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Effects of copulation on apomorphine-induced erection in rats
B D Sachs1, K Akasofu, S S McEldowney
1Department of Psychology, University of Connecticut, Storrs 06269-1020.
Pharmacology, Biochemistry, and Behavior
|June 1, 1994
Summary
Copulation significantly impacts drug-induced erections in male rats. Sexual satiety abolished apomorphine-induced erections, suggesting natural sexual activity influences erectile responses.
Area of Science:
- Neuroscience
- Animal Behavior
- Pharmacology
Background:
- Research on drug-induced erections often assumes relevance to natural copulation.
- The influence of prior sexual activity on drug-induced erectile responses is not well understood.
Purpose of the Study:
- To investigate how antecedent copulation affects apomorphine-induced penile erections in male rats.
- To determine if drug-induced erection research accurately reflects erectile regulation during copulation.
Main Methods:
- Male rats received subcutaneous injections of varying apomorphine doses (0-120 µg/kg).
- Subsequent experiments involved apomorphine administration after different sexual experiences: no female exposure, three intromissions, or sexual satiety.
- Erectile responses and yawning were measured.
Main Results:
- Apomorphine induced erections and yawning, with 60 µg/kg being optimal.
- Sexual satiety significantly reduced or abolished apomorphine-induced erections.
- While apomorphine's effects were not reliably altered by copulation in treated males, vehicle-treated males with prior copulation showed shorter erection latencies and more erections.
Conclusions:
- Copulation, particularly sexual satiety, can inhibit apomorphine-induced erections.
- Natural sexual activity can elicit erectile responses comparable to those induced by optimal apomorphine doses.
- Findings challenge the assumption that drug-induced erection studies directly inform the regulation of erection during copulation.