title: Estradiol promotes the rewarding effects of nicotine in female rats.
abstract: It is presently unclear whether ovarian hormones, such as estradiol (E2), promote the rewarding effects of nicotine in females. Thus, we compared extended access to nicotine intravenous self-administration (IVSA) in intact male, intact female, and OVX female rats (Study 1) as well as OVX females that received vehicle or E2 supplementation (Study 2). The E2 supplementation procedure involved a 4-day injection regimen involving 2 days of vehicle and 2 days of E2 administration. Two doses of E2 (25 or 250μg) were assessed in separate groups of OVX females in order to examine the dose-dependent effects of this hormone on the rewarding effects of nicotine. The rats were given 23-hour access to nicotine IVSA using an escalating dose regimen (0.015, 0.03, and 0.06mg/kg/0.1mL). Each dose was self-administered for 4 days with 3 intervening days of nicotine abstinence. The results revealed that intact females displayed higher levels of nicotine intake as compared to males. Also, intact females displayed higher levels of nicotine intake versus OVX females. Lastly, our results revealed that OVX rats that received E2 supplementation displayed a dose-dependent increase in nicotine intake as compared to OVX rats that received vehicle. Together, our results suggest that the rewarding effects of nicotine are enhanced in female rats via the presence of the ovarian hormone, E2.
authors.affiliation: Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 United States.
authors.forename: Rodolfo J
authors.initials: RJ
authors.lastname: Flores
authors.affiliation: Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 United States.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Pipkin
authors.affiliation: Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 United States.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Uribe
authors.affiliation: Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 United States.
authors.forename: Adriana
authors.initials: A
authors.lastname: Perez
authors.affiliation: Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 United States. Electronic address: lodell@utep.edu.
authors.forename: Laura E
authors.initials: LE
authors.lastname: O'Dell
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008297:Male; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000008:administration & dosage*; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D012646:Self Administration; D012727:Sex Characteristics
chemical_list: D018722:Nicotinic Agonists; D004958:Estradiol; D009538:Nicotine
keywords: Estradiol; Rat; Self-administration; Sex differences; Tobacco