Hippocampal Cell Viability Research Articles

Histopathological, immunohistochemical, and stereological analysis of the effect of Ginkgo biloba (Egb761) on the hippocampus of rats exposed to long-term cellphone radiation.

Cellular phones are major sources of electromagnetic radiation (EMR) that can penetrate the human body and pose serious health hazards. The increasingly widespread use of mobile communication systems has raised concerns about the effects of cellphone radiofrequency (RF) on the hippocampus because of its close proximity to radiation during cellphone use. The effects of cellphone EMR exposure on the hippocampus of rats and the possible counteractive effects of Ginkgo biloba (Egb761) were aimed to investigate. Rats were divided into three groups: Control, EMR, and EMR+Egb761. The EMR and EMR+Egb761 groups were exposed to cellphone EMR for one month. Egb761 was also administered to the EMR+Egb761 group. Specifically, we evaluated the effect of RF exposure on rat hippocampi at harmful EMR levels (0.96 W/kg specific absorption rate [SAR]) for one month and also investigated the possible impact of Ginkgo biloba (Egb761) using stereological, TUNEL-staining, and immunohistochemical methods. An increase in apoptotic proteins (Bax, Acas-3) and a decrease in anti-apoptotic protein (Bcl-2) immunoreactivity along with a decrease in the total granule and pyramidal cell count were noted in the EMR group. A decrease in Bax and Acas-3 and an increase in Bcl-2 immunoreactivity were observed in rats treated with Egb761 in addition to a decrease in TUNEL-stained apoptotic cells and a higher total viable cell number. In conclusion, chronic cellphone EMR exposure may affect hippocampal cell viability, and Egb761 may be used to mitigate some of the deleterious effects.

Indirubin derivatives protect against endoplasmic reticulum stress-induced cytotoxicity and down-regulate CHOP levels in HT22 cells

Indirubin and its derivatives have been reported to exhibit anti-cancer and anti-inflammatory activities. Recently, some of its derived analogs have been shown to have neuroprotective potential. Endoplasmic reticulum (ER) stress has been demonstrated to contribute to the pathogenesis of various neurodegenerative diseases, whereas the effects of indirubin derivatives on ER stress-induced cell death have not been addressed. In the present study, a series of 44 derivatives of indirubin was prepared to search for a novel class of neuroprotective agents against ER stress-induced neuronal death. The MTT reduction assay indicated that tunicamycin (TM), an inducer of ER stress, significantly decreased the viability of hippocampal neuronal HT22 cells. Among the compounds tested, eight showed significant inhibitory activity against TM-induced cell death. Western blot analysis showed that application of these analogs to the cells simultaneously with TM reduced the TM-induced expression of CHOP, an established mediator of ER stress. Our results suggest that the preventive effect of these indirubin derivatives against ER stress-induced neuronal death may be due, at least in part, to attenuation of the CHOP-dependent signaling system.

Biocompatibility of very small superparamagnetic iron oxide nanoparticles in murine organotypic hippocampal slice cultures and the role of microglia.

Superparamagnetic iron oxide nanoparticles (SPIO) are applied as contrast media for magnetic resonance imaging (MRI) and treatment of neurologic diseases despite the fact that important information concerning their local interactions is still lacking. Due to their small size, SPIO have great potential for magnetically labeling different cell populations, facilitating their MRI tracking in vivo. Before SPIO are applied, however, their effect on cell viability and tissue homoeostasis should be studied thoroughly. We have previously published data showing how citrate-coated very small superparamagnetic iron oxide particles (VSOP) affect primary microglia and neuron cell cultures as well as neuron-glia cocultures. To extend our knowledge of VSOP interactions on the three-dimensional multicellular level, we further examined the influence of two types of coated VSOP (R1 and R2) on murine organotypic hippocampal slice cultures. Our data show that 1) VSOP can penetrate deep tissue layers, 2) long-term VSOP-R2 treatment alters cell viability within the dentate gyrus, 3) during short-term incubation VSOP-R1 and VSOP-R2 comparably modify hippocampal cell viability, 4) VSOP treatment does not affect cytokine homeostasis, 5) microglial depletion decreases VSOP uptake, and 6) microglial depletion plus VSOP treatment increases hippocampal cell death during short-term incubation. These results are in line with our previous findings in cell coculture experiments regarding microglial protection of neurite branching. Thus, we have not only clarified the interaction between VSOP, slice culture, and microglia to a degree but also demonstrated that our model is a promising approach for screening nanoparticles to exclude potential cytotoxic effects.

