Structural elucidation of a non-starch polysaccharides from Lilii Bulbus and its protective effects against corticosterone-induced neurotoxicity in PC12 cells.

Lilii Bulbus is a folk medicine for both culinary and medicinal purpose. In traditional medicine theory, Lilii Bulbus is usually used as an complementary therapy for nourishing the heart and lung, clearing heat in the treatment of mental instability and depression. In this study, NLPS-1a (Mw = 2610 Da, DP = 16), a water-soluble non-starch Lilii Bulbus polysaccharides, was isolated and purified. Structural analysis showed that NLPS-1a mainly contained Man and Glc with a molar ratio of 11.137 and 9.427. The glycosidic linkages of NLPS-1a were 1,3-Manp (59.93%), 1,2-Glcp (37.93%), T-Glcp (1.21%) and T-Manp (0.93%), indicating the highly-linear structures. In addition, NLPS-1a could significantly repair the injury of PC12 cells induced by corticosterone (CORT), reduce Lactate dehydrogenase (LDH) leakage and decrease the cell apoptosis in a dose-dependent manner. Above all, the results indicated that NLPS-1a had protective effects against CORT-induced neurotoxicity in PC12 cells, and might be a natural antidepressant, which enriched the study of the metabolic mechanism between herbal polysaccharides and antidepressant.

Liquiritin protects PC12 cells from corticosterone-induced neurotoxicity via regulation of metabolic disorders, attenuation ERK1/2-NF-κB pathway, activation Nrf2-Keap1 pathway, and inhibition mitochondrial apoptosis pathway.

Liquiritin, a flavone derived from the medicine food homology plant liquorice, possesses neuroprotective. However, the neuroprotective mechanism is not clear. In this study, metabolomics based LC-MS was performed to discover the metabolite changes in PC12 cells treated with corticosterone-induced neurotoxicity after liquiritin treatment. A total of 30 metabolites were identified as differential metabolites. Among them, 11 metabolites were regulated by liquiritin, and involved in the D-glutamine and D-glutamate metabolism, and glutathione metabolism, etc. Based on the results of metabolomics, three cell signaling pathways related to these metabolic pathways were verified. The results showed that the ERK1/2-NF-κB pathway related to the D-glutamine and D-glutamate metabolism was attenuated by liquiritin via down-regulation phospho-ERK1/2, phospho-IκBα, phospho-NF-κB protein expression levels. Furthermore, the Nrf2-Keap1 pathway related to glutathione metabolism was activated by liquiritin via up-regulation Nrf2, Keap1, HO-1, NQO1 protein expression levels, and increased SOD, CAT, GSH-PX enzyme activity, thus exerting antioxidant activity. Additionally, liquiritin inhibited the mitochondrial apoptosis by decreasing the Ca2+ concentration, improving MMP, up-regulating Bcl-2, and down-regulating Bax, cytochrome C, cleaved-Caspase-3 expression levels. These results suggest that the neuroprotective mechanisms of liquiritin are connected to the regulation of metabolic disorders, activation Nrf2/Keap1 pathway, attenuation ERK1/2/NF-κB pathway, and inhibition mitochondrial apoptosis pathway.

Erxian decoction, a famous Chinese medicine formula, antagonizes corticosterone-induced injury in PC12 cells, and improves depression-like behaviours in mice.

