Hyperandrogenemia predisposes an organism toward developing impaired insulin sensitivity. The aim of our study was to evaluate endocrine and metabolic effects during early allostasis induced by a fructose-rich diet (FRD) in normal (control; CT) and neonatal-androgenized (testosterone propionate; TP) female adult rats. CT and TP rats were fed either a normal diet (ND) or an FRD for 3 weeks immediately before the day of study, which was at age 100 days. Energy intake, body weight (BW), parametrial (PM) fat characteristics, and endocrine/metabolic biomarkers were then evaluated. Daily energy intake was similar in CT and TP rats regardless of the differences in diet. When compared with CT-ND rats, the TP-ND rats were heavier, had larger PM fat, and were characterized by basal hypoadiponectinemia and enhanced plasma levels of non-esterified fatty acid (NEFA), plasminogen activator inhibitor-1 (PAI-1), and leptin. FRD-fed CT rats, when compared with CT-ND rats, had high plasma levels of NEFA, triglyceride (TG), PAI-1, leptin, and adiponectin. The TP-FRD rats, when compared with TP-ND rats, displayed enhanced leptinemia and triglyceridemia, and were hyperinsulinemic, with glucose intolerance. The PM fat taken from TP rats displayed increase in the size of adipocytes, decrease in adiponectin (protein/gene), and a greater abundance of the leptin gene. PM adipocyte response to insulin was impaired in CT-FRD, TP-ND, and TP-FRD rats. A very short duration of isocaloric FRD intake in TP rats induced severe metabolic dysfunction at the reproductive age. Our study supports the hypothesis that the early-androgenized female rat phenotype is highly susceptible to developing endocrine/metabolic dysfunction. In turn, these abnormalities enhance the risk of metabolic syndrome, obesity, type 2 diabetes, and cardiovascular disease.

Constitutive and ligand-dependent GHSR1a activity attenuates CaV2 current and hypothalamic GABA release through distinct mechanisms and signaling pathways.

An adverse endogenous environment during early life predisposes the organism to develop metabolic disorders. We evaluated the impact of intake of an iso-caloric fructose rich diet (FRD) by lactating mothers (LM) on several metabolic functions of their male offspring. On postnatal d 1, ad libitum eating, lactating Sprague-Dawley rats received either 10% F (wt/vol; FRD-LM) or tap water (controls, CTR-LM) to drink throughout lactation. Weaned male offspring were fed ad libitum a normal diet, and body weight (BW) and food intake were registered until experimentation (60 d of age). Basal circulating levels of metabolic markers were evaluated. Both iv glucose tolerance and hypothalamic leptin sensitivity tests were performed. The hypothalamus was dissected for isolation of total RNA and Western blot analysis. Retroperitoneal (RP) adipose tissue was dissected and either kept frozen for gene analysis or digested to isolate adipocytes or for histological studies. FRD rats showed increased BW and decreased hypothalamic sensitivity to exogenous leptin, enhanced food intake (between 49-60 d), and decreased hypothalamic expression of several anorexigenic signals. FRD rats developed increased insulin and leptin peripheral levels and decreased adiponectinemia; although FRD rats normally tolerated glucose excess, it was associated with enhanced insulin secretion. FRD RP adipocytes were enlarged and spontaneously released high leptin, although they were less sensitive to insulin-induced leptin release. Accordingly, RP fat leptin gene expression was high in FRD rats. Excessive fructose consumption by lactating mothers resulted in deep neuroendocrine-metabolic disorders of their male offspring, probably enhancing the susceptibility to develop overweight/obesity during adult life.

The stomach-derived hormone ghrelin mainly acts in the brain. Studies in mice have shown that the accessibility of ghrelin into the brain is limited and that it mainly takes place in some circumventricular organs, such as the median eminence. Notably, some known brain targets of ghrelin are distantly located from the circumventricular organs. Thus, we hypothesized that ghrelin could also access the brain via the blood-cerebrospinal fluid (CSF) barrier, which consists of the choroid plexus and the hypothalamic tanycytes. Using systemic injection of ghrelin or fluorescent-ghrelin in mice, we found that cells of the blood-CSF barrier internalize these molecules. In time-response studies, we found that peripherally injected fluorescent-ghrelin quickly reaches hypothalamic regions located in apposition to the median eminence and more slowly reaches the periventricular hypothalamic parenchyma, adjacent to the dorsal part of the third ventricle. Additionally, we found that CSF ghrelin levels increase after the systemic administration of ghrelin, and that central infusions of either an anti-ghrelin antibody, which immuno-neutralizes CSF ghrelin, or a scrambled version of ghrelin, which is also internalized by cells of the blood-CSF barrier, partially impair the orexigenic effect of peripherally injected ghrelin. Thus, current evidence suggests that the blood-CSF barrier can transport circulating ghrelin into the brain, and that the access of ghrelin into the CSF is required for its full orexigenic effect.

