Plasma progesterone concentrations in pregnant and nonpregnant black bears (Ursus americanus)

Abstract

Plasma levels of progesterone were determined from serial samples taken from 2 black bears over 3 consecutive fall periods. Each animal was pregnant during the 1st and 3rd years. Variations in progesterone levels were seen between animals and within each animal between pregnancies. Average baseline levels during the mid-to-late preimplantation period were 5.0-12.5 ng/ml and increased 2-3 fold at the approximate time of implantation. Values during non-pregnancy were detectable but much lower (0.6-2.5 ng/ml). The observed pattern of progesterone secretion in this species appears consistent with that reported for other species exhibiting obligate delayed implantation.

Unique biphasic progestagen profile in parturient and non-parturient giant pandas (Ailuropoda melanoleuca) as determined by faecal hormone monitoring

“…However, ours was the first effort to differentially quantify the duration, amplitude and temporal excretion patterns between the two phases and across a large cohort of pregnant versus non-pregnant individuals of this rare species. The post-ovulatory biphasic progestagen profiles for the giant panda generally were highly consistent with findings in other ursids (American black bear; Foresman & Daniel 1983, Palmer et al 1988, Hellgren et al 1991, Tsubota et al 1998, Schulz et al 2003 Mead 1981). This includes earlier suggestions that the duration of the secondary phase is less variable than that of the primary phase (Enders 1952, Murphy & Moger 1977, Allais & Martinet 1978, Papke et al 1980, Canivenc & Bonnin 1981, Mead 1981, Foresman & Daniel 1983.…”

“…The post-ovulatory biphasic progestagen profiles for the giant panda generally were highly consistent with findings in other ursids (American black bear; Foresman & Daniel 1983, Palmer et al 1988, Hellgren et al 1991, Tsubota et al 1998, Schulz et al 2003 Mead 1981). This includes earlier suggestions that the duration of the secondary phase is less variable than that of the primary phase (Enders 1952, Murphy & Moger 1977, Allais & Martinet 1978, Papke et al 1980, Canivenc & Bonnin 1981, Mead 1981, Foresman & Daniel 1983. Enders (1952) first postulated that the second, enhanced P 4 rise was associated with implantation of a previously free-floating embryo, a concept later proven for the mink (Allais & Martinet 1978, Murphy et al 1993, Douglas et al 1998, European badger (Canivenc & Bonnin 1981, Yamaguchi et al 2006) and spotted skunk (Mead 1981).…”

Reproductive Pattern of the Sun Bear(Helarctos malayanus) in Sarawak, Malaysia.

“…In the present study, the three females showed increasing fecal P 4 concentrations and lactation without mating stimulus. An increased serum P 4 level has been reported in pregnant polar bears (Ursus maritimus), pregnant American black bears (Ursus americanus), pregnant Hokkaido brown bears (Ursus arctos yesoensis) and non-pregnant Hokkaido brown bears that were segregated from males during breeding season [7,15,25,26]. Non-pregnant and pregnant Hokkaido brown bears exhibited the similar annual change of serum P 4 levels, and a similar phenomenon was reported in unmated female American black bears [24,25].…”

Changes in progesterone concentrations in the Japanese long-fingered bat, Miniopterus schreibersii fuliginosus

“…armadillo (Labhsetwar & Enders, 1968;Peppier & Stone, 1976), stoat (Gulamhusein & Thawley, 1974), European badger (Bonnin et al, 1978), spotted skunk (Mead, 1981), northern fur seal (Daniel, 1981) and black bear (Foresman & Daniel, 1983), the corpora lutea are less active during embryonic diapause, and the plasma progesterone concentrations stay slightly above the values in non-pregnant animals until shortly before implantation, when the concentrations begin to increase with activation of the corpora lutea. However, the roe deer, Capreolus capreolus, is unique in having an active corpus luteum throughout the diapause period, although no significant change is detected in the progesterone concentration until after implantation (Hoffman et al, 1978;Aitken, 1981).…”