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【Objective】 To clarify the role and molecular mechanism of Tanshinone ⅡA (TanⅡA) in the pathological integration of granule cells in the dentate gyrus (DG) by using the mouse model of temporal lobe epilepsy (TLE). 【Methods】 Status epilepticus (SE) was induced in the mice with pilocarpine and treated with TanⅡA 5 mg/kg. After two months, Morris water maze was used to examine the spatial learning and memory ability and video surveillance was used to monitor spontaneous seizures. The DG was removed for staining of Timm, Prox-1, DCX and SynⅠ. PTEN, p-AKT, and p-S6 expressions were observed by Western blotting. 【Results】 TanⅡA decreased Timm score, SynⅠ, PSD-95 and pS6 levels, and increased the level of PTEN in the DG, and attenuated the formation of mossy fiber sproutings and basal dendrites of the granule cells. Video surveillance showed that TanⅡA reduced the frequency of Racine’ grade 5 seizures. 【Conclusion】 TanⅡA can effectively attenuate the abnormal integration of the granule cells in the DG by regulating PTEN/AKT/mTOR pathway and thus plays an anti-epileptic role.
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Objective:To evaluate the role of the sodium leak channel (NALCN) in the hippocampal dentate gyrus (DG) in the social behavior of mice.Methods:Thirty-nine male wild-type C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were used in this study. Three mice were sacrificed to verify the expression and co-expression of NALCN with neuronal nuclear antigen (NeuN) in the hippocampal DG using the immunofluorescent staining. The remaining 36 mice were divided into 2 groups ( n=18 each) by the random number table method: control group (group C) and NALCN gene knockdown group (group KO). NALCN-shRNA virus was injected in group KO, and scrambled-shRNA virus was injected in group C. The three box social test and open field test were performed at 3 weeks after the virus injection. Mice were sacrificed under anesthesia after the behavioral test, hippocampal tissues were collected, and the injection location of the virus was verified with a fluorescence microscope, and the NALCN protein and mRNA expression in the hippocampal DG was detected by Western blot and real-time polymerase chain reaction, respectively. Results:NALCN and NeuN co-expressed a lot on the same neuron in the hippocampal DG of mice, indicating that NALCN was widely expressed on the neurons in the hippocampal DG. Compared with group C, the expression of NALCN and mRNA in the hippocampal DG was significantly down-regulated, and the social novelty preference disappeared ( P<0.05), and no significant change was found in the social ability and each parameter in the open field test in group KO ( P>0.05). Conclusions:NALCN in the hippocampal DG is involved in the regulation of social memory in mice, and the down-regulated expression of NALCN can lead to the loss of social novelty preference in mice.
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Objective@#Neonatal exposure to propofol has been reported to cause neurotoxicity and neurocognitive decline in adulthood; however, the underlying mechanism has not been established.@*Methods@#SD rats were exposed to propofol on postnatal day 7 (PND-7). Double-immunofluorescence staining was used to assess neurogenesis in the hippocampal dentate gyrus (DG). The expression of p-Akt and p27 were measured by western blotting. The Morris water maze, novel object recognition test, and object location test were used to evaluate neurocognitive function 2-month-old rats.@*Results@#Phosphorylation of Akt was inhibited, while p27 expression was enhanced after neonatal exposure to propofol. Propofol also inhibited proliferation of neural stem cells (NSCs) and decreased differentiation to neurons and astroglia. Moreover, the neurocognitive function in 2-month-old rats was weakened. Of significance, intra-hippocampal injection of the Akt activator, SC79, attenuated the inhibition of p-AKT and increase of p27 expression. SC79 also rescued the propofol-induced inhibition of NSC proliferation and differentiation. The propofol-induced neurocognition deficit was also partially reversed by SC79.@*Conclusion@#Taken together, these results suggest that neurogenesis is hindered by neonatal propofol exposure. Specifically, neonatal propofol exposure was shown to suppress the proliferation and differentiation of NSCs by inhibiting Akt/p27 signaling pathway.
