title: Blockade of endogenous GRF at dark onset selectively suppresses protein intake.
abstract: This study examined whether endogenous central GRF activity contributes to the increase in macronutrient intake shown by rats at dark onset. Animals were habituated to two diets: carbohydrate-fat and protein-fat. Antiserum raised against GRF (aGRF; 1% and 10% solutions) was microinjected into the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) at dark onset, and macronutrient intake was determined at 1, 2, and 4 h postinjection. aGRF blocked the increase in protein intake normally seen at dark onset, but had no effect on carbohydrate intake. These findings suggest that endogenous GRF activity in the SCN/MPOA region of the brain contributes to the circadian and nutritional organization of food intake.
authors.affiliation: Department of Psychology, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: P R
authors.initials: PR
authors.lastname: Dickson
authors.forename: D
authors.initials: D
authors.lastname: Feifel
authors.forename: F J
authors.initials: FJ
authors.lastname: Vaccarino
mesh_terms: D000821:Animal Feed; D000818:Animals; D002241:Carbohydrates / Q000008:administration & dosage / Q000502:physiology; D002940:Circadian Rhythm; D003624:Darkness; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000502:physiology; D008297:Male; D011506:Proteins / Q000008:administration & dosage* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002241:Carbohydrates; D011506:Proteins; D013007:Growth Hormone-Releasing Hormone