Endocrine and body growth traits in heifers exposed to testosterone-propionate during early fetal development.
This study was conducted to determine the effects of testosterone-propionate exposure during fetal development on sexual differentiation and growth rates in heifers. Ten pregnant cows were given subcutaneous injections of testosterone-propionate (250 mg/injection) every other day during d 40 to 60 of gestation. Four cows aborted after the end of testosterone treatment, while four heifers (androgenized females) and two bulls (androgenized males) were produced from the six remaining pregnant, testosterone-propionate treated cows. Calves from cows that did not receive exogenous hormone treatment were used as controls. At 8 mo of age, the androgenized heifers and control heifers and control steers were challenged with 1 mg estradiol-17 beta to induce a preovulatory luteinizing hormone (LH) surge. Two weeks later, pituitary responsiveness to exogenous luteinizing hormone releasing hormone (LHRH; 75 micrograms) was evaluated in androgenized heifers and in control heifers and control steers. To monitor growth rates, all animals were weighed at 28-d intervals from birth to 380 d of age. Androgenized females exhibited a partially masculinized phenotype as well as internal male reproductive structures. Treatment with estradiol-17 beta first depressed (P less than .05) serum LH concentrations in all animals, then induced (P less than .05) a preovulatory-like LH surge in control and androgenized females. Control steers did not (P greater than .05) exhibit a preovulatory-like LH surge following administration of estradiol-17 beta. Exogenous LHRH treatment stimulated peak LH concentrations (P less than .05) to a greater extent in control and androgenized females than in control steers.(ABSTRACT TRUNCATED AT 250 WORDS)
Hamernik
D L
DL
McFarland
S Y
SY
de Avila
D
D
Becker
S R
SR
Reeves
J J
JJ
D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002417:Cattle / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005333:Fetus / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D011247:Pregnancy; D013739:Testosterone / Q000494:pharmacology*
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone