title: Induction of pseudopregnancy in the American Black Bear (Ursus americanus).
abstract: The aim of this study was to determine whether American Black Bears (Ursus americanus) can experience a pseudopregnancy of the same duration as pregnancy. To do this, we treated three nonmated, captive female bears with human chorionic gonadotropin (hCG) during one breeding season, and saline during another. Progesterone concentrations were measured in monthly blood samples to determine whether pseudopregnancy had occurred. Elevated progesterone concentrations were observed in two out of three bears treated with hCG. We conclude that 1) Elevated progesterone concentrations can be induced in black bears by injection of 35 U/kg hCG during the mating season. 2) Bears can experience a pseudopregnancy, identical in length to pregnancy, in which progesterone profiles are indistinguishable from those of pregnancy.
authors.affiliation: Department of Molecular and Integrative Physiology, University of Illinois, Urbana-Champaign, IL 61801, USA.
authors.forename: Laura Clamon
authors.initials: LC
authors.lastname: Schulz
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Nelson
authors.forename: Leah M
authors.initials: LM
authors.lastname: Pyter
authors.forename: Janice M
authors.initials: JM
authors.lastname: Bahr
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin; D030762:Estrous Cycle / Q000097:blood*; D005260:Female; D011374:Progesterone / Q000097:blood*; D011555:Pseudopregnancy / Q000097:blood* / Q000139:chemically induced; D001503:Ursidae / Q000097:blood*
chemical_list: D006063:Chorionic Gonadotropin; D011374:Progesterone