title: The stimulation of central kappa opioid receptors decreases male sexual behavior and locomotor activity.
abstract: Systemic injections of the kappa (kappa) opioid receptor agonist U-50,488H decreased male sexual behavior, locomotor activity, body temperature and bodily grooming, and induced body flattening. The U-50,488H-induced inhibitions of male sexual behavior were prevented by systemic injections of naloxone and by intra-cranial injections of the kappa opioid antagonist nor-binaltorphimine (NBNI). Injections of NBNI to either the ventral tegmental area (VTA) or the nucleus accumbens septi (NAS) increased female-directed behavior, and prevented the U-50,488H-induced decreases in female-directed behavior. Intra-VTA NBNI prevented U-50,488H-induced decreases in the mean number of ejaculations, intra-NAS NBNI prevented U-50,488H-induced increases in copulation latencies. Intra-medial preoptic area (mPOA) injections of NBNI increased female-directed behavior, and attenuated U-50,488H-induced decreases in female-directed behavior as well as U-50,488H-induced increases in both copulation and ejaculation latencies. Injections of NBNI dorsal to the mPOA were ineffective. Two of 26 days following the central injection of NBNI, systemic injections of U-50,488H remained behaviorally ineffective, leaving both sexual behavior and locomotor activity undiminished. These results suggest that the stimulation of central kappa opioid receptors inhibits sexual behavior in the male rat; perhaps endogenous kappa opioid agonists induce sexual refractory periods.
authors.affiliation: Department of Psychology, Concordia University, Montréal, Que., Canada.
authors.forename: M
authors.initials: M
authors.lastname: Leyton
authors.forename: J
authors.initials: J
authors.lastname: Stewart
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D007267:Injections; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects; D011759:Pyrrolidines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000187:drug effects*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013681:Tegmentum Mesencephali / Q000187:drug effects
chemical_list: D011759:Pyrrolidines; D017473:Receptors, Opioid, kappa; D009270:Naloxone; C051844:norbinaltorphimine; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer