0.05,P<0.01). H.E. staining showed a structural disorder with lots of cavities, severe inflammatory infiltration with a large quantity of inflammatory cells, and a reduction of normal neurons in the injured spinal cord tissue in the model group， which was relatively milder, with lower activation of microglia in the EA group. EA can significantly improve locomotor function in SCI mice, which is associated with its effects in suppressing the expression of inflammatory factors such as HMGB1, TLR4, Iba1 and the over-activation of microglia.

Neuroprotective Effects of the FGF21 Analogue LY2405319.

To date, there are no effective treatments for Alzheimer's disease (AD). Thus, a significant need for research of therapies remains. One promising pharmacological target is the hormone fibroblast growth factor 21 (FGF21), which is thought to be neuroprotective. A clinical candidate for medical use could be the FGF21 analogue LY2405319 (LY), which has a specificity and potency comparable to FGF21. The present study investigated the potential neuroprotective effect of LY via PPARγ/apoE/abca1 pathway, which is known to degrade amyloid-β (Aβ) plaques by using primary glial cells and hippocampal organotypic brain slice cultures (OBSCs) from 30- and 50-week-old transgenic APPswe/PS1dE9 (tg) mice. By LY treatment of 52-week-old tg mice with advanced Aβ deposition, we further aimed to elaborate the effect of LY on AD pathology in vivo. LY application to primary glial cells caused an upregulation of pparγ, apoE, and abca1 mRNA expression and significantly decreased number and area of Aβ plaques in OBSCs. LY treatment in tg mice increased cerebral [18F] FDG uptake and N-acetylaspartate/creatine ratio indicating enhanced neuronal activity and integrity. Although LY did not reduce the number of Aβ plaques in tg mice, the number of iba1-positive cells was significantly decreased indicating reduced microgliosis. These data identified LY in vitro as an activator of Aβ degrading genes leading to cerebral Aβ load amelioration in early and late AD pathology. Although Aβ plaque reduction by LY failed in vivo, LY may be used as therapeutic agent to treat AD-related neuroinflammation and impaired neuronal integrity.

Involvement of FGF-2 modulation in the antidepressant-like effects of liquiritin in mice

It has been reported that liquiritin produced an antidepressant-like effect in rodents. However, little information is known regarding its antidepressant activity with the regulation of fibroblast growth factor 2 (FGF-2), a protein maintaining development and maturation of the nervous central system. Therefore, the aim of the present study was to investigate the underlying FGF-2 modulation involved in the antidepressant-like effects of liquiritin. In the present study, mice were orally administrated with liquiritin for 7 days prior to LPS injection. The depressive-like behaviors, levels of FGF-2, number of Iba1 positive cells, expression of proinflammatory cytokines and density of dendritic spines were evaluated. The results showed that liquiritin significantly ameliorated the depressive-like behaviors in mice response to LPS injection. Liquiritin reversed the reduction of FGF-2 levels in the hippocampus of LPS induced mice. In addition, the microglial activation caused by LPS was attenuated by liquiritin, in accordance with downregulation in mRNA levels of proinflammatory cytokines. Moreover, liquiritin also increased the density of dendritic spines in the hippocampus, which was suppressed by LPS. In conclusion, our findings demonstrated that liquiritin exerted the antidepressant-like effects in LPS-induced depression through FGF-2 enhancement by inhibiting neuroinflammation and maintaining synaptogenesis.

Acupuncture inhibits the activation of spinal microglia in the acute uterine cervical distension rats.

