title: Sexual receptivity is reduced in the female mu-opioid receptor knockout mouse.
abstract: Activation of mu-opioid receptors is critical to steroid regulation of female sexual behavior, lordosis, in rodents. Estrogen treatment activates mu-opioid receptors in the medial preoptic area inhibiting lordosis, but ultimately appears important for progesterone facilitation of lordosis. We investigated the role of mu-opioid receptors in the expression of sexual receptivity in mice lacking mu-opioid receptors. Although estrogen and progesterone facilitated lordosis in mu-opioid receptor knockout mice, they exhibited deficits in lordosis quotient and score compared with wild-type females, indicating reduced sexual receptivity. In contrast, wild-type and mu-opioid receptor knockout female mice did not differ in either active or passive avoidance of the male. These data are most consistent with the hypothesis that mu-opioid receptor activation is necessary for estrogen and progesterone to maximally facilitate lordosis.
authors.affiliation: Department of Neurobiology, David Geffen School of Medicine, University of California at Los Angeles, USA. sinchak@cns.umass.edu
authors.forename: Kevin
authors.initials: K
authors.lastname: Sinchak
authors.forename: Kamyar
authors.initials: K
authors.lastname: Shahedi
authors.forename: Phoebe
authors.initials: P
authors.lastname: Dewing
authors.forename: Paul
authors.initials: P
authors.lastname: Micevych
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005091:Exons / Q000235:genetics; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D011187:Posture; D011374:Progesterone / Q000494:pharmacology; D017450:Receptors, Opioid, mu / Q000235:genetics* / Q000502:physiology*; D012726:Sexual Behavior, Animal / Q000502:physiology*
chemical_list: D017450:Receptors, Opioid, mu; D011374:Progesterone; D004958:Estradiol