Comments on Bozzatello et al. Supplementation with Omega-3 Fatty Acids in Psychiatric Disorders: A Review of Literature Data. J. Clin. Med. 2016, 5, 67.

Paola Bozzatello et al. [1] have done a comprehensive qualitative review of the potential use of long-chain polyunsaturated fatty acids in the prevention and treatment of mental disorders.[...].

Effect of Cyclosporin A on the Viability of Hippocampal Cells Cultured under Conditions of Modeling of Alzheimer’s Disease

The presence of amyloid plaques and neurofibrillary tangles accompanied by manifestations of intense neurodegeneration in the brain is the main syndrome of Alzheimer’s disease (AD). Until now, the mechanisms underlying neurotoxic properties of the protein specific with respect to AD (amyloid β1–42) have not been fully interpreted. There are reasons to believe that the opening of mitochondrial permeability transition pores (MPTPs) may play a significant role in the respective processes. We estimated the impact of the mentioned protein on the viability of cultured hippocampal cells of rats. The use of confocal microscopy after staining of the cells by two dyes, Hoechst 33258 and propidium iodide, allowed us to measure the numbers of viable and necrotized units. When 2.0 μm of amyloid β1–42 was added to the culturing medium, the cell death index (CDI) of hippocampal cells (number of cells stained by propidium iodide normalized with respect to the number of examined units) on day in vitro (DIV) 14 was 59 ± 4%, on average, as compared with 28 ± 6% under control conditions. When not only amyloid β1–42 was added to the medium but cells were also treated with 1.25 μM of a MPTP blocker, cyclosporin A (CsA), the mean CDI was significantly smaller than that with no treatment (42 ± 6%; P < 0.05). Thus, changes in the mitochondria resulting in opening of MPTPs can be considerably involved in the process of necrotic death of hippocampal cells under conditions of modeling of AD.

Neurobehavioral assessment following e-cigarette refill liquid exposure in adult rats

The present study was conducted to assess the toxic effect of e-cigarette refill liquid on cognitive and motor functions in adult rats. Animals were administered 28 μl/kg of body weight of e-liquid with/without a dose of 0.5 mg of nicotine/kg of body weight, using the intraperitoneally route for a period of 4 weeks. They were then evaluated by novel object recognition test (NORT) and spontaneous alternation T-maze test for cognitive functions. Results indicated that e-liquid without nicotine induced, in the NORT, a decrease in time exploring the novel object during the test session and lower discrimination and recognition indexes compared to control and e-liquid with nicotine treated rats. Furthermore, short-term spatial memory was affected after e-liquid treatment in the spontaneous alternation T-maze test, identifying recognition memory impairments. However, none of the treatments altered motor functions assessed by inclined plane test, Kondziela’s inverted screen test and weights test. Cell cytotoxicity assessment following e-liquid exposure showed a significant decrease in hippocampal cell viability, but no change in cortical cell viability. Thereby, e-liquid without nicotine causes cognitive impairments, especially on the hippocampus. Based on these results, more extensive assessments on e-cigarettes must be carried out.

Propofol protects hippocampal neurons from apoptosis in ischemic brain injury by increasing GLT-1 expression and inhibiting the activation of NMDAR via the JNK/Akt signaling pathway.

Ischemic brain injury(IBI) can cause nerve injury and is a leading cause of morbidity and mortality worldwide. The neuroprotective effects of propofol against IBI have been previously demonstrated. However, the neuroprotective effects of propofol on hippocampal neurons are not yet entirely clear. In the present study, models of IBI were established in hypoxia-exposed hippocampal neuronal cells. Cell viability assay and apoptosis assay were performed to examine the neuroprotective effects of propofol on hippocampal neurons in IBI. A significant decrease in cell viability and a significant increase in cell apoptosis were observed in the IBI group compared with the control group, accompanied by a decrease in glial glutamate transporter-1(GLT‑1) expression as determined by RT-qPCR and western blot analysis. The effects of IBI were reversed by propofol treatment. The siRNA-mediated knockdown of GLT‑1 in the hypoxia-exposed hippocampal neuronal cells led to an increase in cell apoptosis, JunN-terminal kinase(JNK) activation and N-methyl-D‑aspartate(NMDA) receptor(NR1 and NR2B) activation, as well as to a decrease in cell viability and a decrease in Akt activation. The effects of RNA interference-mediated GLT‑1 gene silencing on cell viability, JNK activation, NMDAR activation, cell apoptosis and Akt activation in the hippocampal neuronal cells were slightly reversed by propofol treatment. The JNK agonist, anisomycin, and the Akt inhibitor, LY294002, both significantly blocked the effects of propofol on hippocampal neuronal cell viability and apoptosis in IBI. The decrease in JNK activation and the increase in Akt activation caused by GLT‑1 overexpression were reversed by NMDA. Collectively, our findings suggest that propofol treatment protects hippocampal neurons against IBI by enhancing GLT‑1 expression and inhibiting the activation of NMDAR via the JNK/Akt signaling pathway.

