Glucocorticoid Effects on the Programming of AT1b Angiotensin Receptor Gene Methylation and Expression in the Rat

Adverse events in pregnancy may ‘programme’ offspring for the later development of cardiovascular disease and hypertension. Previously, using a rodent model of programmed hypertension we have demonstrated the role of the renin-angiotensin system in this process. More recently we showed that a maternal low protein diet resulted in undermethylation of the At1b angiotensin receptor promoter and the early overexpression of this gene in the adrenal of offspring. Here, we investigate the hypothesis that maternal glucocorticoid modulates this effect on fetal DNA methylation and gene expression. We investigated whether treatment of rat dams with the 11β-hydroxylase inhibitor metyrapone, could prevent the epigenetic and gene expression changes we observed. Offspring of mothers subjected to a low protein diet in pregnancy showed reduced adrenal Agtr1b methylation and increased adrenal gene expression as we observed previously. Treatment of mothers with metyrapone for the first 14 days of pregnancy reversed these changes and prevented the appearance of hypertension in the offspring at 4 weeks of age. As a control for non-specific effects of programmed hypertension we studied offspring of mothers treated with dexamethasone from day 15 of pregnancy and showed that, whilst they had raised blood pressure, they failed to show any evidence of Agtr1b methylation or increase in gene expression. We conclude that maternal glucocorticoid in early pregnancy may induce changes in methylation and expression of the Agtr1b gene as these are clearly reversed by an 11 beta-hydroxylase inhibitor. However in later pregnancy a converse effect with dexamethasone could not be demonstrated and this may reflect either an alternative mechanism of this glucocorticoid or a stage-specific influence

QRFP induces aldosterone production via PKC and T-type calcium channel-mediated pathways in human adrenocortical cells : evidence for a novel role of GPR 103

Hormonal regulation of adrenal function occurs primarily through activation of GPCRs. GPCRs are central to many of the body's endocrine and neurotransmitter pathways. Recently, it was shown that activation of GPR103 by its ligand QRFP induced feeding, locomotor activity, and metabolic rate, and QRFP is bioactive in adipose tissue of obese individuals. Given that the adrenal gland is a pivotal organ for energy balance and homeostasis, we hypothesized that GPR103 and QRFP are involved in steroidogenic responses. Using qRT-PCR and immunohistochemistry, we mapped both GPR103 and QRFP in human fetal and adult adrenal gland as well as rat adrenals. Both were primarily localized in the adrenal cortex but not in the medulla. Activation of GPR103 in human adrenocortical H295R cells led to a decrease in forskolin-increased cAMP and an increase of intracellular Ca(2+) levels. In addition, treatment of H295R cells with QRFP induced aldosterone and cortisol secretion as measured by ELISA. These increases were accompanied by increased expression and activity of StAR, CYB11B1, and CYP11B2 as assessed by qRT-PCR and luciferase reporter assay, respectively. Using specific inhibitors, we also demonstrated that aldosterone induction involves MAPK, PKC, and/or T-type Ca(2+) channel-dependent pathways. These novel data demonstrate that QRFP induces adrenal steroidogenesis in vitro by regulating key steroidogenic enzymes involving MAPK/PKC and Ca(2+) signaling pathways

Programming effects of short prenatal exposure to cortisol

Recent studies have linked fetal exposure to a suboptimal intrauterine environment with adult hypertension. The aims of this study were twofold: 1) to see whether cortisol treatment administered to the ewe for 2 days at 27 days of gestation (term ~150 days) resulted in high blood pressure in offspring; 2) to study the effect of the same treatment on gene expression in the brain at 130 days of gestation and in lambs at 2 months of age. Mean arterial pressure was significantly higher in the adult female and male offspring of sheep treated with cortisol than in the control group (females: 89±2 mmHg vs. 81±2;

The LepR-mediated leptin transport across brain barriers controls food reward

Objective: Leptin is a key hormone in the control of appetite and body weight. Predominantly produced by white adipose tissue, it acts on the brain to inhibit homeostatic feeding and food reward. Leptin has free access to circumventricular organs, such as the median eminence, but entry into other brain centers is restricted by the blood–brain and blood–CSF barriers. So far, it is unknown for which of its central effects leptin has to penetrate brain barriers. In addition, the mechanisms mediating the transport across barriers are unclear although high expression in brain barriers suggests an important role of the leptin receptor (LepR). Methods: We selectively deleted LepR in brain endothelial and epithelial cells of mice (LepRbeKO). The expression of LepR in fenestrated vessels of the periphery and the median eminence as well as in tanycytes was not affected. Results: Perfusion studies showed that leptin uptake by the brain depended on LepR in brain barriers. When being fed with a rewarding high-fat diet LepRbeKO mice gained more body weight than controls. The aggravated obesity of LepRbeKO mice was due to hyperphagia and a higher sensitivity to food reward. Conclusions: The LepR-mediated transport of leptin across brain barriers in endothelial cells lining microvessels and in epithelial cells of the choroid plexus controls food reward but is apparently not involved in homeostatic control of feeding

Nesfatin-1 decreases the motivational and rewarding value of food

Homeostatic and hedonic pathways distinctly interact to control food intake. Dysregulations of circuitries controlling hedonic feeding may disrupt homeostatic mechanisms and lead to eating disorders. The anorexigenic peptides nucleobindin-2 (NUCB2)/nesfatin-1 may be involved in the interaction of these pathways. The endogenous levels of this peptide are regulated by the feeding state, with reduced levels following fasting and normalized by refeeding. The fasting state is associated with biochemical and behavioral adaptations ultimately leading to enhanced sensitization of reward circuitries towards food reward. Although NUCB2/nesfatin-1 is expressed in reward-related brain areas, its role in regulating motivation and preference for nutrients has not yet been investigated. We here report that both dopamine and GABA neurons express NUCB2/nesfatin-1 in the VTA. Ex vivo electrophysiological recordings show that nesfatin-1 hyperpolarizes dopamine, but not GABA, neurons of the VTA by inducing an outward potassium current. In vivo, central administration of nesfatin-1 reduces motivation for food reward in a high-effort condition, sucrose intake and preference. We next adopted a 2-bottle choice procedure, whereby the reward value of sucrose was compared with that of a reference stimulus (sucralose + optogenetic stimulation of VTA dopamine neurons) and found that nesfatin-1 fully abolishes the fasting-induced increase in the reward value of sucrose. These findings indicate that nesfatin-1 reduces energy intake by negatively modulating dopaminergic neuron activity and, in turn, hedonic aspects of food intake. Since nesfatin-1´s actions are preserved in conditions of leptin resistance, the present findings render the NUCB2/nesfatin-1 system an appealing target for the development of novel therapeutical treatments towards obesity