The effects of chronic administration of tranylcypromine and rimonabant on behaviour and protein expression in brain regions of the rat

Recent findings indicate that CB1 receptor blockade might be relevant to the action of antidepressant drugs as inhibition of endocannabinoid function can increase synaptic availability of neurotransmitters; an effect also seen with chronic antidepressant drug treatment. Chronic treatments with established antidepressants also lead to raised brain BDNF levels. The aim of this study was to compare the effects of rimonabant (an inverse agonist/antagonist of CB1 receptors) with those of the antidepressant tranylcypromine (TCP), on behaviour and expression of BDNF/CREB signalling pathways in rat brain.Daily (i.p.) injections of vehicle or TCP (10 mg/kg) or rimonabant (2 mg/kg) were given for 14 days. Locomotor activity (LMA) and a conditional emotional response (CER) were measured in addition to levels of BDNF and CREB/phospho-CREB, using immunoblotting, in the frontal cortex, hippocampus, striatum and cerebellum. The velocity of movement was increased significantly on the 3rd, but not 9th, day of TCP treatment versus vehicle-treated rats (p < 0.05) while rimonabant had no effect. There were no significant changes in grooming or freezing behaviours after rimonabant or TCP compared to vehicle-treated rats. Rearing was significantly reduced by TCP treatment on the 3rd, but not 9th, day of treatment (p < 0.001) while rimonabant had no effect. BDNF levels were significantly increased in the frontal cortex after TCP (p < 0.05) but not by rimonabant. Neither TCP nor rimonabant significantly affected CREB or p-CREB expression.In conclusion, chronic administration of TCP to rats increased BDNF expression in the frontal cortex but no similar effect was observed with rimonabant indicating that rimonabant does not show antidepressant drug-like responses after chronic treatment.     

Brain-derived neurotrophic factor prevents phencyclidine-induced apoptosis in developing brain by parallel activation of both the ERK and PI-3K/Akt pathways

Phencyclidine is an N-methyl d-aspartate receptor (NMDAR) blocker that has been reported to induce neuronal apoptosis during development and schizophrenia-like behaviors in rats later in life. Brain-derived neurotrophic factor (BDNF) has been shown to prevent neuronal death caused by NMDAR blockade, but the precise mechanism is unknown. This study examined the role of the phosphatidylinositol-3 kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) pathways in BDNF protection of PCP-induced apoptosis in corticostriatal organotypic cultures. It was observed that BDNF inhibited PCP-induced apoptosis in a concentration-dependent fashion. BDNF effectively prevented PCP-induced inhibition of the ERK and PI-3K/Akt pathways and suppressed GSK-3β activation. Blockade of either PI-3K/Akt or ERK activation abolished BDNF protection. Western blot analysis revealed that the PI-3K inhibitor LY294002 prevented the stimulating effect of BDNF on the PI-3K/Akt pathway, but had no effect on the ERK pathway. Similarly, the ERK inhibitor PD98059 prevented the stimulating effect of BDNF on the ERK pathway, but not the PI-3K/Akt pathway. Co-application of LY294002 and PD98059 had no additional effect on BDNF-evoked activation of Akt or ERK. However, concurrent exposure to PD98059 and LY294002 caused much greater inhibition of BDNF-evoked phosphorylation of GSK-3β at serine 9 than did LY294002 alone. Finally, either BDNF or GSK-3β inhibition prevented PCP-induced suppression of cyclic-AMP response element binding protein (CREB) phosphorylation. These data demonstrate that the protective effect of BDNF against PCP-induced apoptosis is mediated by parallel activation of the PI-3K/Akt and ERK pathways, most likely involves inhibition of GSK-3β and activation of CREB.     

