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It has been reported that intraventricular administration of the melanocortin 4 receptor (MC4-R) agonist MT II and antagonist SHU9119 alter food intake. We found that MT II and SHU9119 have extremely potent effects on feeding when injected in the paraventricular nucleus (PVN), a site where MC4-R gene expression is very high. Our finding provides direct(More)
It has been suggested that opioids modify food intake by enhancing palatability. In the present series of studies we evaluated the effect of naloxone on food intake of a preferred food (chocolate chip cookies), normal rat chow, and an "aversive" food (high fiber chow). We found that naloxone decreased 18- and 48-h deprivation-induced intake of chocolate(More)
Differential effects of neuropeptide Y (NPY) and mu-opioid DAMGO on 'palatability' vs. 'energy'. A variety of studies suggest that NPY is an important manager of energy metabolism. In contrast, the opioid peptides appear to influence the 'rewarding' aspects of feeding. In the current study, we stimulated feeding by injecting NPY (110 pmol) or the mu-opioid(More)
The paraventricular nucleus of the hypothalamus (PVN) and the central nucleus of the amygdala (CNA) are two forebrain structures which are important in regulation of ingestive behavior. DAMGO is one of the most reliable and potent mu-selective opioid ligands that increases feeding in both of these brain nuclei. Administration of naloxone, an opioid(More)
The central nucleus of the amygdala (CNA) and the nucleus of the solitary tract (NTS) are important in the regulation of ingestive behavior. We evaluated whether opioid-opioid signaling between the CNA and rostral NTS (rNTS) affect feeding behavior. To test this, rats were doubly cannulated with one cannula placed in the rNTS and one cannula in the CNA,(More)
We measured the influence of diet composition on hypothalamic neuropeptide Y (NPY) message and brown fat uncoupling protein (UCP) mRNA using different diets. Sprague-Dawley rats ate ad libitum either chow, a high-carbohydrate (HC), an intermediate-carbohydrate (IHC), a high-fat (HF), or an intermediate-fat (IHF) diet, all with equal protein content(More)
Ghrelin is a 28 amino-acid peptide that has been shown to induce positive energy balance when administered both peripherally and centrally. This effect appears to occur by increasing food intake and by reducing fat utilization. Ghrelin injected into the PVN increases food intake dose-dependently. The NPY receptor has been implicated in the orexigenic effect(More)
MT II, agonist for MC3/4-Rs, inhibited Ghrelin's orexigenic effect in the paraventricular nucleus of the hypothalamus (PVN). To further investigate the role of the melanocortin system as mediator of ghrelin's orexigenic actions, we explored the involvement of AgRP in Ghrelin's orexigenic effect by testing the effect on food intake after their(More)
alpha-Melanocyte-stimulating hormone (alpha-MSH) appears to play a tonic inhibitory role in feeding and energy storage. MTII, a specific synthetic MC3-R/MC4-R agonist, has similar effects on feeding in rats. The current studies demonstrate that PVN administration of alpha-MSH or MTII decreases nocturnal and NPY-stimulated food intake without causing(More)
Agouti-related protein (Agrp) is an endogenous melanocortin-4 receptor antagonist implicated in the regulation of food intake. Effects of Agrp on feeding under varying conditions were investigated. Agrp (10 to 100 pmol) was injected into the hypothalamic paraventricular nucleus of satiated (a.m. and p.m. injections) and food-deprived rats, or was(More)