Dehydroepiandrosterone protects male and female hippocampal neurons and neuroblastoma cells from glucose deprivation

Dehydroepiandrosterone (DHEA) modulates neurogenesis, neuronal function, neuronal survival and metabolism, enhancing mitochondrial oxidative capacity. Glucose deprivation and hypometabolism have been implicated in the mechanisms that mediate neuronal damage in neurological disorders, and some studies have shown that these mechanisms are sexually dimorphic. It was also demonstrated that DHEA is able to attenuate the hypometabolism that is related to some neurodegenerative diseases, eliciting neuroprotective effects in different experimental models of neurodegeneration. The aim of this study was to evaluate the effect of DHEA on the viability of male and female hippocampal neurons and SH-SY5Y neuroblastoma cells exposed to glucose deprivation. It was observed that after 12h of pre-treatment, DHEA was able to protect SH-SY5Y cells from glucose deprivation for 6h (DHEA 10−12, 10−8 and 10−6M) and 8h (DHEA 10−8M). In contrast, DHEA was not neuroprotective against glucose deprivation for 12 or 24h. DHEA (10−8M) also protected SH-SY5Y cells when added together or even 1h after the beginning of glucose deprivation (6h). Furthermore, DHEA (10−8M) also protected primary neurons from both sexes against glucose deprivation. In summary, our findings indicate that DHEA is neuroprotective against glucose deprivation in human neuroblastoma cells and in male and female mouse hippocampal neurons. These results suggest that DHEA could be a promising candidate to be used in clinical studies aiming to reduce neuronal damage in people from both sexes.

Chronic Psychosocial Stress and Negative Feedback Inhibition: Enhanced Hippocampal Glucocorticoid Signaling despite Lower Cytoplasmic GR Expression.

Chronic subordinate colony housing (CSC), a pre-clinically validated mouse model for chronic psychosocial stress, results in increased basal and acute stress-induced plasma adrenocorticotropic hormone (ACTH) levels. We assessed CSC effects on hippocampal glucocorticoid (GC) receptor (GR), mineralocorticoid receptor (MR), and FK506 binding protein (FKBP51) expression, acute heterotypic stressor-induced GR translocation, as well as GC effects on gene expression and cell viability in isolated hippocampal cells. CSC mice showed decreased GR mRNA and cytoplasmic protein levels compared with single-housed control (SHC) mice. Basal and acute stress-induced nuclear GR protein expression were comparable between CSC and SHC mice, as were MR and FKBP51 mRNA and/or cytoplasmic protein levels. In vitro the effect of corticosterone (CORT) on hippocampal cell viability and gene transcription was more pronounced in CSC versus SHC mice. In summary, CSC mice show an, if at all, increased hippocampal GC signaling capacity despite lower cytoplasmic GR protein expression, making negative feedback deficits in the hippocampus unlikely to contribute to the increased ACTH drive following CSC.

Glutamate levels control HT22 murine hippocampal cell death by regulating biphasic patterns of Erk1/2 activation: role of metabolic glutamate receptor 5.

Extracellular glutamate concentration is a critical determinant of neuronal cell fate. We recently demonstrated that HT22 murine hippocampal cell viability was reduced by exposure to high concentrations of glutamate, whereas low concentrations promoted cell survival. Extracellular signal-regulated kinase (Erk)1/2 activation by glutamate is important for both glutamate-induced cell death and survival. In this study, we investigated the role of glutamate-induced or hydrogen peroxide (H2O2)-induced Erk1/2 activation in HT22 cell fate determination. Glutamate and H2O2 treatment similarly induced early (<1 h) Erk1/2 phosphorylation regardless of concentration. On the other hand, persistent Erk1/2 phosphorylation (16-24 h) was observed only in the presence of excess glutamate. Only the latter contributed to glutamate-induced cell death, which involved metabolic glutamate receptor 5. Our findings suggest that glutamate concentration modulates two distinct phases of Erk1/2 activation, which can explain the glutamate concentration-dependent determination of HT22 cell fate.

