Te. Kippin et Jg. Pfaus, The nature of the conditioned response mediating olfactory conditioned ejaculatory preference in the male rat, BEH BRA RES, 122(1), 2001, pp. 11-24
We have developed a model to study the influence of conditioning on sexual
partner preference in the rat. In this model, pairing a neutral odor (almon
d) with copulation to ejaculation produces a subsequent preference to ejacu
late with females bearing that odor. We refer to this phenomenon as a condi
tioned ejaculatory preference (CEP). The present study investigates the nat
ure of the conditioned response that mediates CEP. Given equal mount and in
tromission distributions, but an unequal ejaculation distribution, we hypot
hesized that two mechanisms could account for CEP: facilitated ejaculation
or selective ejaculation. To test these hypotheses, we examined the effect
of omitting the olfactory conditioned stimulus (CS) or applying it to a non
receptive female. Males trained with the CS paired with copulation (paired-
trained males) failed to display evidence of delayed ejaculation when copul
ating with unscented females. Conversely, paired-trained males displayed CS
-elicited copulatory behavior with CS-bearing nonreceptive females. In addi
tion, we re-analyzed the data from the copulatory preference tests of previ
ous experiments for CEP-displaying males. Again, we failed to find evidence
of facilitated ejaculation with the scented female. However, the time betw
een the last mount or intromission and ejaculation was increased if either
occurred with the scented female. Furthermore, more mounts were directed to
wards the scented female near the end, but not at other points, of an ejacu
latory series. These findings suggest that the paired-trained males attend
to the scented female near the point of ejaculation, and are consistent wit
h the hypothesis that CEP is mediated by selective ejaculation. (C) 2001 El
sevier Science B.V. All rights reserved.