Differential regulation of hypothalamic neuropeptide Y hnRNA and mRNA during psychological stress and insulin-induced hypoglycemia
ABSTRACT Many signals reflecting energy balance and stress are integrated at the hypothalamic orexigenic NPY neurons. To determine transcriptional changes of the NPY gene in response to stress, we followed the time course and compared the expression of heteronuclear (hn)- and messenger (m)RNA levels by in situ hybridization histochemistry and by real time PCR in mice following insulin-induced hypoglycemia and restraint. Hypoglycemia in fasted mice resulted in a rapid increase of NPY hnRNA that peaked at 1h, declined thereafter by 2-4h after insulin injection and run parallel to that of NPY mRNA. Throughout the time course examined, NPY expressing cells in the medial basal hypothalamus remained overwhelmingly localized to the arcuate nucleus. Following restraint NPY mRNA slightly increased, however hnRNA levels decreased up to 2h, suggesting increased stability of mature NPY mRNA. These results highlight rapid changes and differential regulation of NPY expression in response to metabolic and stress challenges.
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ABSTRACT: Fluoxetine (FLX) is one of the most commonly detected pharmaceuticals in wastewater and bioaccumulates in wild-caught fish, especially in brain, liver and muscle tissues. Previous studies indicated that FLX is pharmacologically active in fish species exerting anorexigenic effects, but it is not clear whether waterborne FLX has any potential effects on regulating food intake and energy metabolism. In this study, we investigated the effect of two doses of FLX, an environmental concentration of 540 ng/L, and 100-times this concentration (54 μg/L), on feeding and key metabolic parameters in goldfish. Fish were exposed for a period of 28 days and changes in food intake and body mass were assessed. Pair-fed groups were maintained to discern primary FLX-induced effects from secondary metabolic responses induced by the decreased food intake. Additionally, an untreated control group and a fasted group were used to further compare physiological changes in the context of nutritional status of the animals. Significant decreases in food intake and weight gain were recorded in goldfish exposed to 54 μg/L FLX. Furthermore a significant decrease occurred in circulating glucose levels in the group exposed to 540 ng/L FLX. To elucidate potential mechanisms, we investigated gene expression of feeding neuropeptides in the neuroendocrine brain of goldfish as well as gene expression and enzymatic activity of glycolytic and gluconeogenetic enzymes in liver and muscle tissues. The results confirm brain gene expression patterns in line with potential anorexigenic effects in the hypothalamus, with increased expression in corticotropin-releasing factor (CRF) and decreased expression of neuropeptide Y (NPY). With respect to glucose metabolism, liver gene expression of the gluconeogenic enzyme fructose-1,6-bisphosphatase decreased and muscle hexokinase activity increased in fish exposed to 540 ng/L FLX. Overall, this study demonstrated anorectic properties of FLX at a dose of 54 μg/L FLX and moderate but significant effects on glucose metabolism in goldfish exposed to 540 ng/L FLX. Future studies investigating the importance of these changes in fish are warranted.Aquatic toxicology (Amsterdam, Netherlands) 10/2010; 100(1):128-37. DOI:10.1016/j.aquatox.2010.07.022 · 3.51 Impact Factor
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ABSTRACT: The cryptococcus-specific protein antiphagocytic protein 1 (App1) regulates Cryptococcus neoformans virulence by controlling macrophage-driven fungal phagocytosis. This is accomplished through complement receptors (CR), specifically CR3. When inhaled, C. neoformans can cause a life-threatening meningoencephalitis in immunocompromised patients. Because glucose starvation can significantly change the gene expression and virulence of C. neoformans and because App1 is critical for phagocytosis in the lung-a low-glucose environment-we investigated the role of glucose in App1 expression. We found that App1 was upregulated dramatically under low-glucose conditions, and it was upregulated when C. neoformans cells were incubated in bronchoalveolar lavage (BAL) fluid, serum, and cerebrospinal fluid, which are low-glucose environments. Characterization of App1's regulation based on mammalian lung physiology revealed that App1 is upregulated via both increases in transcription and increases in mRNA stability. Our data provide new insights regarding C. neoformans adaptations to low-glucose environments.Eukaryotic Cell 03/2011; 10(3):293-301. DOI:10.1128/EC.00252-10 · 3.18 Impact Factor
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ABSTRACT: BACKGROUND: Alcoholism is a heterogeneous disease, with subjects possibly differing both in the best measure that predicts their excess consumption and in their most effective pharmacotherapy. Two different measures, high novelty-induced activity and high-fat-induced triglycerides (TGs), are known to identify subgroups of animals prone to consuming higher amounts of ethanol (EtOH). The question investigated here is whether these subgroups are, in fact, similar in their neurochemical phenotype that may contribute to their overconsumption. METHODS: EtOH-naïve, Sprague-Dawley rats were subgrouped based on the 2 predictor measures of activity or TG levels, and then quantitative real-time polymerase chain reaction and digoxigenin-labeled in situ hybridization were used to measure their expression of hypothalamic peptides that affect EtOH intake. In additional subgroups subsequently trained to drink 9% EtOH, the opioid antagonist and alcoholism medication, naltrexone, was tested at a low dose (0.02 mg/kg, s.c.) to determine the rats' sensitivity to its effects. RESULTS: The 2 measures, while both effective in predicting amount of EtOH intake, were found to identify distinctive subgroups. Rats with high compared to low activity exhibited significantly greater expression of galanin and enkephalin in the paraventricular nucleus (PVN) and of orexin in the perifornical lateral hypothalamus (PFLH), but no difference in melanin-concentrating hormone in PFLH or neuropeptide Y in arcuate nucleus. This contrasts with rats having high TG, which exhibited greater expression only of PVN galanin, along with reduced PFLH orexin. The high-activity rats with elevated enkephalin, but not high-TG rats, were also unusually sensitive to naltrexone, which significantly reduced their alcohol intake. CONCLUSIONS: In addition to revealing differences in endogenous peptides and drug responsiveness in predicted high EtOH drinkers, this study demonstrates that these disturbances differ markedly between the 2 at-risk subgroups. This indicates that simple tests may be effective in identifying subjects most responsive to a specific pharmacotherapy.Alcoholism Clinical and Experimental Research 06/2012; 37. DOI:10.1111/j.1530-0277.2012.01858.x · 3.31 Impact Factor