Although labor pain is treated clinically by the administration of local anesthetics alone or with opioids in the epidural or spinal spaces, however, the mechanisms of labor pain mechanisms have not been fully elucidated during to the lack of animal models, and the side effects of drugs still existed. Spinal microglia can be activated or mobilized under several pain states, and we want to explore the activation of spinal microglia is involved in the acute uterine cervical distension rats or not. (I) The electromyographic (EMG) response to uterine cervical distension (UCD) was observed. Twenty-four Sprague-Dawley rats were randomly divided into three groups: standard group, sham group, and UCD group (n=8). EMG response to UCD was recorded at 30, 60 and 120 min after distension, respectively. The activation of microglia in the spinal cord at UCD 60 min was seen. Grouping following the first part (n=4), four rats were executed perfusion after distension of 60 min, the T12 to L2 spinal cord segments were removed for immunohistochemical analysis. (II) After successfully implantation of the intrathecal catheter, 36 Sprague-Dawley rats were randomly divided into the PBS group, minocycline group and UCD group (n=12). EMG response to UCD was recorded before distension and after 30, 60, and 120 min after distension (n=8). Four rats of each group were executed perfusion at 60 min after distension, the T12 to L2 spinal cord segments were removed for immunohistochemical analysis. (III) Thirty-six Sprague-Dawley rats were randomly divided into an electrical acupuncture group, non-acupuncture group, and UCD group (n=12). EMG response to UCD was recorded at 30, 60, and 120 min after distension. Four rats of each group were executed at 60 min after distension, and the T12 to L2 spinal cord segments were removed for immunohistochemical analysis to observe the effect of Hegu and Sanyinjiao acupuncture electric stimulation in the activation of spinal microglia. (I) EMG based value of sham group, standard group, and the UCD group were no statistical significance (P>0.05). After UCD, the EMG of the UCD group were increased at 30, 60, 120 min. Compared with fundamental values (P<0.05), which the most apparent EMG change at 60 min after UCD (P<0.05). Sixty min after UCD, compared with the sham group and the standard group, the EMG of the UCD group was higher (P<0.05), but no difference was observed between standard group and sham group (P>0.05). Compared with the sham group, the number of Iba1 (microglia markers)positive cells in thoracic, lumbar spinal cord (T12 to L2) was higher at 60 min after UCD (P<0.05), the most Iba1 labeled cells expressed in IV-V layer and X layer of lumbar spinal cord dorsal horn. (II) EMG based value of UCD group, PBS group, and minocycline group had no significant difference (P>0.05). Sixty min after UCD, compared with the PBS and UCD group, the EMG of the minocycline group was decreased significantly (P<0.05), but there was no difference between the PBS group and UCD group (P>0.05). At 30 and 120 min after UCD, the difference of EMG among the UCD group, PBS group, and minocycline group was no statistical significance (P>0.05). Compared with the PBS and UCD group, the number of Iba1 positive cells at the thoracic, lumbar spinal cord in the minocycline group decreased significantly (P<0.05). But no difference was observed between the PBS group and minocycline group (P>0.05). (III) In the fourth part of the study: EMG based value of electrical acupuncture group, non-acupuncture group, and UCD group were no different (P>0.05). Sixty min after UCD, compared with non-acupuncture and UCD group, the EMG of the acupuncture group was decreased significantly (P<0.05), but no difference was observed between the UCD group and non-acupuncture group (P>0.05). The activation of spinal microglia is involved in the formation of acute visceral pain induced by uterine cervical distension, Electrical acupuncturing Hegu, and Sanyinjiao alleviate pain, and the possible mechanism is inhibiting the activation of spinal microglia in the acute uterine cervical distension rats.

Chronic high-fat diet consumption induces an alteration in plasma/brain neurotensin signaling, metabolic disturbance, systemic inflammation/oxidative stress, brain apoptosis, and dendritic spine loss

Chronic high-fat diet (HFD) consumption caused not only negative effects on obesity and metabolic disturbance, but also instigated several brain pathologies, including dendritic spine loss. In addition, alterations in plasma/brain neurotensin (NT) levels and NT signaling were observed in obesity. However, the mechanistic link between the NT levels in plasma and brain, NT signaling, and peripheral/brain pathologies following prolonged HFD consumption still needs to be elucidated. We hypothesized that an increase in peripheral/brain NT signaling were associated with peripheral/brain pathologies after prolonged HFD consumption. Male Wistar rats (n = 24) were given either a normal diet (ND) or a HFD for 12 and 40 weeks. At the end of each time course, metabolic parameters and plasma NT levels were measured. Rats were then decapitated and the brains were examined the levels of brain NT, hippocampal reactive oxygen species, the number of Iba-1 positive cells, the dendritic spine densities, and the expression of NT-, mitophagy-, autophagy-, and apoptotic-related proteins. The findings showed an increase in the level of plasma NT with dyslipidemia, metabolic disturbances, systemic inflammation/oxidative stress, and hippocampal pathologies in rats fed HFD for 12 and 40 weeks. The expression of brain NT signaling and brain apoptosis were markedly increased after 40 weeks of HFD feeding. These results indicated that the alteration in the level of circulating/brain NT and its downstream signaling were associated with central and peripheral pathologies after long-term HFD intake. Therefore, these alterations in NT level or its signaling could be considered as a therapeutic target in treating obesity.