Fermentation enhances the neuroprotective effect of shogaol-enriched ginger extract via an increase in 6-paradol content

This study was designed to investigate the neuroprotective effect of fermented shogaol-enriched extract (FSE), which is converted to 6-paradol by Aspergillus niger. FSE was fermented for varying time points (FSE-0, FSE-30, and FSE-60). Optimal condition for 6-paradol produced by A. niger was determined as initial inoculated cell concentration (1.5 × 106 spores/mL) from shogaol-enriched extract (240 µg/mL) for 60 h. The ability of FSE to protect the rat primary hippocampal cells from beta-amyloid (Αβ) oligomer and Αβ plaque induced neurotoxicity and to inhibit acetylcholinesterase (AChE) activity was evaluated. Hippocampal cell viability was reduced to 70% when exposed to Αβ oligomer, and exposure to Αβ plaque for 18 h and 50 µg/mL of FSE-60 increased cell viability (92% and 95.3%, respectively). In addition AChE inhibitory activity of FSE-60 at 50 µg/mL was 53%, which was similar to 0.1 µM tacrine. Therefore, these results demonstrate that FSE-60 has potential as a neuroprotective agent.

Prophylactic combined supplementation of choline and docosahexaenoic acid attenuates vascular cognitive impairment and preserves hippocampal cell viability in rat model of chronic cerebral hypoperfusion ischemic brain injury

Background: Stroke is the second cause of mortality in the world and third leading cause of disability in surviving victims. Cerebral ischemic cascade involves multiple pathways that can result in motor and cognitive deficits. The current treatment strategy focuses mainly on motor recovery, and the management of post-stroke cognitive impairment is largely neglected. Similarly, very few studies have explored the prophylactic combined synergetic treatment strategies that have the potential to target multiple pathways in the ischemic cascade to alleviate vascular cognitive impairment (VCI) in the event of an ischemic stroke. Choline and docosahexaenoic acid (Cho-DHA) are both essential neuronal membrane phospholipid precursors, known to be important in enhancing cognitive functions. The objective of present study was to explore the prophylactic efficacy of combined Cho-DHA supplementation (Cho-DHA suppl.) in attenuating VCI in a rodent model of ischemic brain injury. Methods: An 10-months-old male Wistar rats were subdivided into four groups (n=8/group); normal control (NC), bilateral common carotid artery occlusion (BCCAO) induced ischemic brain injury group, sham BCCAO (S-BCCAO) group, and prophylactic combined Cho-DHA suppl. BCCAO group. Subsequently, all groups of rats were tested for cognition and neuro-morphological changes in the hippocampus. Results: BCCAO rats showed significant learning and memory deficits (p<0.05) and neuronal injury compared to S-BCCAO and NC rats. These cognitive deficits and neuronal injury were significantly (p<0.01) attenuated in Cho-DHA suppl. BCCAO rats. Conclusion: Prophylactic combined Cho-DHA suppl. may be envisaged as an effective preventive strategy to attenuate VCI and neuronal injury in high-risk individuals susceptible for a future event of an ischemic stroke.

Acetylpuerarin increases cell viability and reduces apoptosis in rat hippocampal neurons following oxygen-glucose deprivation/reperfusion

