The cumulative effects of estrogen on precopulatory behavior in the female Mongolian gerbil

Differences in responsiveness of precopulatory patterns to estradiol were investigated in the female Mongolian gerbil. Administration of five daily injections of 6 micrograms estradiol benzoate (EB) to ovariectomized females demonstrated that the precopulatory patterns differ in their responsiveness to EB. Estradiol benzoate shortened the latency to the first significant increase in frequency above post-ovariectomy levels for a group of precopulatory patterns (investigation of male's anogenital area, allogrooming and ventral gland marking) in comparison with a second group (approaching, leaving, investigation of the male's head, sand rolling, the present and piloerection postures). One component of precopulatory behavior (foot stomping) was not affected by EB. We suggest that the first group of more estrogen-sensitive patterns increases rapidly during early estrus as plasma estradiol-17 beta (E2) rises, whereas the second group shows peak levels later in estrus following the rise in plasma progesterone. We conclude that separable hormonal mechanisms may govern component precopulatory patterns.