Context: In folk medicine, erxian decoction (EXD) is used to treat perimenopausal syndrome in women. It is also used clinically to treat depression, but the mechanism remains unknown.Objectives: To investigate the neuroprotective effect of EXD, and its antidepressant potential.Materials and methods: ICR mice were treated with EXD (0.5, 1.5 and 4.5 g/kg i.g.) and fluoxetine (6.0 mg/kg i.g.) for 10 days. On day 10 of the treatment, depression-like behaviour was induced by reserpine (2.5 mg/kg injected i.p.), and after 24 h of reserpine administration, it was assessed using the tail suspension and forced swimming tests. MTT assay, lactate dehydrogenase test, flow cytometry analysis, Hoechst staining and western blotting were used to assess the apoptosis of PC12 cells. Apoptosis proteins and neurotransmitter were tested in vitro and in vivo, respectively.Results: MTT assay results showed corticosterone prevented cell growth, but EXD at concentrations of 100, 200 and 400 µg/mL restored cell viability (EC50: 204.016 µg/mL). EXD decreased lactate dehydrogenase leakage from 63.48 to 43.60 U/L, and upregulated expression of Bcl-2 while the expression of Bax, caspase-3 and caspase-8 were decreased in vivo and in vitro. Moreover, EXD improved depression-like behaviour in mice, and 4.5 g/kg EXD treatment increased the secretion of serotonin, dopamine and norepinephrine by 67.44, 28.12 and 42.12 pg/mg, respectively, in hypothalamus compared to that of reserpine group.Discussion and conclusions: EXD demonstrated neuroprotective effects and improved depression-like behaviour in mice. Further research should be focussed on the mechanism of the active components in EXD.

Safety evaluation and protective effects of ethanolic extract from maca (Lepidium meyenii Walp.) against corticosterone and H2O2 induced neurotoxicity.

Maca has been traditionally used to enhance sexual behavior and fertility. Recently, maca's neuroprotective effects have been reported. The purpose of this study was to investigate whether the ethanol extract of maca (EEM) (100 mg/kg/bw, 200 mg/kg/bw, 400 mg/kg/bw, p.o.) exerted neuroprotective effects in corticosterone (CORT)-induced (40 mg/kg/bw, s.c.) rats, to determine the neuroprotective effects of EEM (12.5, 25, 50 µg/ml) and macamides in H2O2-induced (50 µM) PC12 cells. The acute toxicity (2000 mg/kg/bw, p.o.) and subacute toxicity (200 mg/kg/bw, 500 mg/kg/bw, 1000 mg/kg/bw, p.o.) of EEM were evaluated by mouse models. EEM reversed CORT-induced abnormal behaviors, reduced the contents of TNF-α, IL-6 in hippocampi, and increased the positive cells of doublecortin (DCX), bromodeoxyuridine (BrdU) and DCX + BrdU in the hippocampus of rats. Moreover, EEM and 4 macamides remarkably increased the cell viability in H2O2-induced PC12 cells. EEM promoted the phosphorylation of IκBα and p65, suppressed the NF-κB activation, and inhibited the levels of pro-inflammatory cytokines such as TNF-α, IL-6 and their mRNA levels in H2O2-induced PC12 cells. In conclusion, EEM could exert neuroprotective effects in CORT-induced rats and in H2O2-induced PC12 cells. Moreover, EEM did not present relevant toxicity after exposure to single and repeated doses.

Corticosterone induces neurotoxicity in PC12 cells via disrupting autophagy flux mediated by AMPK/mTOR signaling.

AIMS: Our previous study indicated that chronic stress caused autophagy impairment and subsequent neuron apoptosis in hippocampus. However, the mechanism underlying the stress-induced damage to neurons is unclear. In present work, we investigated whether stress-level glucocorticoids (GCs) GCs promoted PC12 cell damage via AMPK/mTOR signaling-mediated autophagy. METHODS: Chronic stress-induced PC12 cell injury model was built by treatment with high level corticosterone (CORT). Cell injury was evaluated by flow cytometry assay and transmission electron microscopy observation. RESULTS: Autophagy flux was measured based on the changes in LC3-II and P62 protein expressions, and the color alteration of mCherry-GFP-LC3-II transfection. Our results showed that CORT not only increased cell injury and apoptosis, but also dysregulated AMPK/mTOR signaling-mediated autophagy flux, as indicated by the upregulated expression of LC3-II and P62 proteins, and the lowered ration of autolysosomes to autophagosomes. Mechanistically, our results demonstrated that autophagy activation by AMPK activator metformin or mTOR inhibitor rapamycin obviously promotes cell survival and autophagy flux, improved mitochondrial ultrastructure, and reduced expression of Cyt-C and caspase-3 in CORT-induced PC12 cells. CONCLUSION: These results indicate that high CORT triggers PC12 cell damage through disrupting AMPK/mTOR-mediated autophagy flux. Targeting this signaling may be a promising approach to protect against high CORT and chronic stress-induced neuronal impairment.

Chlorogenic acid protects PC12 cells against corticosterone-induced neurotoxicity related to inhibition of autophagy and apoptosis.

BACKGROUND: There are evidences that chlorogenic acid (CGA) has antidepressant effects, however the underlying molecular mechanism has not been well understood. The aim of the study was to explore the neuroprotective effect of CGA on corticosterone (CORT)-induced PC 12 cells and its mechanism, especially the autophagy pathway. METHODS: PC12 cells were incubated with CORT (0, 100, 200, 400 or 800 µM) for 24 h, cell viability was measured by MTT assay. PC12 cells were cultured with 400 µM of CORT in the absence or presence of CGA (25 µg/ml) for 24 h, morphologies and specific marker of autophagosome were observed by transmission electron microscope (TEM) and confocal immunofluorescence microscopy, respectively. In addition, PC12 cells were treated with different doses of CGA (0, 6.25, 12.5, 25 or 50 µg/ml) with or without CORT (400 µM) for 24 h, cell viability and changes in the morphology were observed, and further analysis of apoptotic and autophagic proteins, and expression of AKT/mTOR signaling pathway were carried out by Western blot. Specific inhibitors of autophagy 3-Methyladenine (3-MA) and chloroquine (CQ) were added to the PC12 cells cultures to explore the potential role of autophagy in CORT-induced neuronal cell apoptosis. RESULTS: Besides decreasing PC12 cell activity, CORT could also induce autophagy and apoptosis of PC12 cells, while CGA could reverse these effects. In addition, CGA treatment regulated AKT/mTOR signaling pathway in PC12 cells. CGA, similar to 3-MA and QC, significantly inhibited CORT-induced apoptosis in PC12 cells. CONCLUSIONS: Our results provide a new molecular mechanism for the treatment of CORT-induced neurotoxicity by CGA, and suggest CGA may be a potential substance which is can alleviate depression.

The effect of fluoxetine on astrocyte autophagy flux and injured mitochondria clearance in a mouse model of depression.

Although multiple hypotheses had been proposed to clarify the causes of depression, the accurate pathogenesis and effective treatment of depression still need to be solved. Pathological change of astrocytes has been recognized to play a pivotal role in depression. Fluoxetine is the first selective serotonin reuptake inhibitor, however, the underlying mechanisms of fluoxetine are incompletely excavated. Emerging evidence shows that fluoxetine promotes autophagic processes in tumor cells. However, whether astrocytic autophagy gets involved in the cytoprotection of fluoxetine on astrocytes in depression treatment remains unexplored. Here we prepared chronic mild stress (CMS)-induced mouse model and treated mice with fluoxetine (10 mg/kg) for 4 weeks to determine the correlation between proautophagic effect of fluoxetine and astrocyte protection in depression. Primary hippocampal astrocytes were cultured to investigate the potential mechanism of fluoxetine in regulating astrocyte autophagy. We found that fluoxetine (10 mg/kg) treatment promoted autophagosome formation and increased clearance of injured mitochondria, consequently protected astrocytes in CMS model mice. Fluoxetine (10 µM) could also promote the autophagic flux unblocked via enhancing fusion of autophagosomes with lysosomes in primary astrocytes. Moreover, fluoxetine promoted mitophagy by increased colocalization of autophagosomes and mitochondria, eliminating damaged mitochondria in corticosterone-treated astrocytes. Further in vitro study showed that p53 presence is required for fluoxetine activated autophagy flux and fluoxetine promotes astrocytic autophagy in a p53-dependent mechanism. Collectively, this work gives us insights into a novel approach to treat depression depending on astrocytes, and provides a promising molecular target for the development of antidepressant drugs besides regulating neurotransmitters.