Pathophysiological Role of TRPM2 in Age-Related Cognitive Impairment in Mice

Aging causes various functional changes, including cognitive impairment and inflammatory responses in the brain. Transient receptor potential melastatin 2 (TRPM2), a Ca2+-permeable channel expressed abundantly in immune cells, exacerbates inflammatory responses. Previously, we reported that TRPM2 on resident microglia plays a critical role in exacerbating inflammation, white matter injury, and cognitive impairment during chronic cerebral hypoperfusion; however, the physiological or pathophysiological role of TRPM2 during age-associated inflammatory responses remains unclear. Therefore, we examined the effects of TRPM2 deletion in young (2–3 months) and older (12–24 months) mice. Compared with young wild-type (WT) mice, middle-aged (12–16 months) WT mice showed working and cognitive memory dysfunction and aged (20–24 months) WT mice exhibited impaired spatial memory. However, these characteristics were not seen in TRPM2 knockout (TRPM2-KO) mice. Consistent with the finding of cognitive impairment, aged WT mice exhibited white matter injury and hippocampal damage and an increase in the number of Iba1-positive cells and amounts of pro-inflammatory cytokines in the brain; these characteristics were not seen in TRPM2-KO mice. These findings suggest that TRPM2 plays a critical role in exacerbating inflammatory responses and cognitive dysfunction during aging.

The Attenuating Effect of Curcumin on Morphine Dependence in Rats: The Involvement of Spinal Microglial Cells and Inflammatory Cytokines.

New evidence suggests an important role for spinal glial cells in the development of opioid dependence. Curcumin, a component of the Curcuma Longa, has shown to act as a suppressor of microglial cells. The main goal of this study was to explore the attenuating effects of curcumin on morphine dependence with a focus on spinal microglial cells and inflammatory cytokines. In order to induce morphine dependence in male Wistar rats, morphine was administered intraperitoneally (i.p.) once daily for 9 days in an increasing dose of 10, 20, and 40 mg/kg. Curcumin (2.5, 5, and 10 mg/kg, i.p.) was given from the days 10th to 18th. Naloxone-precipitated abstinence syndrome was used to assess the behavioral symptoms of morphine dependence. Immunofluorescence staining of Iba1 and ELISA test were used to measure spinal microglial activity and inflammatory cytokines levels, respectively.The results showed that curcumin (2.5, 5, and 10 mg/kg) significantly decreased jumping, leaning, and diarrhea in morphine-dependent rats. In addition, the spinal concentration of TNF-α and IL-6 was reduced by curcumin (2.5, 5, and 10 mg/kg) significantly. Moreover, curcumin showed a potent attenuating effect on the number of Iba1 positive cells in rats which were subjected to morphine dependence. The results of this study demonstrated that curcumin exerts a remarkable reducing effect on morphine dependence in rats. The findings showed that the therapeutic effect of curcumin on morphine dependence is mediated through the suppression of activated microglial cells and reduction of inflammatory cytokines levels in the spinal cord.

Deficiency of α1,6-fucosyltransferase promotes neuroinflammation by increasing the sensitivity of glial cells to inflammatory mediators

Backgroundα1,6-Fucosyltransferase-deficient (Fut8−/−) mice displayed increased locomotion and schizophrenia-like behaviors. Since neuroinflammation is a common pathological change in most brain diseases, this study was focused on investigating the effects of Fut8 in microglia and astrocytes. MethodsBrain tissues were analyzed using immunohistochemical staining. Core fucosylation and protein expression were analyzed using lectin blot and western blot, respectively. Fut8-knockout (KO) cells were established by the CRISPR/Cas9 system. ResultsThe number of Iba-1 positive cells and GFAP positive cells were significantly increased in both untreated and lipopolysaccharide stimulated inflammatory conditional Fut8−/− mice by comparison with both wild-type (Fut8+/+) and hetero (Fut8+/−) mice. Stimulation with pro-inflammatory factors, such as IFN-γ and IL-6, induced expression levels of fucosylation in primary microglia and astrocytes, as well as in glial cell lines. Cell motility and iNOS expression were easily induced by IFN-γ in Fut8-KO BV-2 cells compared with wild-type (WT) cells. In a similar manner, both Fut8-KO C6 cells and primary astrocytes treated with 2-fluoro-L-fucose, a specific inhibitor for fucosylation, showed a higher response to IL-6-stimulated phospho-STAT3 signaling, compared with WT cells. ConclusionsCore fucosylation negatively regulates the states of neuroinflammation by modulating the sensitivity of microglia and astrocytes to inflammatory mediators. The disorders of Fut8−/− mice are caused not only by neurons but also by glial cell dysfunction. General significanceCore fucose is a novel regulator for neuroinflammation in the central nervous system.