Cytoprotective and anti-inflammatory effects of spinasterol via the induction of heme oxygenase-1 in murine hippocampal and microglial cell lines

Spinasterol, which is isolated from the aerial parts of Aster scaber Thunb. (Asteraceae), is involved in various biological activities. In this study, we report the efficacy of spinasterol in effectively modulating the regulation of antioxidative and anti-inflammatory activity through the upregulation of heme oxygenase (HO)-1 in murine hippocampal HT22 cells and BV2 microglia. We showed that spinasterol increased the cellular resistance of HT22 cells to oxidative injury caused by the glutamate-induced cytotoxicity by extracellular signal-regulated kinase (ERK) pathway-dependent expression of HO-1. Furthermore, spinasterol suppressed the lipopolysaccharide (LPS)-induced expression of pro-inflammatory enzymes and inflammatory mediators in BV2 microglia. Spinasterol also suppressed the production of nitric oxide (NO), prostaglandin E2 (PGE?), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) through extracellular signal-regulated kinase (ERK) pathway-dependent expression of HO-1. These results suggest that spinasterol has a therapeutic potential against neurodegenerative diseases that are caused by oxidative stress and neuroinflammation.     

The endocrine effects of mercury in humans and wildlife

Mercury (Hg) is well studied and research continues as our knowledge of its health risks increases. One expanding area of research not well emphasized to date is the endocrine effects of Hg. This review summarizes the existing literature on the effects of Hg on the endocrine system and identifies gaps in the knowledge. It focuses on the thyroid, adrenal, and reproductive systems, including the accumulation of Hg in the endocrine system, sex differences that are manifested with Hg exposure, reproductive effects in male and female animals including humans, and Hg effects on the thyroid and adrenal systems. We concluded that there are five main endocrine-related mechanisms of Hg across these systems: (a) accumulation in the endocrine system; (b) specific cytotoxicity in endocrine tissues; (c) changes in hormone concentrations; (d) interactions with sex hormones; and (e) up-regulation or down-regulation of enzymes within the steroidogenesis pathway. Recommendations for key areas of research to better understand how the endocrine effects of Hg affect human and wildlife health were developed, and include increasing the amount of basic biological information available about Hg and wildlife species, exploring the role of Hg in the presence of other stressors and chemicals, understanding sublethal and indirect effects of Hg on adverse outcomes, developing better methods to extrapolate effects across species, and understanding the effects of Hg on multiple organ systems following exposure of an animal. Greater inclusion of endocrine endpoints in epidemiological and field studies on humans and wildlife will also advance the research in this area.     

The effects of acute and long-term lithium treatments on trkB neurotrophin receptor activation in the mouse hippocampus and anterior cingulate cortex

As brain-derived neurotrophic factor (BDNF) and its receptor trkB are linked to the etiology and treatment of mood disorders, we examined the effects of acute and long-term treatment of mood-stabilizer lithium on trkB activation and signaling and BDNF levels in the mouse anterior cingulate cortex (AC) and hippocampus (HC). The trkB activity was measured using specific antibodies against the phosphorylated trkB catalytic domain (pY705/6) and the shc binding site (pY515). In the AC, both acute and long-term LiCl treatment enhanced the pY705/6 of trkB. In contrast, acute or long-term LiCl treatment did not significantly alter the pY705/6 of trkB in the HC. Interestingly, however, acute LiCl treatment significantly reduced the phosphorylation of cAMP related element binding protein (CREB), a major intracellular target of trkB, in the HC. Moreover, pY515 of trkB in the AC and HC was not altered by any of the treatment. Also, prolonged LiCl treatment had no significant effects on BDNF levels or CREB activation in either the AC or HC. The present results suggest that acute and long-term lithium treatment induces trkB activation in the AC but not in the HC. The activation of CREB is, however, significantly reduced in the HC after acute LiCl treatment.     

高镁对体外培养原代神经干细胞分化命运的影响及其机制

目的 探索高镁对神经发生过程中神经干细胞分化命运的影响及其潜在机制.方法 从C57/BL6胎鼠大脑中分离神经干细胞,通过添加硫酸镁(MgSO4)调节培养基镁离子浓度并诱导分化,第6天通过免疫细胞化学荧光染色观察成熟神经元标记物β-Ⅲ tubulin(Tuj 1)和胶质细胞标记物胶质原纤维酸性蛋白(GFAP)的阳性细胞比例,Western blot检测ERK1/2表达,qPCR检测Tuj1、GFAP的mRNA水平.结果 高镁组(0.8 mM和1.0 mM)相比于对照组(0.6 mM),Tuj1阳性细胞的比例增加,GFAP阳性细胞比例减少,Tuj1表达上调,GFAP表达下调,pERK/ERK上调,差异具有统计学意义(P＜0.05),高镁组添加ERK抑制剂PD0325901后,以上指标与对照组比较差异无统计学意义(P＞0.05).结论 高镁可促进神经干细胞向神经元分化,抑制其向神经胶质细胞分化,其作用可能与ERK1/2的激活有关.     

Protective effects of hesperidin against oxidative stress of tert-butyl hydroperoxide in human hepatocytes

Increasing evidence regarding free radical generating agents and the inflammatory process suggest that accumulation of reactive oxygen species (ROS) could involve hepatotoxicity. Hesperidin, a naturally occurring flavonoid presents in fruits and vegetables, has been reported to exert a wide range of pharmacological effects that include antioxidant, anti-inflammatory, antihypercholesterolemic, and anticarcinogenic actions. However, the cytoprotection and mechanism of hesperidin to neutralize oxidative stress in human hepatic L02 cells remain unclear. In this work, we assessed the capability of hesperidin to prevent tert-butyl hydroperoxide (t-BuOOH)-induced cell damage by augmenting cellular antioxidant defense. Hesperidin significantly protected hepatocytes against t-BuOOH-induced cell cytotoxicity, such as mitochondrial membrane potential (MMP) deplete and lactate dehydrogenase (LDH) release. Hesperidin also remarkably prevented indicators of oxidative stress, such as the ROS and lipid peroxidation level in a dose-dependent manner. Western blot showed that hesperidin facilitated ERK/MAPK phosphorylation which appeared to be responsible for nuclear translocation of Nrf2, thereby inducing cytoprotective heme oxygenase-1 (HO-1) expression. Based on the results described above, it suggested that hesperidin has potential as a therapeutic agent in the treatment of oxidative stress-related hepatocytes injury and liver dysfunctions.     

High dose hydrocortisone immediately after trauma may alter the trajectory of PTSD: Interplay between clinical and animal studies

High-dose corticosteroids have been reported to reduce symptoms of acute stress and post-traumatic stress in polytrauma patients and in animal studies. The underlying mechanism of action remains largely unclear. These issues were addressed in parallel in the clinical and preclinical studies below. In this preliminary study, 25 patients with acute stress symptoms were administered a single intravenous bolus of high-dose hydrocortisone (100–140 mg) or placebo within 6 h of a traumatic event in a prospective, randomized, double-blind, placebo-controlled pilot study. Early single high-dose hydrocortisone intervention attenuated the core symptoms of both the acute stress and of subsequent PTSD in patients. High-dose hydrocortisone treatment given in the first few hours after a traumatic experience was associated with significant favorable changes in the trajectory of exposure to trauma, as expressed by the reduced risk of the development of PTSD post-trauma. In parallel, a comparative study of morphological arborization in dentate gyrus and its modulating molecules was performed in stress-exposed animals treated with high-dose hydrocortisone. Steroid-treated stressed animals displayed significantly increased dendritic growth and spine density, with increased levels of brain-derived neurotrophic factor (BDNF) and obtunded postsynaptic density-95 (PSD-95) levels. The animal study provided insights into the potential mechanism of this intervention, as it identified relevant morphological and biochemical associations to the clinical observations. Thus, evidence from clinical and animal studies suggests that there is a “window of opportunity” in the early aftermath of trauma to help those who are vulnerable to the development of chronic PTSD.     