Sex Difference in Corticosterone-Induced Insulin Resistance in Mice.

Prolonged exposure to glucocorticoids (GCs) causes various metabolic derangements. These include obesity and insulin resistance, as inhibiting glucose utilization in adipose tissues is a major function of GCs. Although adipose tissue distribution and glucose homeostasis are sex-dependently regulated, it has not been evaluated whether GCs affect glucose metabolism and adipose tissue functions in a sex-dependent manner. In this study, high-dose corticosterone (rodent GC) treatment in C57BL/6J mice resulted in nonfasting hyperglycemia in male mice only, whereas both sexes displayed hyperinsulinemia with normal fasting glucose levels, indicative of insulin resistance. Metabolic testing using stable isotope-labeled glucose techniques revealed a sex-specific corticosterone-driven glucose intolerance. Corticosterone treatment increased adipose tissue mass in both sexes, which was reflected by elevated serum leptin levels. However, female mice showed more metabolically protective adaptations of adipose tissues than did male mice, demonstrated by higher serum total and high-molecular-weight adiponectin levels, more hyperplastic morphological changes, and a stronger increase in mRNA expression of adipogenic differentiation markers. Subsequently, in vitro studies in 3T3-L1 (white) and T37i (brown) adipocytes suggest that the increased leptin and adiponectin levels were mainly driven by the elevated insulin levels. In summary, this study demonstrates that GC-induced insulin resistance is more severe in male mice than in female mice, which can be partially explained by a sex-dependent adaptation of adipose tissues.

d-Limonene protects PC12 cells against corticosterone-induced neurotoxicity by activating the AMPK pathway.

The stress-induced hormone corticosterone initiates oxidative stress and inflammatory responses, culminating in cell apoptosis and neurological changes. We assessed the effects of d-Limonene on a PC12 cellular model of corticosterone-induced neurotoxicity, and whether these effects involved the AMP-activated protein kinase (AMPKα) pathway. PC12 cells were treated with corticosterone with or without d-limonene for 24 h. Western blots were performed to measure activation of AMPK pathway members [Silent mating type information regulation 2 homolog-1 (SIRT1), AMPKα, and nuclear factor (NFκB)], reactive oxygen species, inflammatory cytokines, and markers of apoptosis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) was used to measure cell death after treatment. d-Limonene reversed the effects of corticosterone on PC12 cells: it decreased the levels of malondialdehyde (MDA) and nitric oxide (NO), activities of NADPH oxidase (p67-phox and p47-phox), expression of pro-inflammatory markers [inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin 6 (IL-6), interleukin 1ß (IL-1ß), and tumor necrosis factor α (TNF-α)], and expression of pro-apoptotic proteins [Bcl2 associated with X protein (Bax) and cleaved caspase-3)]. d-Limonene also increased levels of the antioxidant enzymes superoxide dismutase 1 (SOD1) and heme oxygenase 1 (HO-1) and the anti-apoptotic protein Bcl-2 while decreasing the number of TUNEL-positive cells. d-limonene significantly activated AMPKα and suppressed NF-κB nuclear translocation through up-regulation of SIRT1. Addition of compound C, an AMPK inhibitor, severely weakened these neuroprotective effects of d-limonene. d-Limonene has a neuroprotective effect on corticosterone-induced PC12 cell injury induced by activating the AMPKα signaling pathway, and thereby inhibiting reactive oxygen species and inflammatory factors. These data suggest that d-limonene might protect against neuronal death to improve depressive symptoms.

Involvement of mitochondrial apoptotic pathway and MAPKs/NF-κ B inflammatory pathway in the neuroprotective effect of atractylenolide III in corticosterone-induced PC12 cells.

Atractylenolide III (ATL-III), a sesquiterpene compound isolated from Rhizoma Atractylodis Macrocephalae, has revealed a number of pharmacological properties including anti-inflammatory, anti-cancer activity, and neuroprotective effect. This study aimed to evaluate the cytoprotective efficiency and potential mechanisms of ATL-III on corticosterone injured rat phaeochromocytoma (PC12) cells. Our results demonstrate that ATL-III increases cell viability and reduces the release of lactate dehydrogenase (LDH). The results suggest that ATL-III protects PC12 cells from corticosterone-induced injury by inhibiting the intracellular Ca2+ overloading, inhibiting the mitochondrial apoptotic pathway and modulating the MAPK/NF-ΚB inflammatory pathways. These findings provide a novel insight into the molecular mechanism by which ATL-III protected the PC12 cells against corticosterone-induced injury for the first time. Our results provide the evidence that ATL-III may serve as a therapeutic agent in the treatment of depression.

Protective effect of pig brain polypeptides against corticosterone-induced oxidative stress, inflammatory response, and apoptosis in PC12 cells.

OBJECTIVE: Pig brain polypeptides (PBP), active polypeptides hydrolysate extracted from fresh porcine brain tissue, has been shown to have neuroprotective effects in both in vitro and in vivo studies. The present study aimed to explore the molecular mechanisms underlying the neuroprotective effects of PBP in corticosterone (CORT)-induced rat adrenal pheochromocytoma PC12 cells. METHODS: Cell viability and lactate dehydrogenase (LDH) release were measured in PC12 cells induced with 200 µM CORT in the presence or absence of various concentrations of PBP for 48 h. Intracellular reactive oxygen species (ROS) generation, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and glutathione (GSH) content were examined to analyze the effect of PBP on CORT-induced oxidative stress. The levels of pro-inflammatory factors, the percentage of apoptotic cells, and apoptosis-related protein expression in PC12 cells were determined. RESULTS: PBP is mainly composed of protein subunits with molecular weights ranging from 1000 to 10,000 Da. PBP treatment increased cell viability and decreased the release of LDH in CORT-stimulated PC12 cells. Moreover, PBP reduced the level of CORT-induced oxidative stress by decreasing ROS levels and increasing SOD, GSH-Px activities and GSH content. PBP had an inhibitory effect on the CORT-induced inflammatory response through inhibition of the NF-κB signaling pathway. PBP also inhibited CORT-induced apoptosis by downregulating the mitochondrial apoptotic signaling pathway. CONCLUSION: These results suggest that PBP exerts a neuroprotective effect against CORT-induced cell injury by inhibiting oxidative stress, inflammation, and apoptosis. PBP could act as a neuroprotective agent against nerve injury induced by CORT.

Transcriptome profiles of corticosterone-induced cytotoxicity reveals the involvement of neurite growth-related genes in depression.

Corticosterone (CORT), the main HPA-axis glucocorticoid hormone in rodents, is involved in the regulation of animal stress responses. However, the neural mechanisms underlying the effects of corticosteroids on depression are yet to be elucidated. We found that fluoxetine reversed neurite growth inhibition induced by CORT in PC12 cells, a widely used model system for neurobiological and neurotoxicological studies. Transcriptome profiling showed that 1,609 genes were up-regulated, whereas 1,764 genes were down-regulated significantly in the CORT group in comparison with the Control group. Of them, the expression of 589 DEGs was reversed after fluoxetine treatment, and genes related to cell morphogenesis, neurite growth, and immune function were involved in the neuroprotective effect of fluoxetine against CORT. Furthermore, expression of neurite growth-related genes, such as such as Calpain 2 (Capn2), vesicle-associated membrane protein 7 (Vamp7) and C-type natriuretic peptide (Cnp), altered in a brain region- or treatment-specific manner in the animal models of depression. Therefore, the interaction between stress, glucocorticoids, and neurite growth inhibition may be a candidate pathophysiology underlying major depressive disorder (MDD), and the identification of Capn2, Vamp7 and Cnp might provide insight into treatment of MDD.

Corticosterone rather than ethanol epigenetic programmed testicular dysplasia caused by prenatal ethanol exposure in male offspring rats.

Prenatal ethanol exposure (PEE) could affect offspring's testicular development. This study aimed to illuminate its intrauterine origin and the programming mechanism caused by PEE. Pregnant Wistar rats were given ethanol (4 g/kg.d) by gavage administration during gestational days (GD) 9-20. Serum samples and testes of male offspring rats were collected on GD20, postnatal week (PW) 6, and PW12. We found that PEE induced testicular morphological abnormality, low serum testosterone levels, expressive suppression of 3ß-hydroxysteroid dehydrogenase (3ß-HSD), and low acetylation levels of histone 3 lysine 14 (H3K14ac) of 3ß-HSD before and after birth. In utero, when fetal rats were overexposed to corticosterone by PEE, the expression levels of testicular glucocorticoid receptor (GR) and histone deacetylase 2 (HDAC2) were increased, while that of steroidogenic factor 1 (SF1) was decreased. In vitro, corticosterone (rather than ethanol) at 500 to 2,000 nM concentration decreased testosterone production and 3ß-HSD expression in a concentration-dependent manner. Moreover, corticosterone downregulated SF1 and upregulated HDAC2 via activating GR, accompanied by a low H3K14ac level of 3ß-HSD; SF1 overexpression could reverse the increased HDAC2 expression, and knockdown of HDAC2 could partially reverse the inhibitory effects of corticosterone on H3K14ac level and 3ß-HSD expression but not on SF1 expression. Taken together, PEE caused testicular dysplasia in male offspring rats, which was associated with corticosterone-induced low-functional programming of 3ß-HSD through the GR/SF1/HDAC2/H3K14ac pathway. This study provides new academic perspectives to illuminate the theory of 'Developmental Origins of Health and Disease.'

Camellia euphlebia protects against corticosterone-induced apoptosis in differentiated PC12 cells by regulating the mitochondrial apoptotic pathway and PKA/CREB/BDNF signaling pathway.

Camellia euphlebia is a Chinese folk medicine, known for its multiple pharmacological properties. Our previous studies have demonstrated its antidepressant activity by several animal models of depression. The possible underlying mechanism was further explored by investigating the neuroprotective effect of Camellia euphlebia extract (CEE) on corticosterone-induced apoptosis in neuronally differentiated PC12 cells. The results of methyl-thiazolyl-tetrazolium assay, lactate dehydrogenase release assay, Hoechst 33342 staining, propidium iodide staining, AV-FITC/PI double staining and DNA fragmentation analysis consistently indicated that pretreatment of PC12 cells with CEE at 20-80 µg/mL significantly reversed 300 µmol/L corticosterone-induced apoptosis in a dose dependent manner. Furthermore, intracellular mitochondrial membrane potential, reactive oxygen species accumulation, calcium level, Bcl-2/Bax ratio, caspase activity were assessed, and the results indicated that CEE exhibited its anti-apoptotic effect through the regulation of mitochondrial apoptosis pathway. Additionally, CEE increased the cyclic adenosine monophosphate-dependent protein kinase (PKA) level, which phosphorylated cAMP response element binding protein (CREB), and finally elevated the mRNA expression of brain-derived neurotrophic factor (BDNF) gene. It is speculated that the antidepressant effect of CEE in vivo may be associated with the cytoprotection of neuron damaged by corticosterone, and the cellular mechanism involves the mitochondrial-mediated apoptosis and PKA-CREB-BDNF signaling pathway.

TPPU, a sEH Inhibitor, Attenuates Corticosterone-Induced PC12 Cell Injury by Modulation of BDNF-TrkB Pathway.

High level of corticosterone (CORT) is toxic to neurons and plays an important role in depression-like behavior and chronic stress. Our previous study showed that TPPU, a soluble epoxide hydrolase (sEH) inhibitor (sEHI), induces an antidepressant effect in animal models. However, the underlying mechanism is not clear. In this study, we investigated the protective effect of TPPU on PC12 cells against CORT-induced cytotoxicity and its underlying mechanism. We found that TPPU and the sEH substrate epoxyeicosatrienoic acids (EETs) protected PC12 cells from the CORT-induced injury by increasing cell viability and inhibiting apoptosis. Furthermore, TPPU and EETs also blocked the CORT-mediated downregulation of BDNF. Blocking the BDNF-TrkB pathway by the TrkB inhibitor K252a abolished the protective effect of TPPU. Taken together, our results suggest that sEHI could protect PC12 cells against the CORT-induced cytotoxicity via the BDNF-TrkB signaling pathway.

