| Abstract No.: | A-G1183 |
| Country: | Canada |
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| Title: | NALOXONE DISRUPTS THE INDUCTION OF PARTNER PREFERENCE BY PACED COPULATION IN MALE RATS |
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| Authors/Affiliations: | 1 Nafissa Ismail*; 1 Satoru Nakanishi; 1 James G. Pfaus;
1 CSBN/Psychology, Concordia University, Montreal, QC, Canada.
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| Content: | Objective: Although male rats are believed to show greater sexual arousal and mating preference for a novel female compared to a familiar one, we have shown that after repeated copulation to ejaculation with a female bearing a neutral odor in either bilevel chambers or pacing chambers bisected by a 1-hole divider, male rats display a conditioned ejaculatory preference for a sexually receptive female scented with the odor relative to an unscented receptive female. We have also shown that the conditioning occurs during the refractory period after ejaculation, a time when endogenous opioid activity is high. The aim of the present study was to examine the role of endogenous opioids in the development of the conditioned ejaculatory preference.
Materials and methods: Male Long-Evans rats were randomly assigned to one of two groups. One group was injected with the opioid receptor antagonist naloxone (5 mg/kg/ml) whereas the control group was injected with physiological saline, 5 min before each coplatory conditioning trial. Each male was given 10 copulatory trials with a Long Evans female scented with almond odor. Copulatory preferences were then examined in an open field where males had the choice to copulate with either the familiar almond-scented female or a novel unscented female. All males were drug-free prior to the final preference test.
Results: As in our previous studies, males in the control group ejaculated significantly more often with the scented female. In contrast, males that received naloxone during training failed to display a conditioned ejaculatory preference for the scented female. In fact, those males displayed a copulatory preference for the novel female, suggesting a conditioned avoidance of the scented female. Interestingly, the familiar females in both groups displayed significantly more female-female mounting of the novel female during the open field test, suggestive of a conditioned effect on mate guarding and dominance in the females.
Conclusion: These findings indicate that the activation of endogenous opioid systems in males during and after ejaculation creates a reward state in which salient cues of a female partner become preferred.
Supported by CIHR (JGP).
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