Prepubertal testosterone treatment of neonatally gonadectomized male rats: defeminization and masculinization of behavioral and endocrine function in adulthood.
Testosterone (T) administered well after the neonatal "critical" period to females at a dose approximating male levels permanently defeminizes reproductive function (see companion publication). To obtain comparable data for the male, neonatally gonadectomized (NeoGx) males received T filled or empty Silastic capsules during days 15-30 of age and were studied in adulthood. Compared to controls, the T treatment resulted in reduced lordosis and proceptive behaviors, increased mounting and intromission behaviors without differences in penile reflexes or size, and reduced plasma FSH and LH surges. Twenty of twenty-three sham-NeoGx males, but only one NeoGx male, showed ejaculatory behavior despite equivalence in penile reflexes and size after detaching a frenulum when present on the penis. These results show that T can still act on neural substrates well beyond the neonatal period to defeminize and masculinize endocrine and behavioral function in the male rat. A comparison with effects in females indicates a sex difference, the male appearing to be more sensitive to these actions of T.
Bloch
G J
GJ
Department of Psychology, Brigham Young University, Provo, UT 84602, USA.
Mills
R
R
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D004702:Endocrine Glands / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D008297:Male; D009919:Orchiectomy; D010413:Penis / Q000187:drug effects / Q000254:growth & development; D011187:Posture; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D012018:Reflex / Q000187:drug effects; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D012741:Sexual Maturation / Q000187:drug effects / Q000502:physiology*; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone; D011374:Progesterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone