Abstract
Sexually mature Long-Evans male rats show rigid preference for odors of receptive females over those of males or ovariectomized females. Our previous study demonstrated that orchidectomy induces feminized preference (preferring males to females), which is diminished during the course of observation over a 3 week period (Xiao et al., 2003). In the present experiment, we investigated the effects of cholesterol (C), testosterone (T) or dihydrotestosterone (DHT) on odor preference in orchidectomized males. Chronic exposure was accomplished by subcutaneous implantation of Silastic capsule containing these chemicals. The preference was also determined after the removal of the capsule. Both T and DHT, but not C, produced obvious masculine preference for receptive females. Males with T also preferred castrated males to sexually active males, whereas males with DHT had no preference for castrated males. After the removal of the capsules, both T and DHT males showed transient feminized preference for 2~3 weeks. When presented with receptive females, they were capable of displaying masculine sexual behavior. The results indicate that both T and DHT can induce masculine sexual preference. The diminished androgen after the removal of the capsule is sufficient for feminine, but insufficient for masculine, preference, presumably through androgen receptor because of effectiveness in nonaromatizable androgen, DHT. We suggest that neuroendocrine system regulating sexual preference is different from that of sexual behavior. [Jpn J Physiol 54 Suppl:S223 (2004)]
