Cryptorchidism and the pituitary--testicular axis in bulls
Schanbacher, B.D.
Journal of Reproduction and Fertility. Supplement 30: 67-73
1981
ISSN/ISBN: 0449-3087 PMID: 6132006 Document Number: 171868
In 10 Hereford X Aberdeen-Angus calves made cryptorchid at birth, serum LH concentrations were elevated (P<0.01) over those of 10 sham-operated controls by 7 wk of age, a difference which persisted until after puberty. When intact and cryptorchid bulls were given intravenous LHRH, at approx. 18 months of age, cryptorchid bulls were more responsive. Serum LH concentrations after treatment with 250, 1000 and 4000 ng LHRH were 0.2 plus or minus 0.03, 1.2 plus or minus 0.3 and 12.1 plus or minus 2.0 ng/ml resp. for intact bulls, and 1.0 plus or minus 0.6, 5.1 plus or minus 0.8 and 19.6 plus or minus 2.1 ng/ml for cryptorchid bulls. Testes from cryptorchid bulls weighed less (P<0.01) than testes from intact bulls (68 plus or minus 6 vs. 655 plus or minus 36 g) at 24 months of age. The ability to secrete testosterone in vitro was determined by incubating minced pieces of testes at 36 deg C for 3 h in Krebs-Ringer-bicarbonate buffer (pH 7.2) containing 1 mg glucose/ml and 100 mIU HCG/ml. Cryptorchid testes secreted slightly more testosterone than scrotal testes on a unit weight basis, but when expressed on a paired testis weight basis, testosterone secretion by cryptorchid testes was less (8 plus or minus 2 vs. 60 plus or minus 10 mg, P<0.01). Autoradiographic localisation techniques were used to show the existence of LH/HCG binding sites in cryptorchid testes. These studies suggest that cryptorchid bull testes have a reduced capacity to secrete testosterone, and that near-normal serum testosterone concentrations are maintained in the presence of increased serum gonadotropins.