The effects of acetylpuerarin treatment following oxygen-glucose deprivation/reperfusion (OGD/R) were examined in rat hippocampal neurons in vitro and compared with the effects of acetylpuerarin in normoxic cells to confirm acetylpuerarin's potential neuroprotective effects, including apoptosis inhibition. Wistar rat embryo hippocampal cells (day 18, E18) cultured for 8 days were subjected to 3 h OGD treatment, followed by reperfusion for 12, 24 or 36 h. For each time interval, a group of cells was left untreated (OGD/R-only groups) and treated with 0.1, 0.4 and 1.6 µM acetylpuerarin (OGD/R+acetylpuerarin). Neuron viability, apoptosis and caspase-8 and -3 activities were assessed by the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 4',6-diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL) and spectrophotometric assays, respectively. Fas-ligand (Fas-L), Fas-associated death domain (FADD) and tumor necrosis factor-α (TNF-α) were determined by western blot analysis. Compared with control cells, OCD/R+acetylpuerarin cells treated with 0.1, 0.4 and 1.6 µM doses showed a concentration-dependent increase in hippocampal cell survival and viability by 69.93 ± 2.28%, 81.49 ± 2.13% and 85.28 ± 2.38% at 12 h, 68.59 ± 3.02%, 77.85 ± 2.84% and 85.64 ± 4.39% at 24 h and 69.70 ± 1.70%, 77.21 ± 3.21% and 83.90 ± 2.12% at 36 h (P<0.05). Furthermore, OCD/R+acetylpuerarin cells exhibited a dose-dependent decrease in caspase-8 and -3 activation, TUNEL and DAPI-positive neurons and Fas-L, FADD and TNF-α expression. In conclusion, acetylpuerarin protects against OGD/R-induced neuronal apoptosis predominantly in the first 24 h following ischemia, which may be useful in mediating neuronal apoptosis in ischemic stroke patients.

Nelfinavir Inhibits Intra-Mitochondrial Calcium Influx and Protects Brain against Hypoxic-Ischemic Injury in Neonatal Mice

Nelfinavir (NLF), an antiretroviral agent, preserves mitochondrial membranes integrity and protects mature brain against ischemic injury in rodents. Our study demonstrates that in neonatal mice NLF significantly limits mitochondrial calcium influx, the event associated with protection of the brain against hypoxic-ischemic insult (HI). Compared to the vehicle-treated mice, cerebral mitochondria from NLF-treated mice exhibited a significantly greater tolerance to the Ca2+-induced membrane permeabilization, greater ADP-phosphorylating activity and reduced cytochrome C release during reperfusion. Pre-treatment with NLF or Ruthenium red (RuR) significantly improved viability of murine hippocampal HT-22 cells, reduced Ca2+ content and preserved membrane potential (Ψm) in mitochondria following oxygen-glucose deprivation (OGD). Following histamine-stimulated Ca2+ release from endoplasmic reticulum, in contrast to the vehicle-treated cells, the cells treated with NLF or RuR also demonstrated reduced Ca2+ content in their mitochondria, the event associated with preserved Ψm. Because RuR inhibits mitochondrial Ca2+ uniporter, we tested whether the NLF acts via the mechanism similar to the RuR. However, in contrast to the RuR, in the experiment with direct interaction of these agents with mitochondria isolated from naïve mice, the NLF did not alter mitochondrial Ca2+ influx, and did not prevent Ca2+ induced collapse of the Ψm. These data strongly argues against interaction of NLF and mitochondrial Ca2+ uniporter. Although the exact mechanism remains unclear, our study is the first to show that NLF inhibits intramitochondrial Ca2+ flux and protects developing brain against HI-reperfusion injury. This novel action of NLF has important clinical implication, because it targets a fundamental mechanism of post-ischemic cell death: intramitochondrial Ca2+ overload → mitochondrial membrane permeabilization → secondary energy failure.

Are newborn rat-derived neural stem cells more sensitive to lead neurotoxicity?

Lead ion (Pb2+) has been proven to be a neurotoxin due to its neurotoxicity on mammalian nervous system, especially for the developing brains of juveniles. However, many reported studies involved the negative effects of Pb2+ on adult neural cells of humans or other mammals, only few of which have examined the effects of Pb2+ on neural stem cells. The purpose of this study was to reveal the biological effects of Pb2+ from lead acetate [Pb (CH3COO)2] on viability, proliferation and differentiation of neural stem cells derived from the hippocampus of newborn rats aged 7 days and adult rats aged 90 days, respectively. This study was carried out in three parts. In the first part, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT viability assay) was used to detect the effects of Pb2+ on the cell viability of passage 2 hippocampal neural stem cells after 48-hour exposure to 0–200 μM Pb2+. In the second part, 10 μM bromodeoxyuridine was added into the culture medium of passage 2 hippocampal neural stem cells after 48-hour exposure to 0–200 μM Pb2+, followed by immunocytochemical staining with anti-bromodeoxyuridine to demonstrate the effects of Pb2+ on cell proliferation. In the last part, passage 2 hippocampal neural stem cells were allowed to grow in the differentiation medium with 0–200 μM Pb2+. Immunocytochemical staining with anti-microtubule-associated protein 2 (a neuron marker), anti-glial fibrillary acidic protein (an astrocyte marker), and anti-RIP (an oligodendrocyte marker) was performed to detect the differentiation commitment of affected neural stem cells after 6 days. The data showed that Pb2+ inhibited not only the viability and proliferation of rat hippocampal neural stem cells, but also their neuronal and oligodendrocyte differentiation in vitro. Moreover, increased activity of astrocyte differentiation of hippocampal neural stem cells from both newborn and adult rats was observed after exposure to high concentration of lead ion in vitro. These findings suggest that hippocampal neural stem cells of newborn rats were more sensitive than those from adult rats to Pb2+ cytotoxicity.

