The metabolic clearance rate of progesterone in the pregnant rhesus monkey

Active immunization of rabbits against progesterone: increase in hormone levels, and changes in metabolic clearance rates and in genital tract tissues

11 alpha-Hemisuccinyl progesterone was coupled to rabbit serum albumin and injected into intact male rabbits, and into intact ovariectomized female rabbits, for a period of 52 weeks. The ovariectomized females and the intact males showed better immune responses than the intact females. Specificity of the antisera was tested against both progesterone and the carrier protein, and against 19 other selected steroids. Antibody titres and serum levels of progesterone in all groups, and testosterones in the males, showed characteristic changes with a first maximum 12-18 weeks after the beginning of immunization, a decrease despite booster injections and a second increase after 35-40 weeks. Hormone levels were 5-12 times higher by the end of immunization than before. High antibody titres were correlated with decreased metabolic clearance rates for progesterone, reflecting the binding of the steroid to the antibody. Increased production rates of progesterone in the immunized females and of testosterone in the immunized males showed that the antibody-bound hormone was not available for feedback control. Absence of primordial follicles, hyperplasia of the Leydig cells, decreased spermatogenesis and involution of the seminal vesicle epithelium were interpreted as direct or indirect effects of the removal of free progesterone.

Breech delivery: evaluation of the method of delivery on perinatal results and maternal morbidity

A retrospective study of 460 single-gestation infants in breech position was conducted at the University of Colorado Medical Center to assess the impact of a policy for the selection of cases for vaginal delivery. Among infants weighing more than 2,500 grams, there was an increase in the cesarean section rate from 13% to 54%, with an associated increase in maternal morbidity from 7% to 15%. This occurred with no significant reduction in adverse perinatal outcome. However, a case-by-case review suggests that more frequent and timely cesarean sections would have further reduced perinatal morbidity and deaths among term infants. Among the infants weighing 2,500 grams or less there was an increase in cesarean births from 5% to 55% following the introduction of the strict criteria for vaginal delivery. Among the infants weighing 1,501 to 2,500 grams there was no significant difference in survival between the cesarean and vaginally delivered patients. Although infants weighing 501 to 1,500 grams delivered by cesarean section survived more frequently than did those delivered vaginally, the differences in perinatal deaths may have been due to a higher birth weight in the cesarean-delivered infants or an over-all improvement in neonatal intensive care for infants of very low birth weight.

In vitro metabolism of progestins. III. The metabolic clearance rate of medroxyprogesterone acetate in monkeys

3H-medroxyprogesterone acetate (MPA) was synthesized by selective catalytic tritiation of the delta1-olefinic bond of 6alpha-methyl-17alpha-hydroxy-pregna-1,4-diene-3,20-dione acetate. The metabolic clearance rate of MPA (MCRMPA) was determined in 9 female Rhesus monkeys by the single injection technique. The blood MCRMPA was 201 +/- 19 L/day (42.2 +/- 4.0 L/day/kg) which was approximately the same as that reported for progesterone clearance in the monkey. We conclude that a greater biological activity of MPA compared to progesterone cannot be related to its prolonged retention in the blood. Although both MPA and amino-glutethimide alter the rate of steroid metabolism in some species, neither of these agents influences the metabolic clearance rate of 3H-MPA in the monkey.

Placental and luteal steroidogenesis in the pregnant rhesus monkey

Progesterone, 20alpha-dihydroprogesterone, estrone and estradiol-17beta concentrations were estimated by radioimmunoassay in blood plasma from uterine, uteroovarian and femoral veins of rhesus monkeys (Macaca mulatta) on days 22, 49, 128 and 160 of gestation. Steroids were consistently more concentrated in uterine and uteroovarian that in femoral venous plasma and in many cases levels in the uteroovarian vein were also higher than those in the uterine vein indicating luteal secretion of both progestins and estrogens thoughout gestation. In some animals, however, the corpus luteum appeared quiescent. As reflected in the decline in the uterine venous progesterone/estradiol-17beta concentration ratio, a shift in steroid contribution from the uterus and its contents occurred between days 22 and 49 of gestation with progesterone declining more rapidly than estradiol-17beta. Progesterone/20alpha-dihydroprogesterone was higher in both uterine and uteroovarian than in femoral venous plasma suggesting peripheral metabolism of progesterone to 20alpha-dihydroprogesterone.

In vivo aspects of progesterone distribution and metabolism

The end-organ response of any hormone is the result of many factors which precede the event, including biosynthesis, secretion, transport, distribution, and metabolism. These factors vary among different species. The metabolic clearance rate (MCR) of progesterone varies between 40 and 180 L./day/Kg. in man (60 to 70), monkey (40 to 50), rabbit (55 to 60), sheep (110), rat (120), and guinea pig (180). Major sites of clearance include liver, brain, and uterus. Specific metabolites of progesterone include 20 alpha-hydroxypregn-4-en-3-one (20 alphaOHP) and alpha-pregnan-3,20-dione (5 alpha-DPH). Liver, brain, and uterine clearances, extractions, and conversions of progesterone to these metabolites have been studied in various species under apparent steady-state conditions. A specific hormone action of progesterone, the appearance of uteroglobin in the rabbit uterus, has also been studied in varying horomonal states (estrogen, estrogen plus progesterone, and progesterone alone). These have all been used as examples of progesterone distribution and metabolism.