Serum Progesterone and Estradiol-17β Concentrations in Captive and Free-Ranging Adult Female Japanese Black Bears (Ursus thibetanus japonicus)

摘要: Progesterone (P4) and estradiol-17β (E2) concentrations were measured in serum samples obtained from 23 captive free-ranging adult female Japanese black bears. We then determined the relationship between changes these sex steroid hormones pregnancy. In all bears, which included animals of both known unknown reproductive status, P4 low April to July, tended become higher after August. The levels became much still November December, but returned March. Serum eight pregnant had parturitions following spring, increased gradually August (0.5-2.4 ng/ml) October (0.9-3.6 ng/ml), achieved significantly maximum December (7.2-18.0 ng/ml). Thereafter, decrease (3.5-6.4 ng/ml January 0.3-0.7 March). E2 varied showed high January. bears May (95.6-191.4 pg/ml) (35.6-143.3 pg/ml). Subsequently, dropped lower minimum (5.3-11.9 again (67.6-153.1 Among data on led expectations pregnancy, whereas no distinct evidence related These results, particularly indicate that a marked increase might be accompanied by reactivation corpus luteum preceding implantation. Furthermore, suggested possibility decline an are associated with implantation parturition, respectively.