REDUCTION OF SEXUAL BEHAVIOR IN MALE GUINEA PIGS BY HYPOTHALAMIC LESIONS

Abstract

The influence of hypothalamic lesions upon the sexual behavior of [male] guinea pigs was studied in 9 adult animals. The normal pattern was established preoperatively in 5 animals by observing their behavior when placed singly with estrous [female][female]. Electrolytic lesions were then placed in the anterior hypothalamus. Sexual behavior with estrous [female][female] was observed in all 9 animals placing each [male] with 3 normal [female][female] for a sufficient length of time to allow each [female] to go through 2 estrous cycles. The brains, seminal vesicles and testes were prepared for histological examination. Sexual behavior was abolished postoperatively in 4 animals; in 3 animals sexual activity was greatly reduced; and in 2 animals the behavior pattern was normal. The 7 animals which showed reduction of sexual activity produced 3 pregnancies out of a total of 40 estrous periods. The 2 animals which showed normal behavior produced 4 pregnancies out of a total of 10 estrous periods. The results of electrical ejaculation tests and epididymal smears, as well as the histological condition of the testes and the seminal vesicles indicated no impairment of endocrine activity on the part of the testes or the ant. pituitary. The lesions in the 2 cases which showed normal behavior were significantly different from those in the animals which showed reduced sexual activity. The reduced sexual activity was possibly the result of the destructive lesion in the hypothalamus.