title: Adeno-associated virus-mediated knockdown of melanocortin-4 receptor in the paraventricular nucleus of the hypothalamus promotes high-fat diet-induced hyperphagia and obesity.
abstract: Pharmacological and genetic studies have suggested that melanocortin-4 receptor (MC4R) signaling in the paraventricular nucleus of hypothalamus (PVN) regulates appetite and energy balance. However, the specific role of MC4R signaling in PVN neurons in these processes remains to be further elucidated in normally developed animals. In the present study, we employed RNA interference to determine whether MC4R knockdown in the PVN modulates food intake and body weight in adult rats. Adeno-associated viral (AAV) vectors encoding short hairpin RNAs targeting MC4R (AAV-shRNA-MC4R) were generated to induce MC4R knockdown in the PVN. By in situ hybridization, we detected a high-level expression of Dicer, a key enzyme required for shRNA-mediated gene silencing, along the entire rostrocaudal extent of the PVN. Bilateral injection of AAV-shRNA-MC4R vectors into the PVN of the adult rat resulted in significant and specific reduction of MC4R mRNA expression. Animals with MC4R knockdown exhibited an increase in food intake and excessive body weight gain when exposed to a high-fat diet. Our results provide evidence that AAV-mediated silencing of MC4R on PVN neurons promotes hyperphagia and obesity in response to the dietary challenge in the adult animal.
authors.affiliation: Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229, USA.
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Garza
authors.forename: Chung Sub
authors.initials: CS
authors.lastname: Kim
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Xin-Yun
authors.initials: XY
authors.lastname: Lu
mesh_terms: D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000502:physiology; D000229:Dependovirus / Q000235:genetics*; D004041:Dietary Fats / Q000008:administration & dosage*; D020868:Gene Silencing; D006801:Humans; D006963:Hyperphagia / Q000209:etiology*; D008297:Male; D009765:Obesity / Q000209:etiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics / Q000502:physiology*; D043244:Ribonuclease III / Q000235:genetics; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology
chemical_list: D004041:Dietary Fats; D044105:Receptor, Melanocortin, Type 4; D013973:Thyrotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; D043244:Ribonuclease III