Stimulus animal characteristics do not modulate the expression of partner preference by female rats

The stimulus animals used in tests of partner preference in female rats vary. To test the hypothesis that the alternative stimulus animal modulates the preference for an intact male, gonadectomized (GDX) female rats received estradiol benzoate plus progesterone or the oil vehicle and were tested for partner preference with either an intact male paired with a GDX hormone-primed female or an intact male paired with a GDX male. Rats were tested under conditions that limited physical contact (No Contact) or allowed sexual interaction (Contact). Stimulus animal condition was not a primary determinant of partner preference. In contrast, contact condition and hormone treatment modulated preference, as well as activity levels and the display of proceptive behaviors. Our findings demonstrate that the characteristics of the alternative stimulus animals tested here do not play a significant role in modulating partner preference in female rats.