Subject(s)
Animals , Rats , Cell Proliferation , Hippocampus/metabolism , Neural Stem Cells , Propofol/toxicity , Proto-Oncogene Proteins c-akt/metabolism , Rats, Sprague-Dawley , Signal TransductionABSTRACT
Objective:To evaluate the relationship between Na + leak current channel (NALCN) in hippocampal dentate gyrus (DG) region and cognitive function in mice. Methods:Thirty-nine male wild type C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were studied.Three mice were sacrificed to verify the expression of NALCN co-localized with neuronal nuclear antigen (NeuN) in the hippocampal DG region through immunofluorescence technique.The remaining 36 mice were divided into 2 groups ( n=18 each) by the random number table method: control group (group C) and NALCN gene knockout group (group KO). NALCN-shRNA virus was injected in hippocampal DG region in group KO, and scrambled-shRNA virus was injected in group C. Three weeks after virus injection, behavioral tests (Y maze test and open field test) were performed, then the animals were sacrificed, and the hippocampal tissues were removed for determination of the expression of NALCN protein and mRNA using Western blot and real-time polymerase chain reaction. Results:NALCN and NeuN colocalized a lot on the same neuron in the hippocampal DG region of mice, and NALCN was widely expressed in the hippocampal DG region.Compared with group C, the expression of NALCN protein and mRNA was significantly down-regulated, the times of entering the new arm were reduced, the duration of staying at the new arm was shortened ( P<0.05), and no significant change was found in the parameters mentioned above in the open field test in group KO ( P>0.05). Conclusions:NALCN in the hippocampal DG region is involved in the regulation of cognitive function in mice, and the down-regulation of NALCN may lead to cognitive decline.
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Objective:To investigate the effects of hippocampal injection of tyrosine kinase receptor binding protein B3(Ephrin-B3) agonist on spontaneous seizures and the expression of hippocampal secretory glycoprotein (Reelin) and phosphorylated adaptor protein (p-Dab1) in epileptic model rats.Methods:Seventy-eight rats were randomly divided into control group and model group according to body mass matching with 39 rats in each group.The rats in control group were fed normaly, and the rats in model group were established epilepsy model by intraperitoneal injection of lithium chloride pilocarpine. The hippocampal tissues were taken in the acute phase (7 days), quiescent phase (14 days) and chronic phase (60 days) after the successful induction of status epilepticus. The levels of Reelin protein and p-Dab1 protein in the hippocampal tissues of epileptic model rats and normal rats were detected by immunohistochemistry and Western blot.And thirteen rats were randomly selected at each time point. Another 48 rats were randomly divided into normal Fc-control group, normal EphB3-Fc group, epilepsy Fc-control group and epilepsy EphB3-Fc group, with 12 rats in each group. Rats in the first two groups were fed normally, and those in the latter two groups were established epileptic model. Seven days after modeling, all rats were injected into bilateral hippocampus with EphB3-Fc (Ephrin-B3 agonist) and FC control (control agent of Ephrin-B3 agonist) according to the grouping, once a day for 7 days. After administration, the changes of behavior and EEG were observed within two weeks. At the same time, the expression of Reelin protein and p-Dab1 protein were detected by immunohistochemistry and Western blot. SPSS 21.0 was used for statistical analysis, One-way ANOVA was used for multi group comparison, and Tukey's test was used for pairwise comparison.Results:The results of immunohistochemistry and Western blot showed that compared with the control group, the levels of Reelin and p-Dab1 protein in hippocampus of model group decreased significantly at 7, 14 and 60 days after epilepsy (all P<0.01). The results of immunohistochemistry showed that compared with epilepsy Fc-control group, the levels of p-Dab1 ((0.41±0.04), (0.58±0.06), P<0.05) in epilepsy EphB3-Fc group increased significantly.Western blot result showed that the level of p-Dab1 in epilepsy EphB3-Fc group increased compared with that of epilepsy Fc-control group (1.34±0.04), (2.26±0.10), P<0.01). Compared with epilepsy Fc-control group, epilepsy EphB3-Fc group showed less average seizure duration ((39.00±1.79)s, (26.50±1.87)s; t=23.21, P<0.01), less frequencies ((2.00±0.89), (0.50±0.55); t=2.32, P<0.01) and less latent period ((6.33±1.37)day, (12.50±1.87)day; t=2.52, P<0.01) in spontaneous recurrent seizures. Compared with epilepsy Fc-control group, epilepsy EphB3-Fc group showed lower average amplitude ((37.30±1.21)μV, (29.00±1.41)μV; t=25.14, P<0.01), less average seizure duration ((5.35±0.19)s, (2.35±0.19)s; t=3.13, P<0.01). Conclusion:Ephrin-B3 alleviated spontaneous recurrent seizures by upregulating Reelin and p-Dab1 in temporal lobe epilepsy rat.
