title: Estradiol increases the anorexia associated with increased 5-HT(2C) receptor activation in ovariectomized rats.
abstract: Estradiol's inhibitory effect on food intake is mediated, in part, by its ability to increase the activity of meal-related signals, including serotonin (5-HT), which hastens satiation. The important role that postsynaptic 5-HT(2C) receptors play in mediating 5-HT's anorexigenic effect prompted us to investigate whether a regimen of acute estradiol treatment increases the anorexia associated with increased 5-HT(2C) receptor activation in ovariectomized (OVX) rats. We demonstrated that intraperitoneal and intracerebroventricular (i.c.v.) administration of low doses of the 5-HT(2C) receptor agonist meta-chlorophenylpiperazine (mCPP) decreased 1-h dark-phase food intake in estradiol-treated, but not oil-treated, OVX rats. During a longer feeding test, we demonstrated that i.c.v. administration of mCPP decreased 22-h food intake in oil-treated and, to a greater extent, estradiol-treated OVX rats. In a second study, we demonstrated that estradiol increased 5-HT(2C) receptor protein content in the caudal brainstem, but not hypothalamus, of OVX rats. We conclude that a physiologically-relevant regimen of acute estradiol treatment increases sensitivity to mCPP's anorexigenic effect. Our demonstration that this same regimen of estradiol treatment increases 5-HT(2C) receptor protein content in the caudal hindbrain of OVX rats provides a possible mechanism to explain our behavioral findings.
authors: Department of Psychology and program in Neuroscience, The Florida State University, Tallahassee, FL 32306-4301, USA.
authors: Heidi M
authors: HM
authors: Rivera
authors: Jessica
authors: J
authors: Santollo
authors: Larissa V
authors: LV
authors: Nikonova
authors: Lisa A
authors: LA
authors: Eckel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000855:Anorexia / Q000139:chemically induced*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004195:Disease Models, Animal; D004333:Drug Administration Routes; D004435:Eating / Q000187:drug effects; D004958:Estradiol / Q000009:adverse effects*; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D010052:Ovariectomy; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D044405:Receptor, Serotonin, 5-HT2C / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors
chemical_list: D004967:Estrogens; D010879:Piperazines; D044405:Receptor, Serotonin, 5-HT2C; D017366:Serotonin Receptor Agonists; D004958:Estradiol; C015068:1-(3-chlorophenyl)piperazine