Prenatal nicotine exposure retards osteoclastogenesis and endochondral ossification in fetal long bones in rats.

This study investigated the mechanisms underlying the retarded development of long bone in fetus by prenatal nicotine exposure (PNE) which had been demonstrated by our previous work. Nicotine (2.0 mg/kg.d) or saline was injected subcutaneously into pregnant rats every morning from gestational day (GD) 9 to 20. Fetal femurs or tibias were harvested for analysis on GD 20. We found massive accumulation of hypertrophic chondrocytes and a delayed formation of primary ossification center (POC) in the fetal femur or tibia of rat fetus after PNE, which was accompanied by a decreased amount of osteoclasts in the POC and up-regulated expression of osteoprotegerin (OPG) but by no obvious change in the expression of receptor activator of NF-κB ligand (RANKL). In primary osteoblastic cells, both nicotine (0, 162, 1620, 16,200 ng/ml) and corticosterone (0, 50, 250, 1250 nM) promoted the mRNA expression of OPG but concentration-dependently suppressed that of RANKL. Furthermore, blocking α4ß2-nicotinic acetylcholine receptor (α4ß2-nAChR) or glucocorticoid receptor rescued the above effects of nicotine and corticosterone, respectively. In conclusion, retarded osteoclastogenesis may contribute to delayed endochondral ossification in long bone in fetal rats with PNE. The adverse effects of PNE may be mediated via the direct effect of nicotine and indirect effect of maternal corticosterone on osteoblastic cells.

Neuroprotective effect of a physiological ratio of testosterone and estradiol on corticosterone-induced apoptosis in PC12 cells via Traf6/TAK1 pathway.

Clinical and experimental studies suggested that testosterone or estradiol alone supplementation may have antidepressant-like effects. However, the synergistic effect of testosterone/estradiol on the treatment of depression and the underlying mechanism remain largely unknown. Here, we hypothesized that an appropriate dosage of testosterone combined with estradiol may became a new therapeutic strategy in depression. Our results indicated that an appropriate testosterone/estradiol ratio of 10:1 (10-8 mol/L testosterone and 10-9 mol/L estradiol) was found, which has a significant synergistic anti-apoptotic effect on PC12 cells injury stimulated by corticosterone. We then confirmed the synergistic effect of the defined testosterone/estradiol ratio in PC12 cells mainly depend on the inhibitory activation of Traf6/TAK1 signaling pathway. Furthermore, we found that the defined testosterone/estradiol ratio could suppress the expression and ubiquitination of Traf6 protein through AR/ERα-mediated pathways. Finally, endogenous interactions of Traf6 with AR/ERα in PC12 cells were found using co-immunoprecipitation assays, and further verified how the defined testosterone/estradiol ratio plays a synergistic role in injury of PC12 cells. The current study demonstrated that an appropriate testosterone/estradiol ratio has a synergistic effect on PC12 cells injury induced by corticosterone through suppressing the activation of Traf6/TAK1 signaling pathway, suggesting that testosterone/estradiol might synergistically protect against neuronal apoptosis to ameliorate depressive symptoms.

Isobutylhydroxyamides from Sichuan Pepper and Their Protective Activity on PC12 Cells Damaged by Corticosterone.

