Glucagon-Like Peptide-1 (GLP-1) and 5-Hydroxytryptamine 2c (5-HT) Receptor Agonists in the Ventral Tegmental Area (VTA) Inhibit Ghrelin-Stimulated Appetitive Reward.

Current literature indicates that the orexigenic peptide ghrelin increases appetitive motivation via signaling in the mesolimbic reward system. Another gastric peptide, glucagon-like peptide-1 (GLP-1), and the neurotransmitter 5-hydroxytryptamine (5-HT), are both known to suppress operant responding for food by acting on key mesolimbic nuclei, including the ventral tegmental area (VTA). In order to investigate the interaction effects of ghrelin, GLP-1, and 5-HT within the VTA, we measured operant responding for sucrose pellets after the administration of ghrelin, the GLP-1 receptor agonist exendin-4 (Ex-4), and the 5-HT receptor agonist Ro60-0175 in male Sprague-Dawley rats.

Impact of [d-Lys(3)]-GHRP-6 and feeding status on hypothalamic ghrelin-induced stress activation.

Ghrelin administration directly into hypothalamic nuclei, including the arcuate nucleus (ArcN) and the paraventricular nucleus (PVN), alters the expression of stress-related behaviors. In the present study we investigated the effect of feeding status on the ability of ghrelin to induce stress and anxiogenesis. Adult male Sprague Dawley rats were implanted with guide cannula targeting either the ArcN or PVN.

Ghrelin alters the stimulatory effect of cocaine on ethanol intake following mesolimbic or systemic administration.

Emerging evidence suggests that ghrelinergic and dopaminergic signaling interact in the neural control of motivation and ethanol reward. To further investigate a possible interaction between these two neurochemical systems, we examined the impact of ghrelin, cocaine and combined injections of ghrelin with cocaine, on voluntary ethanol intake. Male Sprague-Dawley rats were habituated to an 8% ethanol solution until intakes stabilized.