Neuropeptide S in the basolateral amygdala mediates an adaptive behavioral stress response in a rat model of posttraumatic stress disorder by increasing the expression of BDNF and the neuropeptide YY1 receptor

Neuropeptide S (NPS) is a regulatory peptide that has anxiolytic and arousal-promoting effects in rodents. We used an animal model of posttraumatic stress disorder (PTSD) to assess long-term behavioral effects of a single dose of NPS, microinjected into the basolateral amygdala (BLA) 1 h following exposure to predator-scent stress (PSS). To elucidate the molecular mechanism by which NPS attenuates behavioral stress responses, expression levels of neuropeptide Y (NPY), NPY-Y1 receptor (NPY-Y1R), and brain-derived neurotrophic factor (BDNF) were evaluated in the hippocampus. The behavioral and molecular effects of NPS receptor antagonist (NPS-RA), NPY-Y1R antagonist (NPY-Y1RA), or both administered centrally were evaluated in the same manner. Circulating corticosterone levels were measured at different time points following PSS-exposure. Immediate post-exposure treatment with NPS had a marked protective effect; BLA microinfusion of NPS completely abolished the extreme behavioral response to PSS, restored the decreased expression of BDNF and, unexpectedly, PY-Y1R, but didn't affect the decreased expression of NPY. BLA microinfusion of both NPY-Y1RA and NPS-RA together had an additive effect, which completely prevented the anxiolytic effects of NPS in rats exposed to PSS and disrupted the expression of NPY-Y1R in the hippocampus following NPS infusion. It may therefore be hypothesized that NPS acts, directly or indirectly, on both the NPY-Y1R and NPS receptors and that the cross-talk between NPS and NPY-Y1R may be necessary for the anxiolytic effects of NPS post-exposure. The NPS system might thus contribute to a potential endogenous mechanism underlying the shift towards adaptive behavioral response and thereby might be relevant as a pharmacological target for attenuating stress-related sequelae.     

Inhibitory effects of wogonin on the invasion of human breast carcinoma cells by downregulating the expression and activity of matrix metalloproteinase-9

Wogonin, a naturally occurring monoflavonoid extracted from Scutellariae radix, has been shown to possess tumor therapeutic potential in vitro and in vivo. However, the effects of wogonin on tumor cells invasion remains poorly understood. In this study, we performed in vitro experiments to investigate the anti-invasive and anti-metastatic activity of wogonin in MDA-MB-231 human breast carcinoma cells. Wogonin caused a concentration-dependent suppression of cell migration, adhesion and invasion. The mechanism revealed that wogonin significantly inhibited the expression and activity of both endogenous and phorbol-12-myristate-13-acetate (PMA)-induced matrix metalloproteinase-9 (MMP-9) potentially associating with the suppression of translocation of protein kinase C (PKC) δ and phosphorylation of extracellular signal-regulated kinase (ERK1/2). These results suggested that wogonin could inhibit the invasion of tumor cells by downregulating the expression and activity of MMP-9, the possible targets may be PKCδ and ERK1/2.     

Isorhamnetin protects against oxidative stress by activating Nrf2 and inducing the expression of its target genes

Isorhamentin is a 3′-O-methylated metabolite of quercetin, and has been reported to have anti-inflammatory and anti-proliferative effects. However, the effects of isorhamnetin on Nrf2 activation and on the expressions of its downstream genes in hepatocytes have not been elucidated. Here, we investigated whether isorhamnetin has the ability to activate Nrf2 and induce phase II antioxidant enzyme expression, and to determine the protective role of isorhamnetin on oxidative injury in hepatocytes. In HepG2 cells, isorhamnetin increased the nuclear translocation of Nrf2 in a dose- and time-dependent manner, and consistently, increased antioxidant response element (ARE) reporter gene activity and the protein levels of hemeoxygenase (HO-1) and of glutamate cysteine ligase (GCL), which resulted in intracellular GSH level increases. The specific role of Nrf2 in isorhamnetin-induced Nrf2 target gene expression was verified using an ARE-deletion mutant plasmid and Nrf2-knockout MEF cells. Deletion of the ARE in the promoter region of the sestrin2 gene, which is recently identified as the Nrf2 target gene by us, abolished the ability of isorhamnetin to increase luciferase activity. In addition, Nrf2 deficiency completely blocked the ability of isorhamnetin to induce HO-1 and GCL. Furthermore, isorhamnetin pretreatment blocked t-BHP-induced ROS production and reversed GSH depletion by t-BHP and consequently, due to reduced ROS levels, decreased t-BHP-induced cell death. In addition isorhamnetin increased ERK1/2, PKCδ and AMPK phosphorylation. Finally, we showed that Nrf2 deficiency blocked the ability of isorhamnetin to protect cells from injury induced by t-BHP. Taken together, our results demonstrate that isorhamnetin is efficacious in protecting hepatocytes against oxidative stress by Nrf2 activation and in inducing the expressions of its downstream genes.     

