Low dose of corticosterone treatment with exercise increases hippocampal cell proliferation, and improves cognition

Intermediate level of stress is beneficial for brain functions, whereas extreme low level or high level of stress is deleterious. We have previously shown that chronic exposure to high doses of corticosterone （CORT） suppressed hippocampal plasticity and physical exercise in terms of running counteracted the detrimental effects of CORT treatment. We aimed to study whether a mild stress, that mimicked by a treatment with low CORT dose, improved hippocampal plasticity in terms of hippocampal cell proliferation and dendritic remodeling, and to examine whether running with CORT treatment showed an additive effect on improving hippocampal plasticity. The rats were treated with 20 mg/kg CORT for 14 days with or without running, followed by Morris water maze test or forced swim test. The hippocampal proliferating cells was labeled by intraperitoneal injection of 5-bromo-2＇-deoxyuridine. The dendritic morphology was analyzed using Golgi staining method. Treatment with 20 mg/kg CORT alone yielded a higher number of hippocampal cell proliferation and significantly increased dendritic branching compared to vehicle-treated non-runners, but had no behavioral effects. In contrast, CORT treatment with running showed an additive increase in hippocampal cell proliferation and dendritic remodeling that was associated with improved spatial learning and decreased depression-like behavior; however, there was no additive improvement in behavior compared to vehicle-treated runners. These findings suggest that mild stress does not always cause detrimental effect on the brain, and combining mild stress with running could promote hippocampal plasticity via inducing cell proliferation and dendritic remodeling.

In vitro differentiation of human adipose-derived adult stromal cells into neuron-like cells in hippocampal astrocyte conditioned medium

BACKGROUND: At present, researches on differentiating from human adipose-derived adult stromal cells (hADASC) to neuron-like cells are focus on inducing by artificial-synthetic compound solution; however, hippocampal astrocyte conditioned medium (HCAM) can induce in vitro differentiation from hADASC to neuron-like cells is still unclear. OBJECTIVE: To observe whether HCAM can induce in vitro differentiation from hADASC to neuron-like cells. DESIGN: Randomized control study. SETTING: Department of Neurology, Taixing People's Hospital; Central Laboratory, North China Coal Medical College. MATERIALS: Donor of adipose tissue was donated by female volunteers suffering from caesarean section in the department of obstetrics & gynecology in our hospital and aged 20-35 years. Adipose tissue was collected from subcutaneous tissue of abdomen during the operation. In addition, 8 male newborn Wistar rats within 24 hours with average body mass of 20 g were provided by Animal Institute of Chinese Academy of Medical Sciences. Rabbit-anti-human Nestin polyclonal antibody, rabbit-anti-human glial fibriliary acidic protein (GFAP) polyclonal antibody, rabbit-anti-human neuro-specific enolase polyclonal antibody and mouse-anti-human microtubal associated protein 2 (MAP-2) polyclonal antibody were provided by Wuhan Boster Company. METHODS: The experiment was carried out in the Central Laboratory of North China Coal Medical College from October 2004 to June 2005. hADASC was cultured with HCAM and its growth and morphological changes were observed under inverted phase contrast microscope. Immunocytochemistry, immunofluorescence and Western blotting were used to evaluate the expressions of Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. MAIN OUTCOME MEASURES: Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. RESULTS: On the 3rd day of culture, partial hADASC started deformation from slender shuttle-shape cells to neuron-like cells. It suggested that cells stretched out apophysis, which were mainly double-pole or multiple-pole cells. Five days later, immunohistochemical detection suggested that expression of Nestin (10.5±0.037) was found out in cells; meanwhile, expressions of GFAP (38.4±0.052) and neuro-specific enolase (NSE) (15.7±0.023) were also found out in cells; however, expression of MAP-2 was not observed. Western blot indicated that, 5 days after effect of HCAM, Nestin was found out in hADASC; meanwhile, expressions of GFAP and neuro-specific enolase were also found out; however, expression of MAP-2 was not observed. CONCLUSION: HCAM can induce the differentiation from hADASC to neuron-like cells in vitro.

