Suppression of lordosis in the hormone-primed female hamster by electrical stimulation of the septal area

The behavior of the female hamster toward the male is altered radically by estrogen and progesterone. Her aggression gives way to sexual receptivity, and the lordosis posture will commonly be maintained in the presence of a sexually active male for greater than 10 min at a time. The septal area is one of the limbic and hypothalamic areas which preferentially accumulate radioactive estradiol in the female hamster. In order to determine whether this region is involved in lordosis control, we examined the effects of electrical stimulation (ES) there on the copulatory behavior of ovariectomized, hormone-primed, sexually receptive females in the presence of sexually active males. Sixty second trains of 100 Hz, 0.2 msec, biphasic, square-wave pulses at either 80 or 90 μA were effective in suppressing the lordosis response in 8 of 13 animals with electrodes in the septal area. In the most effective cases ES would prevent lordosis even during persistent contacts and mount attempts by the male. Some neurons in the septal area may be part of a network acting to inhibit the display of lordosis. One of the ways ovarian hormones could facilitate lordosis is through reduction of the suppressive activity in such a network.