Blood Progesterone Levels in Relation to Parturition

Short, R. V.

doi:10.1530/jrf.0.0010061

Cited by 47 publications

(6 citation statements)

References 29 publications

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“…The absence of progesterone in a detectable quantity on the day of calving in contrast to its presence in relatively higher concentra¬ tion 10 to 15 days before (26 Mg/g) supports this conclusion further. Short (1960) found a decrease in the blood level of progesterone before calving.…”

Section: Discussionmentioning

confidence: 95%

Some Pituitary-Ovarian Relationships in the Periparturient Cow

Labhsetwar¹,

Collins²,

Tyler³

et al. 1964

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Summary. An The corpora lutea were significantly larger in the ante-partum group than in the day-of-calving group. A significantly higher fsh level and lower lh level was found in the pituitaries of the day-of-calving group. Follicular size was significantly lower in the ante-partum and day-of-calving group as compared to both the post-partum groups. Injection of progesterone produced no significant alterations in fsh and lh levels of the pituitary glands. Neither did it depress ovarian follicular growth.

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Section: Discussionmentioning

confidence: 95%

Some Pituitary-Ovarian Relationships in the Periparturient Cow

Labhsetwar¹,

Collins²,

Tyler³

et al. 1964

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“…Though progesterone could be detected in equine placenta, it could not be detected in equine blood in mid-to-late gestation (Short 1959). Appearing to be unique among species studied in this regard, the possible existence in horses of an alternative progestin other than progesterone was proposed (Short 1960).…”

Section: Progesterone and 5α-dihydroprogesterone (Dhp) Bioactive Promentioning

confidence: 99%

Steroids in the establishment and maintenance of pregnancy and at parturition in the mare

Conley

Ball

2019

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Historically, studies on the endocrinology of pregnancy and parturition in horses have made major contributions of relevance to mammals in general. Recent use of liquid chromatography mass spectrometry, measuring multiple steroid hormones simultaneously in blood, foetal and placental tissues throughout normal gestation, and in mares with experimentally induced placentitis, has advanced our current understanding of many of the unusual strategies seen during gestation and at foaling. This includes the stimulation of luteal steroidogeneisis by equine chorionic gonadotropin (eCG) from the endometrial cups, resulting in additional androgen and oestrogen secretion. Progesterone declines as the endometrial cups and eCG disappears, replaced by 5α-dihydroprogesterone (DHP), a potent equine progesterone receptor (PR) agonist, as the chorioallantoic placenta develops. Placental steroidogenesis thereafter is influenced by foetal pregnenolone and dehydroepiandrosterone secretion, providing substrate for 5α-pregnane and oestrogen synthesis, an unusual example of a ‘foeto-placental unit’. Foetal gonadal dehydroepiandrosterone fuels placental oestrone sulphate secretion, peaking at higher concentrations in mares than any other species known, declining steadily thereafter to term. Additional 5α-reduced (DHP) metabolites increase from mid-gestation to peak concentrations 3–5 days before foaling, declining prepartum, most likely as a result of selective loss of placental SRD5A1 (5α-reductase) expression and activity. Similar changes occur in mares with experimentally induced placentitis, which is also associated with a decreased ratio of equine PR-B:PR-A in myometrium, suggesting that progestin withdrawal is both systemic (pregnanes) and local (receptor-dependent) in mares. In addition, some steroids detected during equine pregnancy by immuno-assay are not detected by mass spectrometry, further illustrating the immense value of this technology.

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“…Information on peripheral plasma values of progesterone in the sow during the puerperal period is lacking. Short (1960) published the values that he obtained for sows at different stages of pregnancy up to day 114 of gestation. The concentrations were 10.4 ng/ml and 12.0 ng/ml on day 99 and day 102 of pregnancy respectively.…”

Section: Corticoidsmentioning

confidence: 99%