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The hippocampus plays an important role in fear learning and memory processing.It is a key brain area in the pathogenesis of post-traumatic stress disorder (PTSD). Neuroimaging studies have confirmed that the hippocampal structure and functional connectivity of patients with PTSD are abnormal, but the changes in hippocampal subregions are still unclear.The results of brain structure studies showed that the cornu ammonis and dentate gyrus atrophy in adult PTSD patients and the symptom of re-experience may be related to pattern separation dysfunction caused by reduced dentate gyrus neurogenesis.Among children diagnosed with PTSD, there is no significant change found in cornu ammonis and dentate gyrus, while atrophy in presubiculum was observed, which could result in fear extinction and deficits in episodic memory.The alteration of hippocampal volume in PTSD may have a gender-specific lateralization phenomenon.The results of brain function studies show that the functional connectivity of hippocampal subregions in PTSD patients is selectively damaged, especially the connectivity with key brain regions in the default mode network is reduced.This article systematically reviews the structural and functional connectivity changes of hippocampal subregions in patients with PTSD from the perspective of neuroimaging, in order to promote the understanding of the pathogenesis of PTSD and identify the therapeutic targets of hippocampal subregions.
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SUMMARY: This study aims to investigate the Effects of Titanium dioxide nanoparticles (TiO2 NPs) on the stereological parameters in the dentate gyrus and the morphology of granular hippocampal neurons in adult mice. Adult male mice (n=20, weight average: 45 g) were randomly divided into four groups including: group receiving saline (controls), low-dose (LD) 2.5 mg/kg TiO TiO2 NPs, medium-dose (MD) 5 mg/kg TiO2 NPs and high-dose (HD) 10 mg/kg TiO2 NPs, daily using gavage for 35 days. To estimate the volume of the hippocampus, dentate gyrus, and sub-layers of dentate gyrus the Cavalieri principle was used. The physical dissector was used to determine the numerical density of dentate gyrus granular cells. For analyzing the morphology of dentate gyrus granular cells the qualitative Golgi staining was used. Our data showed that the total volume of the hippocampus, dentate gyrus and its sublayers including molecular, granular and polymorph in TiO2 treated mice decreased significantly compared to the control group. Moreover, the total number and numerical density of dentate gyrus granular sub layer cells showed a significant reduction in all three experimental groups compared to the control group. The granular cells of the dentate gyrus had shorter dendritic length and decreased dendritic branches in the TiO2-treated in comparison with the control mice. These data can justify the disorders related to memory, learning and hippocampus neurons damages due to using of TiO2 NPs.
RESUMEN: En este estudio se analizaron los efectos de las nanopartículas de dióxido de titanio (TiO2 NP) sobre los parámetros estereológicos en el giro dentado y la morfología de las neuronas granulares del hipocampo en ratones adultos. Se dividieron aleatoriamente ratones machos adultos (n = 20, promedio de peso: 45 g) en cuatro grupos: grupo que recibió solución salina (controles), dosis baja (LD) 2,5 mg/kg NP de TiO2, dosis media (MD) 5 mg/kg de NP de TiO2 y dosis altas (HD) de 10 mg/kg de NP de TiO2, por vía utilizando sonda durante 35 días. Para estimar el volumen del hipocampo, el giro dentado y las subcapas del giro dentado se utilizó el principio de Cavalieri. Se utilizó el disector físico para determinar la densidad numérica de las células granulares del giro dentado. Para analizar la morfología de las células granulares del giro dentado se usó la tinción cualitativa de Golgi. Nuestros datos mostraron que el volumen total del hipocampo, el giro dentado y sus subcapas, incluyendo la molecular, granular y polimorfos, en ratones tratados con TiO2, disminuyó significativamente en comparación con el grupo de control. Además, el número total y la densidad numérica de las células de la subcapa granular del giro dentado mostró una reducción significativa en los tres grupos experimentales en comparación con el grupo control. Las células granulares del giro dentado tenían una longitud dendrítica menor y ramas dendríticas disminuidas en los ratones tratados con TiO2 en comparación con los ratones del grupo control. Estos datos pueden justificar los trastornos relacionados con la memoria, el aprendizaje y los daños en las neuronas del hipocampo debido al uso de NP de TiO2.