Down-regulation of N-methyl-D-aspartate receptor subunits 1 affects neurogenesis of hippocampal neural stem cells

Schizophrenia is a common and serious mental illness characterized by severe impairments in thinking,emotions,and behaviors.Usually,the cognitive deficits of schizophrenia are closely associated with abnormal neurogenesis due to the hypofunction of certain neural receptors such as N-methyl-D-aspartate receptors(NMDARs),which mediates neurotransmission.However,little is known about the involvement of NMDAR1 in regulating hippocampal neurogenesis in schizophrenia.In the current study,we present evidence suggesting that NMDAR1 regulates hippocampal neurogenesis as lentivirus-mediated shRNA silencing NMDAR1 gene or blocking with MK-801 results in abnormal neurogenesis consistently found in schizophrenia.The important finding was clearly demonstrated by the multiparametric assessments,including morphology,immunofluorescence,western blotting,and flow cytometry.Simultaneously,our results indicated that knockdown and blockade of NMDAR1 significantly attenuated the proliferation of hippocampal neural stem cells(hNSCs)and decreased the differentiation to neurons.More importantly,the blockade of NMDAR1 with MK-801 aggravated the apoptosis of hNSCs.Thus,it is likely that NMDAR1 functions as a new target for the treatment of schizophrenia.Our present study may provide a novel insight for further investigation of the pathogenesis of schizophrenia.

Real-time effects of nicotine exposure and withdrawal on neurotransmitter metabolism of hippocampal neuronal cells by microfluidic chip-coupled LC-MS

Nicotine ingested from smoking exerts neuroprotection and developmental neurotoxicity in central nervous system.It can produce several changes of cognitive behaviors through regulating the release of different neurotransmitters in the brain.However,the effects of nicotine exposure or withdrawal on neurotransmitter metabolism of hippocampus are still unclear.In this study,we real-time evaluated the dynamic alterations in neurotransmitter metabolism of hippocampal neuronal(HT22)cells induced by nicotine exposure and withdrawal at relevant exposure levels of smoking and secondhand smoke by using a microfluidic chip-coupled with liquid chromatography-mass spectrometry(MC-LC-MS)system.We found HT22 cells mainly released related neurotransmitters of tryptophan and choline metabolism,both nicotine exposure and withdraw altered its neurotransmitters and their metabolites release.Exposure to nicotine mainly altered the secretion of serotonin,kynurenic acid,choline and acetylcholine of HT22 cells to improve hippocampal dependent cognition,and the change are closely related to the dose and duration of exposure.Moreover,the altered metabolites could rapidly recover after nicotine withdrawal,but picolinic acid was elevated.MC-LC-MS system used in present study showed a greater advantage to detect unstable metabolites than conventional method by using in vitro model,and the results of dynamic alterations of neurotransmitter metabolism induced by nicotine might provide a potential targets for drug development of neuroprotection or cognitive improvement.

Effects of Single and Repeated Exposure to a 50-Hz 2-mT Electromagnetic Field on Primary Cultured Hippocampal Neurons

The prevalence of domestic and industrial electrical appliances has raised concerns about the health risk of extremely low-frequency magnetic fields（ELF-MFs）. At present, the effects of ELF-MFs on the central nervous system are still highly controversial, and few studies have investigated its effects on cultured neurons. Here, we evaluated the biological effects of different patterns of ELF-MF exposure on primary cultured hippocampal neurons in terms of viability, apoptosis, genomic instability,and oxidative stress. The results showed that repeated exposure to 50-Hz 2-mT ELF-MF for 8 h per day after different times in culture decreased the viability and increased the production of intracellular reactive oxidative species in hippocampal neurons. The mechanism was potentially related to the up-regulation of Nox2 expression.Moreover, none of the repeated exposure patterns had significant effects on DNA damage, apoptosis, or autophagy, which suggested that ELF-MF exposure has no severe biological consequences in cultured hippocampal neurons.