title: Testosterone modulation of reproductive indices vs. morphine antinociception in male rats.
abstract: The purpose of this study was to determine whether testosterone (T) concurrently modulates reproductive and nociceptive systems in the adult male. Male Sprague-Dawley rats were orchidectomized, and then 28 days later implanted with capsules containing T or nothing (blanks). After 2, 7, 14 or 28 days' exposure to T-filled or blank capsules, rats were tested for male sexual and nociceptive behaviors in a counter-balanced design. As the duration of T exposure lengthened, the percentage of rats showing male sexual behaviors and the weights of steroid-sensitive organs systematically increased, and latencies to show sexual behaviors decreased. T treatment did not affect basal nociception on either the hotplate or tail withdrawal tests, but significantly increased morphine's antinociceptive potency on the tail withdrawal test -- however, this effect was small, and independent of duration of T exposure. Thus, T treatment that altered male sexual behavior and reproductive physiology in a systematic, duration-dependent manner did not similarly alter basal nociception or morphine antinociception. These findings suggest that in adult male rats, although T may modulate both male sexual behaviors and opioid antinociceptive sensitivity, these T effects do not occur in concert.
authors.affiliation: Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA.
authors.forename: Jean E
authors.initials: JE
authors.lastname: Sumner
authors.forename: Catherine
authors.initials: C
authors.lastname: Ulibarri
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Craft
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D000701:Analgesics, Opioid; D013739:Testosterone; D009020:Morphine