ABSTRACT
The effects of the muscarinic antagonist scopolamine on lordosis, solicitation, pacing, approach, attractivity, and activity were evaluated in ovariectomized rats brought into sexual receptivity with estrogen and progesterone. Systemic (1 mg/rat) or intraventricular (10 micrograms bilaterally) administration of scopolamine significantly reduced the incidence of lordosis and solicitation behaviors and disrupted typical pacing of sexual contacts with a stimulus male. In addition, females avoided contact with a stimulus male, but not a stimulus female, following intraventricular infusion of scopolamine. The levels of general activity and frequencies of sexual contacts were similar in females treated intraventricularly with scopolamine and vehicle solutions. Consequently, scopolamine disrupted various components of sexual behavior, including lordosis, solicitation, pacing, and approach, without altering female attractivity or general activity.
Subject(s)
Muscarinic Antagonists , Scopolamine/pharmacology , Sexual Behavior, Animal/drug effects , Animals , Brain/drug effects , Brain/physiology , Estradiol/pharmacology , Female , Libido/drug effects , Libido/physiology , Male , Motor Activity/drug effects , Motor Activity/physiology , Ovariectomy , Progesterone/pharmacology , Rats , Receptors, Muscarinic/physiology , Sexual Behavior, Animal/physiology , Social EnvironmentABSTRACT
The effect of cholinergic manipulations on sexual behavior in female hamsters was determined in a series of experiments. The cholinergic receptor antagonist, scopolamine, reduced total lordosis duration following systemic (1 mg/kg) or intraventricular (10 and 20 micrograms bilaterally) administration to ovariectomized hamsters primed with estrogen and progesterone. The inhibitory effect of scopolamine on lordosis occurred within 15 min after either treatment route and persisted at 2 hr after systemic administration. Intraventricular administration of the acetylcholinesterase inhibitor, physostigmine (10 micrograms bilaterally), activated lordosis of short duration in ovariectomized hamsters primed only with estrogen. These results indicate that the cholinergic system plays a facilitative role in the regulation of sexual behavior in female hamsters similar to that demonstrated previously in female rats. The activational effect of cholinergic neurotransmission on female sexual behavior may be a neural mechanism common to a number of mammalian species.
