The influence of the hippocampus on feminine sexual behavior: dorsal-ventral distinctions

Abstract

Bilateral radio frequency lesions were made in either the dorsal or ventral hippocampus of ovariectomized rats. Sham-lesioned and unoperated rats served as controls. In the first phase of the study, subjects were tested for feminine sexual behavior after priming with varying dosages of estrogen alone and in combination with progesterone. In the second phase, the procedure was the same except progesterone dosage was varied while estrogen dosage was held constant. Lesions of the dorsal and ventral hippocampus had differential effects on soliciting, lordotic, and aggressive behaviors during both pre- and post-progesterone tests. Subjects who sustained damage to the dorsal hippocampus displayed a lower probability and intensity of lordotic behavior than controls on both pre- and post-progesterone tests. Lesions of the ventral hippocampus tended to have a significant facilitatory effect on LQ scores and heightened the lordotic intensity scores in both pre- and post-progesterone tests. The most dramatic effects were observed in the pre-progesterone tests. Holding of the lordotic posture was facilitated also. Soliciting behavior was virtually absent in pre-progesterone tests. In post-progesterone tests, soliciting behavior was markedly depressed and irratic in dorsal hippocampal-lesioned females, while ventral hippocampal-lesioned subjects showed a smaller deficit. Controls showed high levels of stable soliciting behaviors which varied proportionately to estrogen dosage. Moreover, ventral hippocampal-lesioned females were significantly more aggressive and irritable to both the stud males and the experimenter. Dorsal hippocampal- lesioned females tended to be very passive in their interactions. Varying estrogen dosage seemed to have the greatest effect on these behaviors.