Sex Steroid and Prolactin Profiles in Male American Black Bears (Ursus americanus) during Denning

Toshio TSUBOTA, David L. GARSHELIS, Ralph A. NELSON, Janice M. BAHR
1999 Journal of Veterinary Medical Science  
Serum sex steroid and prolactin profiles were examined in the male American black bear, Ursus americanus during denning. Sera collected in December and the following March from 8 denning male black bears in Minnesota, U.S.A. were assayed for testosterone, estradiol-17β and prolactin. Eight bears were confirmed to be the denning mode based on a serum urea to creatinine ratio less than 10. Serum testosterone concentrations tended to increase from December to the subsequent March whereas serum
more » ... h whereas serum estradiol-17β concentrations tended to decrease during this period. There were few changes in serum prolactin concentrations between December and March. These findings suggest that spermatogenesis and testicular steroidogenesis initiated during denning may be influenced by changes in serum sex steroid concentrations in the American black bear.-KEY WORDS: bear, denning, sex steroid.
doi:10.1292/jvms.61.81 pmid:10027172 fatcat:42rnnvktfzgklartsg67tktur4