Somatic Basis of Sexual Behavior Patterns in Guinea Pigs

Abstract

The patterns of sexual behavior displayed by 51 female guinea pigs raised in isolation were compared with those of 69 females raised with other animals. Approximately half were spayed within 5 days of birth; the remaining at 120 days of age as young adults. In a 2d experiment contact with other animals was with-held until 240 days of age. Estrus was induced by subcutaneous injections of 100 IU alpha-estradiol benzoate followed 36 hours later with 0.2 IU progesterone. The data showed that, among females reared in isolation, duration of heat was shorter, the lordosis reflex was weaker, and there was a marked reduction in the amount of male-like mounting activity. Spaying near birth augmented the effects of isolation. Social contact in late adulthood did not restore the normal pattern. For the female as for the male the organization of the neuro-muscular mechanisms mediating sexual behavior depends upon a coac-tion between genetically determined and experiential factors. The experiential factor seemed to be more effective when the animals are young. In neither sex is the presence of the gonads necessary for the action of this factor.