Role of brain-derived neurotrophic factor and nerve growth factor in the regulation of Neuropeptide W in vitro and in vivo

Nerve growth factor (NGF) and Brain-derived neurotrophic factor (BDNF) are neurotrophic factors involved in the growth, survival and functioning of neurons. In addition, a possible role of neurotrophins, particularly BDNF, in HPA axis hyperactivation has recently been proposed. Neuropeptide W (NPW) is an endogenous peptide ligand for the GPR7 and GPR8 and a stress mediator in the hypothalamus. It activates the HPA axis by working on hypothalamic corticotrophin-releasing hormone (CRH). No information is available about the interrelationships between neurotrophines like NGF/BDNF and NPW. We studied the effect and underlying mechanisms of NGF/BDNF on the production of NPW in PC12\ua0cells and hypothalamus. NGF time- and concentration-dependently stimulated the expression of NPW in PC12\ua0cells. The effect of NGF was blocked by the inhibition of PI3K/Akt signal pathway with specific inhibitors for PI3K or AktsiRNA for Akt while inhibition of ERK pathway had no effect. Moreover, BDNF concentration-dependently induced the expression of NPW mRNA and decreased the expression of NPY mRNA in primary cultured hypothalamic neurons which was also blocked by a PI3K kinase inhibitor. Finally, in\ua0vivo study showed that exogenous BDNF injected icv increased NPW production in the hypothalamus and this effect was reversed by a PI3 kinase inhibitor. These results and the fact that BDNF was able to stimulate the expression of CRH demonstrated that neurotrophines can modulate the expression of NPW in neuronal cells via the PI3K/Akt pathway and suggest that BDNF might be involved in functions of the HPA axis, at least in part by modulating the expression of NPW/NPY and CRH

Amiodarone-induced retinal neuronal cell apoptosis attenuated by IGF-1 via counter regulation of the PI3k/Akt/FoxO3a pathway

Amiodarone (AM) is the most effective antiarrhythmic agent currently available. However, clinical application of AM is limited by its serious toxic adverse effects including optic neuropathy. The purpose of this study was to explore the effects of AM and to assess if insulin-like growth factor-1 (IGF-1) could protect retinal neuronal cells from AM-induced apoptosis, and to determine the molecular mechanisms underlying the effects. Accordingly, the phosphorylation/activation of Akt and FoxO3a were analyzed by Western blot while the possible pathways involved in the protection of IGF-1 were investigated by application of various pathway inhibitors. The full electroretinogram (FERG) was used to evaluate in vivo effect of AM and IGF-1 on rat retinal physiological functions. Our results showed that AM concentration dependently caused an apoptosis of RGC-5 cells, while IGF-1 protected RGC-5 cells against this effect by AM. The protective effect of IGF-1 was reversed by PI3K inhibitors LY294002 and wortmannin as well as the Akt inhibitor VIII. AM decreased p-Akt and p-FoxO3a while increased the nuclear localization of FoxO3a in the RGC-5 cells. IGF-1 reversed the effect of AM on the p-Akt and p-FoxO3a and the nuclear translocation of FoxO3a. Similar results were obtained in primary cultured retinal ganglia cells. Furthermore, FERG in vivo recording in rats showed that AM decreased a-wave and b-wave of FERG while IGF-1 reversed the effects of AM. These data show that AM induced apoptosis of retinal neuronal cells via inhibiting the PI3K/Akt/FoxO3a pathway while IGF-1 protected RGC-5 cells against AM-induced cell apoptosis by stimulating this pathway

Nerve growth factor protects retinal ganglion cells against injury induced by retinal ischemia-reperfusion in rats

In this study, we investigated the protective effect of mouse nerve growth factor (NGF) on retinal ganglion cell (RGC) injury induced by retinal ischemia–reperfusion (RIR) in rats and explored its possible mechanisms of action. RIR caused a significant injury to RGCs and an obvious impairment of the inner retina functions, which could be seen from flash electroretinogram and flash visual evoked potential recordings. RIR also increased the expression of the apoptotic protein Bax while decreasing the expression of Bcl-2 and the phosphorylation of protein kinase B (Akt) in RGCs. Preinjection (i.m.) of NGF for 22 d reversed the injury induced by RIR and ameliorated the inner retina functions. NGF also reduced the expression of Bax and reversed the reduction of Bcl-2 and the phosphorylated Akt induced by RIR. These results indicate that NGF produces a neuroprotective effect on RGCs against RIR injury and the protective effect of NGF is mainly mediated by the PI-3K/Akt signaling pathway

Characterization of intracellular translocation of Forkhead transcription factor O (FoxO) members induced by NGF in PC12 cells

Nuclear translocation of Forkhead transcription factors of the O class (FoxOs) is important for the action of growth factors. However it is not known if all members of the FOXO family have the same translocation properties. We examined the effects of nerve growth factor (NGF) on nuclear/cytoplasmic shuttling of FoxO1, FoxO3a and FoxO6 in PC12 cells and determined their translocation kinetics. Our data demonstrated that NGF could induce the nuclear exclusion of FoxO1-GFP and FoxO3a-GFP in PC12 cells with different properties, but had no effect on FoxO6-GFP's nuclear localization and FoxO6-GFP showed an exclusive nuclear localization. Translocation of FoxO1 and FoxO3a could be blocked by K252a and LY294002 but not by PD98059.Moreover, FoxO3a returned to cytoplasm at a higher rate than FoxO1 after NGF stimulation and it was more sensitive than FoxO1 to NGF stimulation

IGF-1 signaling via the PI3K/Akt pathway confers neuroprotection in human retinal pigment epithelial cells exposed to sodium nitroprusside insult

The pathological increase in the levels of the second messenger nitric oxide (NO) in the vitreous cavity and retina leads to injury and cell death of the retinal pigment epithelium (RPE) cells and eventually may contribute to the occurrence and development of diabetic retinopathy. In this study, we developed a cellular model of retinopathy using D407 cells (a human RPE cell line) exposed to sodium nitroprusside (SNP) and investigated the protective effect of the insulin-like growth factor-1 (IGF-1) towards this insult. Cell death and apoptosis were examined by the methyl thiazolyl tetrazolium assay and Hoechst staining, respectively. Specific inhibitors were used and phosphorylation of relevant signaling proteins was determined by Western blotting. SNP, in a concentration-dependent fashion, increased the production of reactive oxygen species (ROS) and lipid peroxidation process causing cell death by apoptosis of D407 cells. IGF-1, in a time- and dose-dependent manner, conferred protection towards SNP-mediated insult. Both phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase (MAPK) were activated by IGF-1 in relation to the protective effect. Blockade of the PI3K/Akt pathway abolished the protective effect of IGF-1 whereas inhibition of the MAPK pathway was ineffective. SNP decreased the phosphorylation of Akt in the cells while IGF-1 reversed this inhibitory effect. These results indicate that the protective effect of IGF-1 on D407 exposed to SNP insult is mediated by the PI3K/Akt pathway. This proposal may be exploited in the clinic to improve the viability of insulted retinal cells for maintaining physiological vision

Toxicity profile characteristics of novel androgen-deprivation therapy agents in patients with prostate cancer: a meta-analysis

<p><b>Background</b>: To investigate the toxicity profile characteristics of abiraterone acetate and enzalutamide to see if they are of critical clinical value.</p> <p><b>Methods</b>: Prospective studies were identified by searching the PubMed, EMBASE, Cochrane Library, and American Society of Clinical Oncology Meeting abstracts. Randomized clinical trials that evaluate abiraterone acetate or enzalutamide in patients with prostate cancer were included. The risk ratio (RR) of adverse events (AEs) was calculated for each trial along with appropriate 95% CI using fixed- or random-effects methods.</p> <p><b>Results</b>: Ten studies (5 abiraterone acetate, and 5 enzalutamide studies) were included in the meta-analysis. Use of abiraterone acetate was associated with an increased risk of all-grade adverse effects (RR = 1.01, 95% CI: 1.01–1.02) and high-grade adverse effects (RR = 1.29, 95% CI: 1.15–1.45). Also, there was a significantly higher incidence of some individual adverse effects (e.g. liver-function test abnormalities, arthralgia, cardiac adverse effects, diarrhea, oedema, hypertension and hypokalemia). Treatment with enzalutamide did not increase the risk of all-grade adverse effects and high-grade adverse effects, but there was a significantly higher incidence of some individual adverse effects (e.g. back pain, fatigue, hot flush and hypertension).</p> <p><b>Conclusions</b>: Both abiraterone acetate and enzalutamide have toxicity profile characteristics that need to be recognized. Understanding the toxicity profile characteristics of both drugs could promote decision making in clinical use.</p