Penile erection in response to remote cues from females: albino rats severely impaired relative to pigmented strains

Male rats have been observed to display erections when exposed to inaccessible estrous females, and it was suggested that these "noncontact erections" (NCEs) represent a species-typical response that may index sexual arousal. Initial efforts in other laboratories to repeat and extend this research were unsuccessful, and it appeared that differences in the rat strains being used might be responsible. To address this question NCE tests were given to rats of two albino strains, Wistar and Sprague-Dawley, and two pigmented strains, hooded Long-Evans and inbred Brown Norway. A high proportion of Long-Evans and Brown Norway rats displayed NCEs, whereas Wistar and Sprague-Dawley albino rats rarely did. Additional experiments did not reveal the reasons for the strain difference in NCE, but they provided evidence against hypotheses based on the relative erectogenic effect of albino and hooded estrous females, the attention paid to estrous females, the motor repertoire, or erectile function per se. Albinism-related neural pathology, possibly outside of the visual system, may contribute to the deficit in NCE in albino rats.