Arsenic-induced alteration in intracellular calcium homeostasis induces head kidney macrophage apoptosis involving the activation of calpain-2 and ERK in Clarias batrachus

We had earlier shown that exposure to arsenic (0.50 μM) caused caspase-3 mediated head kidney macrophage (HKM) apoptosis involving the p38-JNK pathway in Clarias batrachus. Here we examined the roles of calcium (Ca²⁺) and extra-cellular signal-regulated protein kinase (ERK), the other member of MAPK-pathway on arsenic-induced HKM apoptosis. Arsenic-induced HKM apoptosis involved increased expression of ERK and calpain-2. Nifedipine, verapamil and EGTA pre-treatment inhibited the activation of calpain-2, ERK and reduced arsenic-induced HKM apoptosis as evidenced from reduced caspase-3 activity, Annexin V-FITC-propidium iodide and Hoechst 33342 staining. Pre-incubation with ERK inhibitor U 0126 inhibited the activation of calpain-2 and interfered with arsenic-induced HKM apoptosis. Additionally, pre-incubation with calpain-2 inhibitor also interfered with the activation of ERK and inhibited arsenic-induced HKM apoptosis. The NADPH oxidase inhibitor apocynin and diphenyleneiodonium chloride also inhibited ERK activation indicating activation of ERK in arsenic-exposed HKM also depends on signals from NADPH oxidase pathway. Our study demonstrates the critical role of Ca²⁺ homeostasis on arsenic-induced HKM apoptosis. We suggest that arsenic-induced alteration in intracellular Ca²⁺ levels initiates pro-apoptotic ERK and calpain-2; the two pathways influence each other positively and induce caspase-3 mediated HKM apoptosis. Besides, our study also indicates the role of ROS in the activation of ERK pathway in arsenic-induced HKM apoptosis in C. batrachus.     

New advances in molecular mechanisms and the prevention of adriamycin toxicity by antioxidant nutrients

Anthracyclines (doxorubicin, daunorubicin, epirubicin, and idarubicin) are currently the most effective group of anti-neoplastic drugs used in clinical practice. Of these, doxorubicin (also called adriamycin) is a key chemotherapeutic agent in cancer treatment, although its use is limited as a consequence of the chronic and acute toxicity associated with this drug. The molecular mechanisms of doxorubicin account for both the anti-cancer and the toxic side effects. Many antioxidants have been assayed, with positive or negative results, to prevent the toxicity of doxorubicin. The present review has two main goals: (1) to report the latest findings regarding the molecular mechanisms of doxorubicin toxicity; (2) to update our understanding of the role of natural antioxidants in preventive therapy against doxorubicin-induced toxicity. This review provides new evidence for the chemoprevention of doxorubicin toxicity, making use of natural antioxidants – in particular vitamin E, vitamin C, coenzyme Q, carotenoids, vitamin A, flavonoids, polyphenol, resveratrol, antioxidant from virgin olive oil and selenium – and offers new insights into the molecular mechanisms of doxorubicin toxicity with respect to DNA damage, free radicals and other parameters.     