In rats, neonatal treatment with monosodium L-glutamate (MSG) induces several metabolic and neuroendocrine abnormalities, which result in hyperadiposity. No data exist, however, regarding neuroendocrine, immune and metabolic responses to acute endotoxemia in the MSG-damaged rat. We studied the consequences of MSG treatment during the acute phase response of inflammatory stress. Neonatal male rats were treated with MSG or vehicle (controls, CTR) and studied at age 90 days. Pituitary, adrenal, adipo-insular axis, immune, metabolic and gonadal functions were explored before and up to 5 h after single sub-lethal i.p. injection of bacterial lipopolysaccharide (LPS; 150 µg/kg). Our results showed that, during the acute phase response of inflammatory stress in MSG rats: (1) the corticotrope-adrenal, leptin, insulin and triglyceride responses were higher than in CTR rats, (2) pro-inflammatory (TNFα) cytokine response was impaired and anti-inflammatory (IL-10) cytokine response was normal, and (3) changes in peripheral estradiol and testosterone levels after LPS varied as in CTR rats. These data indicate that metabolic and neroendocrine-immune functions are altered in MSG-damaged rats. Our study also suggests that the enhanced corticotrope-corticoadrenal activity in MSG animals could be responsible, at least in part, for the immune and metabolic derangements characterizing hypothalamic obesity.

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Objective The octanoylated peptide hormone ghrelin regulates appetite and glycaemic control. Des-acyl ghrelin abolishes some effects of ghrelin, but does not bind to ghrelin receptor. LEAP2 is a novel ligand for ghrelin receptor that blocks the effects of ghrelin. Some evidences show that plasma levels of these peptides are altered in adults with obesity, but their levels in childhood obesity remain poorly studied. Therefore, the objective of this study was to assess fasting plasma levels of ghrelin, des-acyl ghrelin and LEAP2 in children with normoweight, overweight/obesity and their association with different anthropometric and metabolic variables. Design A total of 42 females and 40 males, ages 3–12 years old were enrolled as a cross-sectional cohort. Results Plasma levels of des-acyl ghrelin and LEAP2 (but not ghrelin) were lower and ghrelin/des-acyl ghrelin ratio was higher in children with overweight/obesity. Des-acyl ghrelin negatively correlated with age, BMI z-score, insulin and HOMA index, and the correlations were stronger in children with overweight/obesity. LEAP2 levels negatively correlated with BMI z-score. No gender differences were found. Conclusions Our findings suggest that ghrelin tone is increased in childhood obesity, due to a decrease on plasma levels of des-acyl ghrelin and LEAP2, and that des-acyl ghrelin is associated to insulin resistance, particularly in children with overweight/obesity.

The growth hormone secretagogue receptor (GHSR) is a G protein‐coupled receptor that is highly expressed in the central nervous system. GHSR acts as a receptor for ghrelin and for liver‐expressed antimicrobial peptide 2 (LEAP2), which blocks ghrelin‐evoked activity. GHSR also displays ligand‐independent activity, including a high constitutive activity that signals in the absence of ghrelin and is reduced by LEAP2. GHSR activity modulates a variety of food intake‐related behaviours, including binge eating. Previously, we reported that GHSR‐deficient mice daily and time‐limited exposed to a high‐fat (HF) diet display an attenuated binge‐like HF intake compared to wild‐type mice. In the present study, we aimed to determine whether ligand‐independent GHSR activity affects binge‐like HF intake in a 4‐day binge‐like eating protocol. We found that plasma levels of ghrelin and LEAP2 were not modified in mice exposed to this binge‐like eating protocol. Moreover, systemic administration of ghrelin or LEAP2 did not alter HF intake in our experimental conditions. Interestingly, we found that central administration of LEAP2 or K‐(D‐1‐Nal)‐FwLL‐NH2, which are both blockers of constitutive GHSR activity, reduced binge‐like HF intake, whereas central administration of ghrelin or the ghrelin‐evoked GHSR activity blockers [D‐Lys3]‐GHRP‐6 and JMV2959 did not modify binge‐like HF intake. Taken together, current data indicate that GHSR activity in the brain affects binge‐like HF intake in mice independently of plasma levels of ghrelin and LEAP2.