Actions of repeated injections of LSD and apomorphine on the copulatory response of female rats.
LSD, a serotonin receptor stimulating agent, inhibits copulatory behavior (lordosis response) in the ovariectomized and estrogen + progesterone treated female rat. The same effect is obtained by apomorphine, a dopamine receptor stimulating compounds. The lordosis has been shown to be dependent on serotonin, but also dopamine has been implicated in its mediation. Tolerance develops to certain responses after repeated injections of LSD and in the present study the influence of apomorphine and LSD was compared, when given in repeated doses. Possible cross-tolerance between the two compounds was also tested on the frequency of lordosis responding in ovariectomized and hormone treated female rats. Tolerance to LSD develops over seven days, while the suppressing influence of apomorphine on lordosis in seven repeated doses is not significantly altered from that of a single dose. No cross-tolerance was observed on the lordosis response with either order of treatments. Repeated doses of LSD did not influence locomotor activity differently from a single dose, while repeated doses of apomorphine enhanced this response in comparison with the effect of an acute dose. These results indicate differential sensitivity to the repeated treatments and further support an interpretation of the LSD effects on lordosis responding to be primarily on serotonergic rather than dopaminergic receptors.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D002369:Castration; D003307:Copulation / Q000187:drug effects*; D004347:Drug Interactions; D004361:Drug Tolerance; D004958:Estradiol / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D008238:Lysergic Acid Diethylamide / Q000008:administration & dosage / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D011374:Progesterone; D004958:Estradiol; D008238:Lysergic Acid Diethylamide; D001058:Apomorphine