&lt;em&gt;Acalypha indica&lt;/em&gt; Linn root extract improved hippocampal cell viability and increased brain-derived neurotrophic factor (BDNF) in hypoxic condition

Background: This study was done to determine the effect of root extract of Acalypha indica Linn (akar kucing) in protecting neuron viability of the rat hippocampus on tissue culture in hypoxic condition. Methods: This is an experimental study of in vitro primary cell culture of hippocampus of Sprague Dowley adult rat. The cultures were group into control (C) and exposure to root extract of Acalypha indica Linn with dose of 10 mg/mL, 15 mg/mL, and 20 mg/mL for 72 hours. The cultures were then exposed to hypoxic gas (5% oxygen, 5% carbondioxide, nitrogen balance) for 24 hours. After that, relative cell viability was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), cell proliferation by 5-bromo2’-deoxy-uridine (BrdU), and Brain-derived Neurotrophic Factor (BDNF) levels by BDNF ELISA kit. Results: The result showed MTT viability (C: 99.7%, A indica L 10: 326.3%, A indica L 15: 411.7%, A indica L 20: 445.9%), BrdU absorbance (C: 0.07, A indica L 10: 0.10, A indica L 15: 0.12, A indica L 20: 0.13) of the exposured hippocampal cell were significantly higher than the control group (p &lt; 0.01) accompany by increased level of BDNF (C: 11.3 pg/mL, A indica L 10: 12.5 pg/mL, A indica L 15: 23.1 pg/mL, A indica L 20: 18.1 pg/mL). Conclusion: The root extract of Acalypha indica Linn is able to improve rat hippocampal cell viability and endogenous BDNF levels in hypoxic condition. (Med J Indones. 2012;21:141-6)

Endoplasmic reticulum stress contributes to CRH-induced hippocampal neuron apoptosis

The hypothalamic–pituitary–adrenal (HPA) axis is critical to mediating the body's response to stress. Corticotropin releasing hormone (CRH) plays a central role in controlling the stress response and regulating the HPA axis. Recent findings support CRH participates in the stress-induced hippocampal neuron apoptosis, but the underlying mechanisms are not fully understood. Our present study demonstrates that CRH can independently decrease hippocampal neuron cell viability in vitro in a concentration- and time-dependent manner. CRH receptor 1 (CRHR1) is involved in CRH-induced neuron apoptosis. Endoplasmic reticulum (ER) stress response marker, glucose-regulated protein 78 (GRP78), either protein or mRNA, is significantly elevated after treatment of CRH, and decreased when co-treated with salubrinal, ER stress inhibitor. The ER stress associated proapoptotic transcription factor C/EBP homologous protein (CHOP) and cleavage of caspase-12 protein expression are also increased following CRH treatment. Furthermore, we investigate which ER stress cascades are affected by CRH. CRH activates inositol-requiring enzyme 1 (IRE1), apoptosis signal regulating kinase 1 (ASK1), and c-jun kinase (JNK). Neuron apoptotic rate, examined by flow cytometry, is increased when CRH treatment and attenuated by salubrinal, thioredoxin (ASK1 inhibitor) and SP600125 (JNK inhibitor). Therefore, current data indicate that ER stress, through activating the IRE1/ASK1/JNK cascade, plays an important role in CRH-induced neuron apoptosis.