The pericarp of Zanthoxylum bungeanum Maxim., commonly known as Sichuan pepper, is a widely used spice to remove fishy odor and add palatable taste. A phytochemical investigation of the 95% ethanol extract of Sichuan pepper resulted in the isolation of 21 isobutylhydroxyamides, including 8 new ones named ZP-amides G-N, among which the chiral resolution of racemic ZP-amide A and ZP-amide B was successfully accomplished. The protective activity on corticosterone-treated PC12 cells of the isolated isobutylhydroxyamides was also evaluated. The new compounds 3-5 and the known compounds 1, 1a, 2, 2a, 11, and 15 improved the survival rate of PC12 cells. The bioactivity studies disclosed the potential of Sichuan pepper to be developed as new neuroprotective functional food.

Targeting the Endocannabinoid/CB1 Receptor System For Treating Major Depression Through Antidepressant Activities of Curcumin and Dexanabinol-Loaded Solid Lipid Nanoparticles.

BACKGROUND/AIMS: This study investigated the underlying mechanisms of the antidepressant effects of curcumin and dexanabinol-loaded solid lipid nanoparticles in corticosterone-induced cell and mice depression models. METHODS: Curcumin and dexanabinol-loaded solid lipid nanoparticles (Cur/SLNs-HU-211) were synthesized via an emulsifcation and low-temperature solidification method. Antidepressant activities of nanoparticles in a corticosterone-induced major depression model were investigated by MTT assay, cellular uptake by flow cytometry, behaviour by Forced Swimming Test and rotarod test, neurotransmitters by High Performance Liquid Chromatography, Western blotting, qPCR and immunofluorescence. RESULTS: Treatment with Cur/SLNs-HU-211 induced greater dopamine (DA)/5-hydroxytryptamine (5-HT) release with reduced corticosterone-induced apoptotic cell death in PC12 cells. Additionally, in vivo Cur/SLNs-HU-211 significantly induced recovery from depressive behaviour with increased DA/5-HT levels, CB1 mRNA levels and CB1, p-MEK1 and p-ERK1/2 protein expression levels in the hippocampus and striatum. Cur/SLNs-HU-211 improved CB1 expression and inspired the proliferation of astrocytes in the hippocampus and striatum, exerted neuroprotective effects by preventing corticosterone -induced BDNF/NeuN expression reduction. CONCLUSION: Our study implies that Cur/SLNs-HU-211 may be a useful approach for treatment of major depression.

Brain antioxidant effect of mirtazapine and reversal of sedation by its combination with alpha-lipoic acid in a model of depression induced by corticosterone.

BACKGROUND: Depression is accompanied by activated neuro-oxidative and neuro-nitrosative pathways, while targeting these pathways has clinical efficacy in depression. This study aimed to investigate the effects of mirtazapine (MIRT) alone and combined with alpha-lipoic acid (ALA) against corticosterone (CORT) induced behavioral and oxidative alterations. METHODS: Male mice received vehicle or CORT 20mg/kg during 14 days. From the 15th to 21st days they were divided in groups administered: vehicle, MIRT 3mg/kg or the combinations MIRT+ALA100 or MIRT+ALA200. On the 21st day of treatment, the animals were subjected to behavioral tests. Twenty-four hours after the last drug administration hippocampus (HC) and striatum (ST) were dissected for the determination reduced glutathione (GSH), lipid peroxidation (LP) and nitrite levels. RESULTS: CORT induced anxiety- and depressive-like behaviors as observed by increased immobility time in the tail suspension test and decreased sucrose consumption. MIRT or MIRT+ALA are effective in reversing anxiety- and depressive-like behaviors induced by CORT. CORT and MIRT alone prolonged sleeping time and this effect was reversed by MIRT+ALA. CORT significantly increased LP, which was reversed by MIRT or MIRT+ALA. Nitrite levels were increased in CORT-treated animals and reversed by MIRT+ALA200 (HC), MIRT or MIRT+ALA (ST). LIMITATION: A relative small sample size and lack of a washout period between drug administration and behavioral testing. CONCLUSIONS: MIRT or MIRT+ALA reverse CORT-induced anxiety- and depressive-like behaviors probably via their central antioxidant effects. Augmentation of MIRT with ALA may reverse sedation, an important side effect of MIRT. Randomized controlled studies are needed to examine the clinical efficacy of this combination in human depression.