Search results for "Arcuate nucleus"

Food Intake Adaptation to Dietary Fat Involves PSA-Dependent Rewiring of the Arcuate Melanocortin System in Mice

2012

International audience; Hormones such as leptin and ghrelin can rapidly rewire hypothalamic feeding circuits when injected into rodent brains. These experimental manipulations suggest that the hypothalamus might reorganize continually in adulthood to integrate the metabolic status of the whole body. In this study, we examined whether hypothalamic plasticity occurs in naive animals according to their nutritional conditions. For this purpose, we fed mice with a short-term high-fat diet (HFD) and assessed brain remodeling through its molecular and functional signature. We found that HFD for 3 d rewired the hypothalamic arcuate nucleus, increasing the anorexigenic tone due to activated pro-opio…

Hypothalamic eIF2 alpha signaling regulates food intake

2014

International audience; The reversible phosphorylation of the a subunit of eukaryotic initiation factor 2 (eIF2 alpha) is a highly conserved signal implicated in the cellular adaptation to numerous stresses such as the one caused by amino acid limitation. In response to dietary amino acid deficiency, the brain-specific activation of the eIF2 alpha kinase GCN2 leads to food intake inhibition. We report here that GCN2 is rapidly activated in the mediobasal hypothalamus (MBH) after consumption of a leucine-deficient diet. Furthermore, knockdown of GCN2 in this particular area shows that MBH GCN2 activity controls the onset of the aversive response. Importantly, pharmacological experiments demo…

Insulin acts at different CNS sites to decrease acute sucrose intake and sucrose self-administration in rats.

2008

Findings from our laboratory and others have demonstrated that the hormone insulin has chronic effects within the CNS to regulate energy homeostasis and to decrease brain reward function. In this study, we compared the acute action of insulin to decrease intake of a palatable food in two different behavioral tasks—progressive ratios sucrose self-administration and mu opioid-stimulated sucrose feeding—when administered into several insulin-receptive sites of the CNS. We tested insulin efficacy within the medial hypothalamic arcuate (ARC) and paraventricular (PVN) nuclei, the nucleus accumbens, and the ventral tegmental area. Administration of insulin at a dose that has no chronic effect on …

Mating Increases Neuronal Tyrosine Hydroxylase Expression and Selectively Gates Transmission of Male Chemosensory Information in Female Mice

2013

Exposure to chemosensory signals from unfamiliar males can terminate pregnancy in recently mated female mice. The number of tyrosine hydroxylase-positive neurons in the main olfactory bulb has been found to increase following mating and has been implicated in preventing male-induced pregnancy block during the post-implantation period. In contrast, pre-implantation pregnancy block is mediated by the vomeronasal system, and is thought to be prevented by selective inhibition of the mate's pregnancy blocking chemosignals, at the level of the accessory olfactory bulb. The objectives of this study were firstly to identify the level of the vomeronasal pathway at which selective inhibition of the m…

Topography of somatostatin gene expression relative to molecular progenitor domains during ontogeny of the mouse hypothalamus

2010

The hypothalamus comprises alar, basal, and floor plate developmental compartments. Recent molecular data support a rostrocaudal subdivision into rostral (terminal) and caudal (peduncular) halves. In this context, the distribution of neuronal populations expressing somatostatin (Sst) mRNA was analyzed in the developing mouse hypothalamus, comparing with the expression pattern of the genes Orthopedia (Otp), Distal-less 5 (Dlx5), Sonic Hedgehog (Shh), and Nk2 homeobox 1 (Nkx2.1). At embryonic day 10.5 (E10.5), Sst mRNA was first detectable in the anterobasal nucleus, a Nkx2.1-, Shh-, and Otp-positive basal domain. By E13.5, nascent Sst expression was also related to two additional Otp-positiv…

Acute selective ablation of rat insulin promoter-expressing (RIP HER ) neurons defines their orexigenic nature

2012

Rat insulin promoter (RIP)-expressing neurons in the hypothalamus control body weight and energy homeostasis. However, genetic approaches to study the role of these neurons have been limited by the fact that RIP expression is predominantly found in pancreatic β-cells, which impedes selective targeting of neurons. To define the function of hypothalamic RIP-expressing neurons, we set out to acutely and selectively eliminate them via diphtheria toxin-mediated ablation. Therefore, the diphtheria toxin receptor transgene was specifically expressed upon RIP-specific Cre recombination using a RIP-Cre line first described by Herrera (RIP HER -Cre) [Herrera PL (2000) Development 127:2317–2322]. Usi…

2015

The melanocortin system is one of the most important neuronal pathways involved in the regulation of food intake and is probably the best characterized. Agouti-related peptide (AgRP) and proopiomelanocortin (POMC) expressing neurons located in the arcuate nucleus of the hypothalamus are the key elements of this system. These two neuronal populations are sensitive to circulating molecules and receive many excitatory and inhibitory inputs from various brain areas. According to sensory and metabolic information they integrate, these neurons control different aspects of feeding behavior and orchestrate autonomic responses aimed at maintaining energy homeostasis. Interestingly, composition and a…

Agouti-related peptide-expressing neurons are mandatory for feeding.

2005

Multiple hormones controlling energy homeostasis regulate the expression of neuropeptide Y (NPY) and agouti-related peptide (AgRP) in the arcuate nucleus of the hypothalamus. Nevertheless, inactivation of the genes encoding NPY and/or AgRP has no impact on food intake in mice. Here we demonstrate that induced selective ablation of AgRP-expressing neurons in adult mice results in acute reduction of feeding, demonstrating direct evidence for a critical role of these neurons in the regulation of energy homeostasis.