title: The inhibitory effects of corncob bedding on sexual behavior in the ovariectomized Long-Evans rat treated with estradiol benzoate are overcome by male cues.
abstract: The mechanisms underlying the sensitization of sexual behaviors by repeated administration of estradiol benzoate (EB) to ovariectomized (OVX) rats are not well understood. Here we tested whether two housing conditions play a role. Sexual behavior in the female rat is dependent on the activation of ERα (estrogen receptor alpha) by estradiol. Corncob (CC) bedding has been reported to have adverse effects on the reproductive behavior and physiology of rats, and to disrupt ERα signaling in mice. In addition, some rodent behaviors are stimulated by olfactory stimuli and enhanced in the presence of estradiol. Upon arrival to the facilities OVX Long-Evans rats were housed on either Sani-Chips (SC) or CC in a room that housed only females (F) or males and females (M). Females were first given four sexual training sessions with 10 μg EB + 500 μg progesterone (P; administered 48 h and 4h prior to training, respectively), followed by a 2-week hormone washout period. Next, 10 μg EB was administered s.c. every 4 days, 48 h prior to each of 8 test sessions in a unilevel 4-hole pacing chamber. On the final training day (i.e., when primed with EB+P), no inhibitory effects of corncob bedding were found, however a facilitation of the lordosis quality occurred in SC/F. Although all groups appear to have sensitized to the repeated administration of EB, CC/F animals displayed fewer high quality lordosis magnitudes and hop/darts, and received fewer mounts and intromissions overall. They also had a lower lordosis quotient (LQ) on tests 2-4 although this effect disappeared by test 5. These results suggest that although CC may inhibit some components of female sexual behavior when primed with EB alone, cues from sexually vigorous males can overcome that inhibition. Moreover, they suggest that male cues can facilitate mechanisms of estradiol sensitization. We recommend that quality control studies be conducted at individual institutions to assess any impact of corncob bedding on animal physiology and behavior.
authors.affiliation: Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC H4B 1R6, Canada. Electronic address: sljones@live.concordia.ca.
authors.forename: Sherri Lee
authors.initials: SL
authors.lastname: Jones
authors.affiliation: Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC H4B 1R6, Canada.
authors.forename: R Alexandru
authors.initials: RA
authors.lastname: Antonie
authors.affiliation: Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, QC H4B 1R6, Canada.
authors.forename: James G
authors.initials: JG
authors.lastname: Pfaus
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects*; D003463:Cues; D004338:Drug Combinations; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D006799:Housing, Animal; D008297:Male; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D003313:Zea mays
chemical_list: D004338:Drug Combinations; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; C025370:estradiol benzoate, progesterone drug combination
keywords: Corncob; Estradiol sensitization; Housing; Rat; Sexual behavior