The effect of the transition period and postpartum body weight loss on macrophage infiltrates in bovine subcutaneous adipose tissue

The transition period in dairy cattle is characterized by a rapid increase in metabolic demands due to the onset of lactation in parallel with a voluntary drop in dry matter intake, which slowly increases compared with the rapidly increasing milk production. The resulting deficit in energy intake is largely met by lipolysis of adipose tissue stores liberating nonesterified fatty acids (NEFA) as energy substrates to support milk production and for the synthesis of milk fat. Previous work in cattle and other species has documented an increase in adipose tissue macrophages (ATM) during periods of feed restriction and lipolysis; however, alterations in ATM during the transition period have only recently received interest because of the role that adipose tissue remodeling and inflammation may play during this time. The primary objective of this study was to evaluate the number of macrophages in subcutaneous adipose tissue from dairy cattle at multiple time points throughout the transition period. Secondary objectives included the evaluation for potential associations of ATM with changes in body condition score (BCS) and concentrations of circulating NEFA and β-hydroxybutyrate. Holstein cows (n = 25) were enrolled in the study 28 d before expected parturition and fed the same prepartum and postpartum rations for ad libitum consumption. On d 10 before expected parturition, and on d 4 and 21 after calving, subcutaneous adipose tissue biopsies were taken from the paralumbar fossa and preserved in formalin. Paraffin-embedded sections of tissue from each of the 25 cows at the 3 time points (total of 75 samples) were labeled with an immunohistochemical marker of macrophages, ionized calcium-binding adapter molecule 1 (Iba1, also known as allograft inflammatory factor 1). The number of Iba1-positive cells, the number of crown-like structures, and the number of immunopositive aggregates were enumerated in each sample. The number of Iba1-positive macrophages increased by 60 and 93% on d 4 and 21, respectively, when compared with the average prepartum number. Additionally, cows that lost ≥0.50 points of BCS had a 57 and 52% higher number of ATM on d 4 and 21 postpartum, respectively, when compared with cows that lost ≤0.25 points of BCS. No association was found between ATM numbers and NEFA and β-hydroxybutyrate concentrations or milk production in early lactation. Cows experiencing a more pronounced decrease in BCS postpartum had the largest increase in adipose tissue macrophage counts, suggesting that a greater degree of adipose tissue remodeling during the period of greatest nutrient deficit may be associated with higher numbers of ATM.

Gypenosides reverses depressive behavior via inhibiting hippocampal neuroinflammation

Gypenosides, a saponins extract isolated from the Gynostemma pentaphyllum plant, produces neuroprotective effects in the brain. Our previous studies have shown that hippocampal glucocorticoid receptor (GR)-brain-derived neurotrophic factor (BDNF)-TrkB signaling was involved in the antidepressant-like effects of gypenosides. It remains unknown whether gypenosides could alleviate neuroinflammation in depressive-like animals. The aim of the present study was to address this issue in chronic unpredictable mild stress (CUMS). Gypenosides was administrated for four weeks, followed by sucrose preference test and tail suspension test, which were performed to evaluate the effects of gypenosides. The results showed that gypenosides reversed both the decreased sucrose preference and increased immobility time in CUMS mice. In addition, gypenosides also attenuated the increase of pro-inflammatory cytokine levels in the hippocampus of CUMS animals. Furthermore, the activation of NF-κB, as well as its upstream mediators IKKα and IKKβ were inhibited by gypenosides. Last but not the least, CUMS promoted the activation of microglia, while gypenosides suppressed it according to the reduced number of iba1 positive cells. In conclusion, this study demonstrates that gypenosides exhibits the antidepressant-like effects in mice, which may be mediated by the inhibition of microglia and NF-κB signaling in the hippocampus.

Gunn rats with glial activation in the hippocampus show prolonged immobility time in the forced swimming test and tail suspension test.

IntroductionRecent studies imply that glial activation plays a role in the pathogenesis of psychiatric disorders, such as schizophrenia and major depression. We previously demonstrated that Gunn rats with hyperbilirubinemia show congenital gliosis and schizophrenia‐like behavior.MethodsAs it has been suggested that major depression involves glial activation associated with neuroinflammation, we examined whether Gunn rats show depression‐like behavior using the forced swimming test (FST) and the tail suspension test (TST). In addition, we quantitatively evaluated both microgliosis and astrogliosis in the hippocampus of Gunn rats using immunohistochemistry analysis of the microglial marker ionized calcium‐binding adaptor molecule (Iba) 1 and the astrocytic marker S100B.ResultsBoth the FST and TST showed that immobility time of Gunn rats was significantly longer than that of normal control Wistar rats, indicating that Gunn rats are somewhat helpless, a sign of depression‐like behavior. In the quantification of immunohistochemical analysis, Iba1immunoreactivity in the dentate gyrus (DG), cornu ammonis (CA) 1, and CA3 and the number of Iba1‐positive cells in the CA1 and CA3 were significantly increased in Gunn rats compared to Wistar rats. S100B immunoreactivity in the DG, CA1, and CA3 and the number of S100B‐positive cells in the DG and CA3 were significantly increased in Gunn rats compared to Wistar rats.ConclusionOur findings suggest that both microglia and astrocyte are activated in Gunn rats and their learned helplessness could be related to glial activation.