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EFFECTS OF PERINATAL PROGESTERONE MANIPULATIONS AND MATERNAL AGE ON FEMALE SEXUAL BEHAVIOR IN THE RAT
Abstract
Three experiments were performed to investigate the role of progesterone in sexual differentiation. Results indicated that perinatal progesterone injections feminized neonatally castrated males and males castrated at 30 days of age. Specifically, progesterone treatment increased the male rat's behavioral sensitivity to estrogen and to progesterone. Neonatally castrated males so treated displayed lordosis behavior comparable to that of normal females. In addition, perinatal progesterone treatment of prepuberally castrated males offset the presence of testes, resulting in animals behaviorally equivalent to neonatal castrates. A complex dose-response relationship may exist between neonatal progesterone treatment and lordosis behavior. Higher lordosis scores were seen in males administered 500 (mu)g progesterone neonatally than in males treated with either lower or higher dosages. In females ovariectomized as adults, high levels of neonatal progesterone resulted in defeminization. Maternal age was shown to influence the sexual behavior of female offspring. Since progesterone levels during pregnancy decrease with age, offspring of old mothers are exposed to lower prenatal levels of progesterone than offspring of young mothers. Females born to 10-month or 13-month old mothers displayed less lordosis than those born to younger mothers. In addition, the litters of old mothers contained a significantly greater percentage of males than the litters of young mothers. However, maternal age rather than percentage of male littermates was the best predictor of lordosis behavior. It was concluded that the data support a modified version of a circular model of sexual differentiation. The testosterone to progesterone (T:P) ratio existing in an organism during development may be an important factor, and optimal T:P ratios may exist for male and female development.
Subject Area
Physiological psychology
Recommended Citation
NIKELS, KENNETH WILLIAM, "EFFECTS OF PERINATAL PROGESTERONE MANIPULATIONS AND MATERNAL AGE ON FEMALE SEXUAL BEHAVIOR IN THE RAT" (1982). ETD collection for University of Nebraska-Lincoln. AAI8306494.
https://digitalcommons.unl.edu/dissertations/AAI8306494