Sexual experience, androgens and female choice of a mate in laboratory rats

Sexual experience produces long-lasting changes in both the behaviour and reproductive system of a male rat. The response of the female rat to an area that had recently housed a previously mated male was investigated in three experiments. In experiments 1 and 2 females preferentially urine marked in an area vacated by a sexually experienced (SE) male relative to areas vacated by a sexually inexperienced (SI) or castrated (C) male. The density of female marks were ranked SE greater than SI greater than C greater than empty area. In experiment 3 female preference of an SE male with varied and multiple mating experiences was magnified when compared with an SI male. There was the suggestion that the multiple SE male was even preferred to a male with only a single mating experience. A fourth experiment demonstrated an acute increase in circulating testosterone in multiple SE males exposed to oestrous or non-oestrous females, and the increase was observable for up to 7 days after exposure to an oestrous female. The conclusion is that chronic changes in androgen-dependent urinary by-products released by the SE male mediate the discrimination and choice of a mate by the female rat.