Subject(s)
Animals , Male , Mice , Titanium/pharmacology , Dentate Gyrus/drug effects , Nanoparticles , Hippocampus/drug effectsABSTRACT
ABSTRACT Induction of long-term potentiation (LTP) increases the storage capacity of synapses in the hippocampal dentate gyrus (DG). Irisin is a myokine generated from FNDC5 (a gene precursor) during exercise. Although intra-cornu ammonis 1 administration of irisin fortifies LTP in mice with Alzheimer's disease, the effects of intra-DG injection of irisin on the LTP in rats remains to be elucidated in vivo. In this study, male Wistar rats were randomly divided into a control group (saline), irisin (0.5, 1, and 1.5 μg/rat), and dimethyl sulfoxide (DMSO). After treatment, the population spike (PS) amplitude and slope of excitatory postsynaptic potentials (EPSP) were measured in the DG of rats in vivo. Moreover, following completion of the experiments, the stimulating and recording sites in the hippocampus were confirmed histologically from brain sections. Furthermore, biochemical assays like malondialdehyde (MDA), total antioxidant capacity (TAC), and total oxidant status (TOS) were evaluated (the antioxidant markers were analyzed in the plasma). Our results suggest that all doses of irisin (0.5, 1, 1.5 μg/rat) caused an increase in the EPSP slope and PS amplitude when compared with the control group. In addition, the results obtained showed that irisin decreased TOS and MDA levels while increasing TAC levels as a marker of lipid peroxidation in plasma. The present report provides direct evidence that irisin affects the activity-dependent synaptic plasticity in the dentate gyrus.
RESUMO A indução de potenciação de longo prazo (LTP) aumenta a capacidade de armazenamento das sinapses no giro denteado (DG) do hipocampo. A irisina é uma miocina gerada a partir do FNDC5 (um precursor genético) durante o exercício. Embora a administração intra-Cornu Ammonis1 de irisina fortaleça a LTP em camundongos com doença de Alzheimer, os efeitos da injeção intra-denteada de irisina sobre a LTP em ratos ainda precisam ser elucidados in vivo. Neste estudo, ratos Wistar machos foram divididos aleatoriamente em um grupo controle (solução salina), irisina (0,5, 1 e 1,5 μg / rato) e dimetilsulfóxido (DMSO). Após o tratamento, a amplitude do pico populacional (PS) e a variação dos potenciais pós-sinápticos excitatórios (EPSP) foram medidos no DG de ratos in vivo. Além disso, após a conclusão das experiências, os locais de estimulação e registro no hipocampo foram confirmados histologicamente a partir de secções do cérebro. Adicionalmente, ensaios bioquímicos como malondialdeído (MDA), capacidade antioxidante total (TAC) e status oxidante total (TOS) foram avaliados (os marcadores antioxidantes foram analisados no plasma). Nossos resultados sugerem que todas as doses de irisina (0,5, 1, 1,5 μg / rato) causaram um aumento na variação da EPSP e na amplitude da PS quando comparadas com o grupo controle. Além disso, os resultados obtidos mostraram que a irisina diminuiu os níveis de TOS e MDA, enquanto aumentou os níveis de TAC como um marcador da peroxidação lipídica no plasma. O presente estudo fornece evidências diretas de que a irisina afeta a plasticidade sináptica dependente de atividade no DG.
Subject(s)
Animals , Male , Neuropeptides/administration & dosage , Fibronectins/administration & dosage , Long-Term Potentiation/drug effects , Dentate Gyrus/drug effects , Microinjections/methods , Reference Values , Time Factors , Lipid Peroxidation , Random Allocation , Reproducibility of Results , Rats, Wistar , Brain-Derived Neurotrophic Factor/analysis , Brain-Derived Neurotrophic Factor/drug effects , Excitatory Postsynaptic Potentials/drug effects , Malondialdehyde/blood , Antioxidants/analysisABSTRACT
La isquemia cerebral es el tipo de accidente cerebrovascular más común, generando altas tasas de mortalidad y morbilidad a nivel mundial. El entendimiento de la fisiopatología de la lesión cerebral ha requerido de la implementación de modelos experimentales que permitan evaluar los fenómenos celulares, sobre todo aquellos a largo plazo. Por tal razón, el objetivo del presente trabajo fue evaluar las áreas exofocales a un mes y cuatro meses post-isquemia cerebral en un modelo experimental. Ratas Wistar fueron sometidas a una isquemia focal transitoria (t-MCAo) y un grupo fueron sacrificados al mes y otro grupo a los cuatro meses post-isquemia para su posterior análisis histológico. Los cortes fueron teñidos con Nissl y se realizó inmunohistoquímica de la proteína Tau. Nuestros resultados muestran tres áreas de lesión exofocal tanto al mes como a los cuatro meses post-isquemia: el giro dentado, la amígdala y el tálamo. Estas regiones se han asociado al control emocional, lo cual sugiere que a largo término post-isquemia se tengan en cuenta hallazgos clínicos que evalúen cambios emocionales en los pacientes que han sufrido un evento isquémico cerebral.
Cerebral ischemia is the most common type of stroke, which generates high mortality and morbidity rates worldwide. The understanding of the pathophysiology of brain injury has required the implementation of experimental models that allow the evaluation of cellular phenomena, especially those in the long-term. For this reason, the objective of the present work was to evaluate the exofocal areas at one month and four months after cerebral ischemia. Wistar rats were subjected to transient focal ischemia (t-MCAo) and one group was sacrificed one month and another group at four months' post-ischemia for subsequent histological analysis. The cuts were stained with Nissl and immunohistochemistry of the Tau protein was performed. Our results show three areas of exofocal lesion both one month and four months' post-ischemia: the thalamus, the dentate gyrus, and the amygdala. These regions have been associated with emotional control, which suggests that in the long-term post-ischemia clinical findings that evaluate emotional changes in patients who have suffered a cerebral ischemic event should be considered.
Subject(s)
Animals , Rats , Thalamus/pathology , Brain Ischemia/pathology , Dentate Gyrus/pathology , Amygdala/pathology , Immunohistochemistry , Disease Models, AnimalABSTRACT
MicroRNA-132 (miR-132), a small RNA that regulates gene expression, is known to promote neurogenesis in the embryonic nervous system and adult brain. Although exposure to psychoactive substances can increase miR-132 expression in cultured neural stem cells (NSCs) and the adult brain of rodents, little is known about its role in opioid addiction. So, we set out to determine the effect of miR-132 on differentiation of the NSCs and whether this effect is involved in opioid addiction using the rat morphine self-administration (MSA) model. We found that miR-132 overexpression enhanced the differentiation of NSCs in vivo and in vitro. Similarly, specific overexpression of miR-132 in NSCs of the adult hippocampal dentate gyrus (DG) during the acquisition stage of MSA potentiated morphine-seeking behavior. These findings indicate that miR-132 is involved in opioid addiction, probably by promoting the differentiation of NSCs in the adult DG.
Subject(s)
Animals , Male , Cell Differentiation , Cell Line, Tumor , Dentate Gyrus , Metabolism , Gene Expression Regulation , MicroRNAs , Metabolism , Neural Stem Cells , Metabolism , Opioid-Related Disorders , Metabolism , Rats, Sprague-DawleyABSTRACT
Bacopa monnieri is a medicinal plant with a long history of use in Ayurveda, especially in the treatment of poor memory and cognitive deficits. In the present study, we hypothesized that Bacopa monnieri extract (BME) can improve memory via increased cell proliferation and neuroblast differentiation in the dentate gyrus. BME was administered to 7-week-old mice once a day for 4 weeks and a novel object recognition memory test was performed. Thereafter, the mice were euthanized followed by immunohistochemistry analysis for Ki67, doublecortin (DCX), and phosphorylated cAMP response element-binding protein (CREB), and western blot analysis of brain-derived neurotrophic factor (BDNF). BME-treated mice showed moderate increases in the exploration of new objects when compared with that of familiar objects, leading to a significant higher discrimination index compared with vehicle-treated mice. Ki67 and DCX immunohistochemistry showed a facilitation of cell proliferation and neuroblast differentiation following the administration of BME in the dentate gyrus. In addition, administration of BME significantly elevated the BDNF protein expression in the hippocampal dentate gyrus, and increased CREB phosphorylation in the dentate gyrus. These data suggest that BME improves novel object recognition by increasing the cell proliferation and neuroblast differentiation in the dentate gyrus, and this may be closely related to elevated levels of BDNF and CREB phosphorylation in the dentate gyrus.
Subject(s)
Animals , Mice , Bacopa , Blotting, Western , Brain-Derived Neurotrophic Factor , Cell Proliferation , Cognition Disorders , Cyclic AMP Response Element-Binding Protein , Dentate Gyrus , Discrimination, Psychological , Immunohistochemistry , Memory , Neurogenesis , Phosphorylation , Plants, MedicinalABSTRACT
Objective: To observe the changes of dopamine (DA) levels in the hippocampal dentate gyrus (DG) region of the rats during the establishment and extinction process of active avoidance conditioned reflex, and to investigate the effect of D1 receptor in the active avoidance learning of the rats and its mechanism. Methods: A total of 24 male SD rats were randomly divided into non-training group, training group, control group and SCH group (n= 6). The rats in training group were trained for active avoidance whereas the rats in non-training group were only put into the shuttle box without training, and then the DA levels in extracellular fluid in DG region of the rats in two groups were measured. In control and SCH groups, the saline or SCH-23390 was injected into the DG region of the rats before the active avoidance training, and then the glutamate (Glu) levels and the field excitatory postsynaptic potential (fEPSP) amplitudes in extracellular fluid in DG region of the rats in two groups were examined. The rates of active avoidance of the rats were recorded by behavioral analysis system of the shuttle box. The levels of DA and Glu in DG region of the rats were measured by microdialysis and HPLC techniques, and the amplitude of fEPSP in DG region of the rats was examined by electrophysiological recording. Results: The DA level in DG region of the rats in training group was gradually increased during the establishment process and was gradually decreased during the extinction process of conditioned reflex; compared with the 1st day, the DA level in DG region of the rats on the 5th day was markedly increased (P0. 05). In control group, the rats reached the establishment criterion on the 5th day (active avoidance rate > 65%) and reached the criterion of extinction on the 7th day (active avoidance rate 0. 05). Compared with control group, the Glu level and fEPSP amplitude of the rats in SCH group on the 5th day were markedly decreased (P<0. 05). Conclusion: DA in hippocampal DG region of the rats can facilitate the active avoidance learning via activation of D1 receptors, and its mechanism is associated with the enhancement of Glu level and synaptic transmission efficiency.
