Search

Introduction: Ischemic stroke has high morbidity and mortality rates worldwide. Low oxygen (O2) levels detected in such conditions create a vulnerable environment for neural stem cells (NSC), altering neuronal function, and leading to neuronal injury or death. There are still no effective treatments for such consequences. This study investigates the molecular and functional effects of growth factors, namely, insulin-like growth factor 1 (IGF-I) and mechano growth factor (MGF), in NSC exposed to low O2 levels. Methods: An in vitro ischemia model was created by rat hippocampal NSC grown in culture that was exposed to varying oxygen levels, including 0%, 3%, and 20 % for the representation of anoxic, hypoxic, and normoxic conditions, respectively, during 24 h. NSC has investigated IGF-I, MGF, and HIF1-Alpha (HIF-1α) gene expressions by real-time reverse transcription polymerase chain reaction. The effects of external administration of growth factors (IGF-I and MGF) on NSC proliferation in such conditions were explored. Results: Increased IGF-I and MGF gene expressions were detected in the samples exposed to low O2. Anoxia was the highest stimulant for IGF-I and MGF gene expressions. Meanwhile, HIF1-α that encodes hypoxia-inducible factor-1α revealed downregulation in relative gene expression fold change with IGF-I application in all conditions, whereas MGF application upregulated its change in an anoxic environment. Furthermore, MGF-induced NSC had more proliferationmigration rate in all oxygen conditions. IGF-I induced significant NSC proliferation in 0% and 20% O2. Conclusion: These findings suggest that IGF-I and MGF expressions were increased to reduce the damage in NSC exposed to low oxygen, and exogenous MGF and IGF-I application increased NSC proliferation at the time of injury. The results might imply the role of exogenous MGF and IGF-I in the treatment of ischemia for relieving the effect of neuronal damage due to their neuroprotective and proliferative effects. [ABSTRACT FROM AUTHOR]

The mechanisms whereby insulin analogues may cause enhanced mitogenicity through activation of either the IR (insulin receptor) or the IGF-IR (insulin-like growth factor 1 receptor) are incompletely understood. We demonstrate that in L6 myoblasts expressing only IGF-IRs as well as in the same cells overexpressing the IR, IGF-I (insulin-like growth factor 1), insulin and X10 (AspB10 insulin) down-regulate the mRNA expression level of the cell cycle inhibitor cyclin G2, as measured by qRTPCR (quantitative reverse transcription-PCR), and induce cell growth measured by [6-³H]thymidine incorporation into DNA. Western blotting showed a marked down-regulation of cyclin G2 at the protein level in both cell lines. Overexpression of cyclin G2 in the two cell lines diminished the mitogenic effect of all three ligands. The use of specific inhibitors indicated that both the MAPK (mitogen-activated protein kinase) and the PI3K (phosphoinositide 3-kinase) pathways mediate the downregulation of Ccng2. The down-regulation of CCNG2 by the three ligands was also observed in other cell lines: MCF-7, HMEC, Saos-2, R- /IR and INS-1. These results indicate that regulation of cyclin G2 is a key mechanism whereby insulin, insulin analogues and IGF-I stimulate cell proliferation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Female Wistar rats were exposed to triptolide and microarrays were performed. [•] Triptolide altered insulin signaling pathway and glucose metabolism. [•] Triptolide altered cell cycle, increased oxidative stress and apoptosis. [•] Triptolide-induced hepatotoxicity in female rats involved glucocorticoid and IGF-1. [ABSTRACT FROM AUTHOR]

Abstract: Due to eutrophication, high environmental ammonia (HEA) has become a frequent problem in aquatic environments, especially in agricultural or densely populated areas. During certain periods, e.g. winter, feed deprivation may occur simultaneously in natural waters. Additionally, under such stressful circumstances, fish may be enforced to swim at a high speed in order to catch prey, avoid predators and so on. Consequently, fish need to cope with all these stressors by altering physiological processes which in turn are controlled by genes expression. Therefore, in the present study, ammonia toxicity was tested in function of nutrient status (fed versus starved) and swimming performance activity (routine versus exhaustive). Goldfish, a relatively tolerant cyprinid, were exposed to HEA (1mg/L; Flemish water quality guideline for surface water) for a period of 3h, 12h, 1 day, 4 days, 10 days, 21 days and 28 days and were either fed (2% body weight) or starved (kept unfed for 7 days prior to sampling). Results showed that the activity of Na+/K+-ATPase in the gills was stimulated by HEA and disturbance in ion balance was obvious with increases in plasma [Na+], [Cl−] and [Ca2+] after prolonged exposure. Additionally, osmoregulation and metabolism controlling hormones like cortisol and thyroid hormones (T3 and T4) were investigated to understand adaptive responses. The expression kinetics of growth, stress and osmo-regulatory representative genes such as Insulin-like growth factor 1 (IGF-I), growth hormone receptor (GHR), thyroid hormone receptor β (THRβ), prolactin receptor (PRLR), cortisol receptor (CR) and Na+/K+-ATPase α3 were examined. Overall effect of HEA was evident since Na+/K+-ATPase activity, plasma cortisol, Na+ and Ca2+ concentration, expression level of CR and Na+/K+-ATPase α3 mRNA in fed and starved fish were increased. On the contrary, transcript level of PRLR was reduced after 4 days of HEA; additionally T3 level and expression of GHR, IGF-I and THRβ genes were decreased following 10–21 days of HEA. Starvation, the additional challenge in the present study, significantly increased plasma cortisol level and CR transcript level under HEA compared to the fed exposed and control fish. Furthermore, a remarkable reduction in T3 and mRNA levels of THRβ, IGF-I and GHR genes was observed under starvation. The toxic effects in both feeding treatments were exacerbated when imposed to exhaustive swimming with more pronounced effects in starved fish. This confirms that starvation makes fish more vulnerable to external ammonia, especially during exercise. [Copyright &y& Elsevier]