Genistein and daidzein promote cell proliferation and neurotrophin expression in hippocampal H19-7 cell line

Objective To determine the effects of genistein and daidzein on the proliferation and survival of the hippocampal neural cells and underlying mechanism. Methods H19-7/IGF-IR neural cell line was cultured in phenol red free DMEM absented of serum for 72h. Genistein, daidzein or 17β-estradiol was added to the culture at various concentrations. Their proliferation and protective effects on the neuronal cells were determined by BrdU and MTT assay respectively. The effect of phytoestrogens on cell cycle regulation was determined using flow cytometry. The effects of the soy isoflavones on brain-derived neurotrophic factor (BDNF) expression were determined by ELISA and RT-PCR respectively. Results It was observed that, with 72h of treatment, 20nM and 200 nM 17B-estradiol significantly promoted the neuronal cell proliferation at 33% and 36% ;20nM and 200nM genistein significantly promoted the neuronal cell proliferation at 15% and 13% ; 200nM daidzein significantly promoted the neuronal cell proliferation at 11% compared to the control (P＜0.05). Genistein and daidzein induced an significantly increase in the S phase arrest at (17.64 ± 0.43) % and (19.48 ± 1.01) % compared to the control (P ＜ 0. 05). Moreover, genistein and daidzein significantly increased the expression of mature BDNF and BDNF mRNA level (P＜0.05). The effect of genistein and daidzein on hippocampal neuronal cell proliferation was blocked by K252a, selective inhibitor of tyrosine kinase receptors. Conclusion Genistein and daidzein improved hippocampal neuronal cell proliferation and viability in vitro. The effects might be mediated by increasing in BDNF expression. Key words: Genistein; Daidzein; Hippocampus; Brain-derived neurotrophic factor; Proliferation

Clinically Relevant Progestins Regulate Neurogenic and Neuroprotective Responses in Vitro and in Vivo

Previously, we demonstrated that progesterone (P(4)) promoted adult rat neural progenitor cell (rNPC) proliferation with concomitant regulation of cell-cycle gene expression via the P(4) receptor membrane component/ERK pathway. Here, we report the efficacy of seven clinically relevant progestins alone or in combination with 17β-estradiol (E(2)) on adult rNPC proliferation and hippocampal cell viability in vitro and in vivo. In vitro analyses indicated that P(4), norgestimate, Nestorone, norethynodrel, norethindrone, and levonorgestrel (LNG) significantly increased in rNPC proliferation, whereas norethindrone acetate was without effect, and medroxyprogesterone acetate (MPA) inhibited rNPC proliferation. Proliferative progestins in vitro were also neuroprotective. Acute in vivo exposure to P(4) and Nestorone significantly increased proliferating cell nuclear antigen and cell division cycle 2 expression and total number of hippocampal 5-bromo-2-deoxyuridine (BrdU)-positive cells, whereas LNG and MPA were without effect. Mechanistically, neurogenic progestins required activation of MAPK to promote proliferation. P(4), Nestorone, and LNG significantly increased ATP synthase subunit α (complex V, subunit α) expression, whereas MPA was without effect. In combination with E(2), P(4), Nestorone, LNG, and MPA significantly increased BrdU incorporation. However, BrdU incorporation induced by E(2) plus LNG or MPA was paralleled by a significant increase in apoptosis. A rise in Bax/Bcl-2 ratio paralleled apoptosis induced by LNG and MPA. With the exception of P(4), clinical progestins antagonized E(2)-induced rise in complex V, subunit α. These preclinical translational findings indicate that the neurogenic response to clinical progestins varies dramatically. Progestin impact on the regenerative capacity of the brain has clinical implications for contraceptive and hormone therapy formulations prescribed for pre- and postmenopausal women.

The novel radical scavenger IAC is effective in preventing and protecting against post-ischemic brain damage in Mongolian gerbils

The removal of pathologically generated free radicals produced during ischemia, reperfusion and intracranical hemorrhage seems to be a viable approach to neuroprotection. However, at present, no neuroprotective agent has proven effective in focal ischemic stroke phase III trials, despite the encouraging data in animal models. This study aimed to explore the effect of the brain penetrant low molecular weight radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate (IAC) in neurological damage subsequent to ischemia–reperfusion injury in Mongolian gerbils. We examined the intraperitoneal effects of IAC on temporary bilateral common carotid artery occlusion (BCCO) by means of morphological and histological analysis of the hippocampus. Significant dose-dependent protective effects of IAC (1 to 10 mg/kg b.w.) against neuropathological and morphological brain changes were seen when administered i.p. 1 h before temporary BCCO in Mongolian gerbils. When administered up to 6 h after BCCO, IAC actually reverses the neurodegenerative processes (e.g. hippocampal cell viability) induced by ischemia in a dose-dependent fashion. Data show that IAC is highly effective in protecting and preventing oxidative brain damage associated with cerebral flow disturbances. It is also effective even in late treatment of the insult, emphasizing its potential role for the management of ischemic stroke patients.