Current evidence on immunological and regenerative effects of menstrual blood stem cells seeded on scaffold consisting of amniotic membrane and silk fibroin in chronic wound

Wound healing process is a complex of overlapping and coordinated events progresses beyond the inflammatory phase toward wound resolution, whereas chronic wounds fail to terminate inflammatory phase and could not develop toward regenerative state. The immunopathology of chronic wounds has been attributed to the prolonged inflammation and dysregulation of microenvironments responsible for imbalance between pro-inflammatory and anti-inflammatory states, as well as cellular and tissue senescence.We here discuss that menstrual blood-derived mesenchymal stem cells (MenSCs) with their authentic functions especially immunosuppressive, angiogenic and migratory properties in combination with a bilayer amniotic membrane/nano-fibrous fibroin scaffold could bring about effective regenerative effects in healing of chronic wound. To debate, following evidences have been cumulated : 1) Persistent pro-inflammatory state in chronic wound bed could inhibit wound resolution; 2) MenSCs exhibit noticeable regenerative, immunosuppressive effects and immunomodulatory activity, 3) The migratory characteristics of MenSCs may not be sufficient for their homing to chronic wounds site, and 4) Bilayer scaffold composed of amniotic membrane and silk fibroin induces MenSCs differentiation into keratinocyte-like cells and stimulates skin regeneration.     

Disturbed Yin–Yang balance: stress increases the susceptibility to primary and recurrent infections of herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1), a neurotropic herpes virus, is able to establish a lifelong latent infection in the human host. Following primary replication in mucosal epithelial cells, the virus can enter sensory neurons innervating peripheral tissues via nerve termini. The viral genome is then transported to the nucleus where it can be maintained without producing infectious progeny, and thus latency is established in the cell. Yin–Yang balance is an essential concept in traditional Chinese medicine (TCM) theory. Yin represents stable and inhibitory factors, and Yang represents the active and aggressive factors. When the organism is exposed to stress, especially psychological stress caused by emotional stimulation, the Yin–Yang balance is disturbed and the virus can re-engage in productive replication, resulting in recurrent diseases. Therefore, a better understanding of the stress-induced susceptibility to HSV-1 primary infection and reactivation is needed and will provide helpful insights into the effective control and treatment of HSV-1. Here we reviewed the recent advances in the studies of HSV-1 susceptibility, latency and reactivation. We included mechanisms involved in primary infection and the regulation of latency and described how stress-induced changes increase the susceptibility to primary and recurrent infections.     

The role of nuclear factors as “Find-Me”/alarmin signals and immunostimulation in defective efferocytosis and related disorders

Efferocytosis as an apoptotic cell (AC) clearance mechanism facilitates the removal of dangerous and damaged cells, an important process in regulating normal homeostasis. Failure to correctly execute apoptosis and efferocytosis is associated with atherosclerosis, as well as chronic inflammatory and autoimmune disorders such as systemic lupus erythematosus (SLE). Effective and timely efferocytosis involves various molecules that act as “Find-Me” signals or as alarmins to quickly allow identification by phagocytic cells. In recent years, most of these molecules have been investigated, but less attention has been paid to the nuclear molecules associated with efferocytosis of ACs and necrotic cells (NCs). These molecules have several functions including acting as alarmin signals for faster recognition of ACs, facilitating the cleanup of ACs and for maintaining self-tolerance. The same group of molecules is also implicated in several inflammatory and autoimmune diseases. Previous studies have shown that these molecules also serve as targets for pharmacological agents such as necrostatins, recombinant Fcnb, anti-histone, neutralizing antibodies, calbiochem, aminophylline, activated protein C, CD24IgG recombinant fission protein, and recombinant thrombomodulin. Thus, greater understanding of these molecules/pathways will enable developments in the treatment and/or prevention of various disorders, especially autoimmune diseases. Here, we review current knowledge about the mechanisms by which nucleic acids, histones, nucleosomes and monosodium urate microcrystals (MSU) can act as alarmins/“Find-Me” signals, how they might be stimulated in defective efferocytosis and their function and importance as biomarkers for prognosis and treatment of atherosclerosis, inflammatory disorders and autoimmune diseases.