TY - JOUR
T1 - Morphine suppresses the ovarian steroid hormone-dependent lordosis response of female guinea pigs
T2 - Reversal by naloxone but not clonidine
AU - Nock, Bruce
AU - Cicero, Theodore J.
N1 - Funding Information:
This research was supported in part by the McDonnell Center for Studies of Higher Brain Function, WashingtonU niversity School of Medicine (St. Louis, MO) and by Grants DA-03833a nd DA-05816f rom the National Institute on Drug Abuse and AA-03539 and AA-07144 from the National Institute on Alcohol Abuse and Alcoholism. T.J.C. is a recipiento f ResearchS cientistA ward DA-OOtJ95fr om the National Instituteo n Drug Abuse. We thank Mr. Atul Rajpara for his technical assistance.
PY - 1991/3
Y1 - 1991/3
N2 - The opiate agonist morphine caused a dose- and time-dependent suppression of lordosis responding in ovariectomized guinea pigs treated with estradiol-17β and progesterone. The suppression of lordosis by morphine appears to be mediated by opiate receptors since the opiate antagonist naloxone blocked its effects both in terms of the percentage of animals showing lordosis and the duration of individual responses. Naloxone, when given alone, did not affect lordosis responding in estradiol-17β + progesterone-primed animals and did not induce lordosis in animals primed with estradiol-17β alone. Thus, endogenous opioids might not tonically inhibit lordosis under the physiological conditions examined. The α-noradrenergic agonist clonidine did not reverse the effects of morphine on lordosis. Thus, the inhibitory effects of morphine on this behavior might be independent of its presynaptic effects on norepinephrine release in brain.
AB - The opiate agonist morphine caused a dose- and time-dependent suppression of lordosis responding in ovariectomized guinea pigs treated with estradiol-17β and progesterone. The suppression of lordosis by morphine appears to be mediated by opiate receptors since the opiate antagonist naloxone blocked its effects both in terms of the percentage of animals showing lordosis and the duration of individual responses. Naloxone, when given alone, did not affect lordosis responding in estradiol-17β + progesterone-primed animals and did not induce lordosis in animals primed with estradiol-17β alone. Thus, endogenous opioids might not tonically inhibit lordosis under the physiological conditions examined. The α-noradrenergic agonist clonidine did not reverse the effects of morphine on lordosis. Thus, the inhibitory effects of morphine on this behavior might be independent of its presynaptic effects on norepinephrine release in brain.
UR - http://www.scopus.com/inward/record.url?scp=0025972193&partnerID=8YFLogxK
U2 - 10.1016/0018-506X(91)90037-I
DO - 10.1016/0018-506X(91)90037-I
M3 - Article
C2 - 1646154
AN - SCOPUS:0025972193
SN - 0018-506X
VL - 25
SP - 29
EP - 37
JO - Hormones and Behavior
JF - Hormones and Behavior
IS - 1
ER -