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OBJECTIVE: To observe the effect of acupuncture and moxibustion (AM) on learning-memory ability and expression of amyloid beta (Aβ) in the hippocampal dentate gyrus (DG) of Alzheimer's disease (AD) rats, so as to explore its mechanism underlying improvement of AD. METHODS: Forty male Wistar rats were randomly divided into normal, sham operation, model and AM groups (n＝10 in each). The AD model was established by bilateral hippocampal injection of Aβ1-42(5 µL). The AM was applied at "Baihui" (GV 20) and "Shenshu" (BL 23) for 15 min, once daily for 12 times. Morris water maze tests were used to assess the rats' learning-memory ability. The levels of serum Aβ1-42 and Aβ internalizing enzymes including transthyretin (TTR), lipoprotein lipase (LPL), alpha 2 macroglobulin (α 2M) and apolipoprotein E (ApoE) were detected by ELISA. The expression of Aβ1-42 in the hippocampal DG was detected by immunohistochemistry. RESULTS: Compared with the sham operation group, the average escape latency of location navigation test was significantly prolonged in the first 5 days and the last 3 days (P0.05). CONCLUSION: AM can improve the learning-memory ability of AD rats, which may be related to its effects in up-regulating the contents of serum Aβ internalizing enzymes and promoting the clearance of hippocampal Aβ. It suggests a protective role of AM on hippocampal neurons.
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Objective To evaluate the effects of dexmedetomidine on the expression of c-fos in hippocampus and dentate gyrus in a rat model of endotoxic shock.Methods Thirty-five pathogen-free healthy male Sprague-Dawley rats,aged 3-4 months,weighing 250-300 g,were divided into 5 groups (n =7 each) using a random number table:normal saline group (group NS),dexmedetomidine group (group D),endotoxic shock group (group ES),low-dose dexmedetomidine plus lipopolysaccharide (LPS) group (group LD) and high-dose dexmedetomidine plus LPS group (group HD).Dexmedetomidine 0.5 μg/kg was injected via the tail vein in D and LD groups,and dexmedetomidine 4.5 μg/kg was given in group HD.Normal saline 0.5 ml/kg was injected in NS and ES groups,5 min later normal saline 0.5 ml/kg was injected in NS and D groups and LPS 5 mg/kg was injected in the other groups,and the injection time was 10 min in all groups.Rats were sacrificed at 6 h after LPS injection,brains were removed,and the hippocampus and dentate gyrus were isolated for detection of the expression of c-fos by immunohistochemistry.Results Compared with group NS or group D,the expression of c-fos in the hippocampus and dentate gyrus was significantly up-regulated in group ES (P＜0.05).Compared with group LPS,the expression of c-fos in the hippocampus and dentate gyrus was significantly down-regulated in LD and HD groups (P＜0.05).Compared with group LD,the expression of c-fos in hippocampal CA1 and CA3 areas was significantly down-regulated in group HD (P＜0.05).Conclusion The neuroprotective mechanism of dexmedetomidine is related to inhibiting the up-regulated expression of c-fos in the hippocampus and dentate gyrus in a rat model of endotoxic shock.
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Objective To investigate the neurodevelopmental toxicity of ACR by studying the expression of DCX and GAP-43 in the hippocampal dentate gyrus of rats after maternal exposure to acrylamide. Methods Pregnant rats were randomly divided into low-dose ACR(4.5 mg/kg),medium-dose(9 mg/kg),high dose groups(18 mg/kg)and the control group(0 mg/kg),8 in each group,and were exposed to toxicant from gestation-al day 15 to postnatal day 13. All rats and their pups were killed on postnatal day 14. ABC immunohistochemistry was used to detect the expression of GFAP in the hippocampus of mother rats and offspring. Results Compared with the control group,the expression of DCX and GAP-43 in hippocampus dentate gyrus of the pregnant rats in middle and high dose groups was significantly decreased(P < 0.05). Conclusion ACR may interfere with the growth and development of neurons by reducing the expression of DCX and GAP-43.
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Objective:To explore the effects of chronic restraint stress (CRS) on the abilities of spatial learning and memory and the levels of excitatory amino acids in the hippocampal dentate gyrus (DG) in the old rats,and to investigate the neurochemical mechanism of CRS in affecting the spatial learning and memory abilities.Methods:Sixteen male SD rats (18 months old) were randomly divided into control group (n =8) and CRS group (n=8),and the rats in CRS group received CRS 2 h every day for 30 d.And then the spatial learning and memory abilities of rats were measured by Morris water maze (MWM) test,and the extracellular levels of excitatory amino acids including asparate (Asp) and glutamate (Glu) in the DG were simultaneously determined by in vivo microdialysis and HPLC.The levels of corticosterone (CORT) and epinephrine (EPI) in serum of the rats wereexamined by ELISA assay.Results:In CRS group,the escape latencies on the 2nd-4th days were significantly increased and the percentage of time spent in target quadrant on the 5th day was markedly decreased in MWM test compared with control group (P＜0.05).Compared with before training,the extracelluar level of Asp in the DG in control group was significantly increased on the 2nd day in MWM test;compared with control group,the extracelluar level of Asp in the DG in CRS group was significantly decreased on the 3rd day in MWM test (P＜0.05).Compared with before training,the Glu levels in the DG in MWM test in both control and CRS groups were markedly increased (P＜0.05),but there was no significant difference between two groups (P＞0.05).Compared with control group,the levels of CORT and EPI in the serum of the rats in CRS group were significantly increased (P＜0.05).Conclusion:CRS impairs the spatial learning and memory abilities in the old rats,which may be related to the decrease of Asp level in the hippicampal DG of the rats.
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Objective: To explore the effects of chronic restraint stress (CRS) on the abilities of spatial learning and memory and the levels of excitatory amino acids in the hippocampal dentate gyrus (DG) in the old rats, and to investigate the neurochemical mechanism of CRS in affecting the spatial learning and memory abilities. Methods: Sixteen male SD rats (18 months old) were randomly divided into control group (n=8) and CRS group (n=8), and the rats in CRS group received CRS 2 h every day for 30 d. And then the spatial learning and memory abilities of rats were measured by Morris water maze (MWM) test, and the extracellular levels of excitatory amino acids including asparate (Asp) and glutamate (Glu) in the DG were simultaneously determined by in vivo microdialysis and HPLC. The levels of corticosterone (CORT) and epinephrine (EPI) in serum of the rats were examined by ELISA assay. Results: In CRS group, the escape latencies on the 2nd-4th days were significantly increased and the percentage of time spent in target quadrant on the 5th day was markedly decreased in MWM test compared with control group (P0. 05). Compared with control group, the levels of CORT and EPI in the serum of the rats in CRS group were significantly increased (P<0. 05). Conclusion: CRS impairs the spatial learning and memory abilities in the old rats, which may be related to the decrease of Asp level in the hippicampal DG of the rats.
ABSTRACT
In the present study, we compared the cell-specific expression and changes protein levels in the glucose transporters (GLUTs) 1 and 3, the major GLUTs in the mouse and gerbil brains using immunohistochemistry and Western blot analysis. In both mouse and gerbils, GLUT1 immunoreactivity was mainly found in the blood vessels in the dentate gyrus, while GLUT3 immunoreactivity was detected in the subgranular zone and the molecular layer of the dentate gyrus. GLUT1-immunoreactivity in blood vessels and GLUT1 protein levels were significantly decreased with age in the mice and gerbils, respectively. In addition, few GLUT3-immunoreactive cells were found in the subgranular zone in aged mice and gerbils, but GLUT3-immunoreactivity was abundantly found in the polymorphic layer of dentate gyrus in mice and gerbils with a dot-like pattern. Based on the double immunofluorescence study, GLUT3-immunoreactive structures in gerbils were localized in the glial fibrillary acidic protein-immunoreactive astrocytes in the dentate gyrus. Western blot analysis showed that GLUT3 expression in the hippocampal homogenates was slightly, although not significantly, decreased with age in mice and gerbils, respectively. These results indicate that the reduction in GLUT1 in the blood vessels of dentate gyrus and GLUT3 in the subgranular zone of dentate gyrus may be associated with the decrease in uptake of glucose into brain and neuroblasts in the dentate gyrus. In addition, the expression of GLUT3 in the astrocytes in polymorphic layer of dentate gyrus may be associated with metabolic changes in glucose in aged hippocampus.
