title: Seasonal variations in circulating levels of progesterone and estradiol in unmated adult female woodchucks (Marmota monax) in captivity.
abstract: The annual profile of serum levels of progesterone (P) and estradiol-17 beta (E2) was characterized in a seasonally breeding rodent, the woodchuck (Marmota monax). Hormonal levels were determined in serum samples taken at weekly or biweekly intervals from unmated female woodchucks maintained all year indoors under controlled conditions of photoperiod and temperature. Annual fluctuations included a rise of E2 levels during late January through February, followed by a modest increase in plasma P concentrations by late March, the latter attaining peak values during April and May. A temporal dissociation of peak values of circulating levels of P and E2 during the annual reproductive cycle was also detected. The timing of changes in serum levels of P and E2 in these captive woodchucks corresponded to reproductive events during the normal breeding season of the woodchuck in the southern part of its range.
authors.affiliation: Department of Physiology, School of Medicine, Southern Illinois University, Carbondale 62901-6512.
authors.forename: A P
authors.initials: AP
authors.lastname: Hikim
authors.forename: A G
authors.initials: AG
authors.lastname: Amador
authors.forename: A
authors.initials: A
authors.lastname: Woolf
authors.forename: A
authors.initials: A
authors.lastname: Bartke
authors.forename: C
authors.initials: C
authors.lastname: Gremillion-Smith
mesh_terms: D000818:Animals; D004958:Estradiol / Q000097:blood*; D004971:Estrus; D005260:Female; D008392:Marmota / Q000378:metabolism / Q000502:physiology*; D011374:Progesterone / Q000097:blood*; D012621:Seasons; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol