Homosexual and heterosexual partner preference in ovariectomized female rats: effects of testosterone, estradiol and mating experience.
Ovariectomized female rats, longterm treated with estradiol benzoate (EB, 20 micrograms, 3 x/week) or testosterone propionate (TP, 0.4 mg, 3 X/week), were tested for homo- or heterosexual partner preference behavior with either tethered animals (sexually active male vs. estrous female) or animals behind a wire mesh. A preference score was calculated by subtracting the time spent in the vicinity of the stimulus female from the time spent in the vicinity of the stimulus male. Thus, a positive score indicates preference for the male (heterosexual preference), a negative score preference for the female (homosexual preference). Two weeks of EB treatment caused a clearcut preference for the male incentive. This heterosexual preference was significantly different from the indistinct preference of the TP-treated females. Sexual interaction with a freely moving active male (with or without a vaginal mask which prevented intromissions) did not alter the preference for the male of the EB-treated females. It did affect, however, the preference behavior of the TP-treated females significantly: it changed in the direction of the sexually active estrous incentive female, i.e., a homosexual preference. This change in preference could not be attributed to the experience of penile intromissions, it occurred despite the presence of a vaginal mask. Apparently, being mounted by a sexually active male had a negative reinforcing value in the TP-treated female rats and provoked a homosexual partner preference.
Department of Endocrinology, Growth and Reproduction, Faculty of Medicine, Erasmus University, Rotterdam, The Netherlands.
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Slob
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de Klerk
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Brand
D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D008297:Male; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D013739:Testosterone / Q000494:pharmacology
D013739:Testosterone; D004958:Estradiol