Subject(s)
Animals , Mice , Aging , Astrocytes , Blood Vessels , Blotting, Western , Brain , Dentate Gyrus , Fluorescent Antibody Technique , Gerbillinae , Glucose Transport Proteins, Facilitative , Glucose Transporter Type 1 , Glucose , Hippocampus , ImmunohistochemistryABSTRACT
OBJECTIVE To investigate the effect of overexpession of 18 ku translocator protein (TSPO) on the hippocampal dentate gyrus. METHODS Lentiviral (LV) vectors containing TSPO or the lentiviral sequence were infused into the hippocampus bilateral dentate gyri (2 × 108 TU · mL-1,1 μL per side)of mice. Behavioral tests were carried out. The anxiolytic-like behavior of mice was examined by such means as the elevated plus maze test , the staircase test , light dark box test for 12, 14 and 16 d, two behavioral despair models, tail suspension test and the forced swimming test for 16 and 18 d,respec?tively. Western blotting and ELISA were used to evaluate the TSPO expression and the concentration of allopregnanolone in hippocampal tissue (3 mm in diameter around the injection site on both sides) at the end of tests. RESULTS The results of behavioral experiments showed that TSPO overexpression group deneloped anxiolytic and antidepression-like behavior. LV-TSPO significantly increased the retention time in the central area〔14 ± 4 vs (25 ± 12)s,P<0.05〕. LV-TSPO significantly increased the percentage of entry into open arms entries percentage and the percentage of time spent in open arms time without changing total entries and total time in the elevated plus-maze test〔(13±8)%vs (26±18)%, P<0.05;(6 ± 6)%vs (27 ± 6)%, P<0.05)〕. LV-TSPO significantly decreased the number of rearings without changing the number of steps in staircase test (21±7 vs 12±5,P<0.05). LV-TSPO increased entries into the light area and retention time in light-dark transition test〔(18 ± 8)% vs (26 ± 7)%, P<0.05;72 ± 36 vs (191 ± 90)s, P<0.05)〕but significantly decreased immobility time in the tail suspension test and forced swimming test〔94±33 vs (36±20)s, P<0.01;137±36 vs (90±37)s, P<0.05)〕, without excitatory or inhibitory actions on the central nervous system. At the same time, the level of TSPO expression in hippocampal tissues (3 mm in diameter around the injection site on both sides) was significantly increased, so did the concentration of allopregnanolone (P<0.05). CONCLUSION Overexpression of TSPO in the hippocamus dentate gyrus of mice can induce anxiolytic and antidepressant-like behavior, and the downstream allo?pregnanolone biosynthesis at least partially mediates the behavioral effects.
ABSTRACT
The sustained tonic currents (I(tonic)) generated by γ-aminobutyric acid A receptors (GABA(A)Rs) are implicated in diverse age-dependent brain functions. While various mechanisms regulating I(tonic) in the hippocampus are known, their combined role in I(tonic) regulation is not well understood in different age groups. In this study, we demonstrated that a developmental increase in GABA transporter (GAT) expression, combined with gradual decrease in GABA(A)R α₅ subunit, resulted in various I(tonic) in the dentate gyrus granule cells (DGGCs) of preadolescent rats. Both GAT-1 and GAT-3 expression gradually increased at infantile (P₆₋₈ and P₁₃₋₁₅) and juvenile (P₂₀₋₂₂ and P₂₇₋₂₉) stages, with stabilization observed thereafter in adolescents (P₃₄₋₃₆) and young adults (P₄₁₋₄₃). I(tonic) facilitation of a selective GAT-1 blocker (NO-711) was significantly less at P₆₋₈ than after P₁₃₋₁₅. The facilitation of I(tonic) by SNAP-5114, a GAT-3 inhibitor, was negligible in the absence of exogenous GABA at all tested ages. In contrast, I(tonic) in the presence of a nonselective GAT blocker (nipecotic acid, NPA) gradually decreased with age during the preadolescent period, which was mimicked by I(tonic) changes in the presence of exogenous GABA. I(tonic) sensitivity to L-655,708, a GABA(A)R α₅ subunit inverse agonist, gradually decreased during the preadolescent period in the presence of NPA or exogenous GABA. Finally, Western blot analysis showed that the expression of the GABA(A)R α₅ subunit in the dentate gyrus gradually decreased with age. Collectively, our results suggested that the I(tonic) regulation of altered GATs is under the final tune of GABA(A)R α₅ subunit activation in DGGCs at different ages.