Sexual behaviour of male rats injected with the anti-oestrogen MER-25 during infancy
Booth, J.E.
Physiology and Behavior 19(1): 35-39
1977
ISSN/ISBN: 0031-9384 PMID: 11803687 Document Number: 434814
Newborn male rats were injected s.c. with 50, 100 or 200 .mu.g MER-25 or 0.05 ml oil daily for the first 10 days of life. As adults, they were tested for male sexual behavior both before and after castration and replacement with testosterone propionate, and for female sexual behavior after injections of estradiol benzoate followed by progesterone. Injections of 100 and 200 .mu.g MER-25/day during infancy caused significantly fewer rats to ejaculate than 0.05 ml oil/day in both series of tests for male sexual behavior. The reduced occurrence of ejaculation could not be related to defective penile development as there was no significant difference in penis weights or the numbers of penile spines between the MER-25 and oil-injected rats. All doses of MER-25 caused significantly more lordosis behavior after estrogen and progesterone than did injections of oil. These results provide further evidence that neonatal testicular androgens must be converted to estrogen in the brain in order to organize male sexual behavior patterns, including the neural substrate for ejaculation, as well as to suppress female sexual behavior.