Behavioral specificity of beta-endorphin suppression of sexual behavior: differential receptor antagonism.
Open field behavior was observed in conjunction with mating behavior to discern whether the effect of intraventricular (ICV) beta-endorphin (beta-END) on sexual behavior may be secondary to akinesia. Three groups of ovariectomized, estrogen-progesterone-primed rats each received counterbalanced treatments of saline ICV, 2 micrograms beta-END ICV, or 2 micrograms beta-END ICV in combination with a selective opioid receptor antagonist. Receptive behavior (lordosis) and proceptive behaviors (presentation and ear wiggling) were consistently suppressed by beta-END, while ambulation was unaffected. Rearing and grooming were generally decreased, although this effect was statistically significant in only one experiment. Pretreatment with the mu-1 antagonist naloxazone (50 mg/kg intravenously) reversed the effects of beta-END on all behaviors tested. The delta receptor antagonist ICI-154,129 (12.5 and 50 micrograms ICV) only partially reversed the sexual effects of beta-END but completely reversed the open field effects. It is concluded that the suppressive effect of beta-END on sexual behavior, while not behaviorally specific, is not secondary to opioid-induced akinesia.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D009270:Naloxone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D001615:beta-Endorphin
D004723:Endorphins; D004967:Estrogens; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009270:Naloxone; D011374:Progesterone; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; C024224:naloxazone; C036405:ICI 154129