Poster Presentation The International Congress of Neuroendocrinology 2014

I still remember her perfume: differential susceptibility of association of estrous and neutral odor cues during first sexual experiences in the male rat. (#413)

Gonzalo R. Quintana Zunino 1 , Misha Jackson 1 , Mojdeh Nasr 1 , Sarah Rassi 1 , Kerstin Wenzel 1 , Andres Guizar 1 , Jim G. Pfaus 1
  1. CSBN, Psychology, Concordia University, Montreal, Quebec, Canada

Estrous odors of female rats are salient appetitive cues for male rats that compel them to move towards females in heat during their first sexual experiences. However, after baseline rate of sexual responding has been achieved, the importance of these cues tends to diminish.  We have shown previously that male rats develop a conditioned ejaculatory preference (CEP) for females scented with a neutral odor like almond or lemon (ScF) that is paired with the male’s post-ejaculatory reward state. Moreover, a male rat’s first ejaculation experience with an unscented female (UnScF) blocks subsequent odor conditioning. This “US preexposure effect” may well have been driven by the overshadowing of the neutral odor with the unconditionally appetitive estrous odors during this first experience. This hypothesis was examined in the present study.  24 sexually naive Long-Evans male rats were assigned to two groups. One group received one copulatory experience to ejaculation with a ScF (scented with almond odor). The other group received five copulatory trials to one ejaculation each with the ScF. Subsequently, all males underwent 10 one-ejaculation trials with an UnScF. On the final test, males were placed into a large open field with two sexually receptive females, one ScF and one UnScF. Males that were preexposed only once showed a significant CEP for the UnScF whereas those preexposed five times did not develop a CEP for either female. These data indicate that unconditionally appetitive estrous odors overshadow neutral olfactory cues during a male rat’s first sexual experiences. In light of our previous findings of CEP for neutral odors, we suggest that the salience of estrous odors wanes as sexual experience develops, allowing neutral odor cues to acquire associative strength and subsequently direct sexual partner preference.