Decrease In Plasma Progesterone Levels Research Articles

Reversible infertility in a liver receptor homologue-1 (LRH-1)-knockdown mouse model

Liver receptor homologue-1 (LRH-1) is an orphan nuclear receptor that has been implicated in steroid hormone biosynthesis and fertility. Herein we describe a transgenic inducible short hairpin (sh) RNA mouse model that was used to study the effect of transient LRH-1 knockdown in vivo. Induction of expression of the shRNA directed against LRH-1 for 2-6 weeks resulted in 80% knockdown of LRH-1 protein in the ovary and complete infertility. Gonadotropin hyperstimulation could not rescue the observed defects in ovulation and corpus luteum formation in LRH-1-knockdown mice. The infertility phenotype was fully reversible because LRH-1-knockdown females became pregnant and delivered normal size litters and healthy pups after cessation of LRH-1 shRNA expression. Timed ovarian microarray analysis showed that, in line with the observed decrease in plasma progesterone levels, key steroid biosynthesis genes, namely Star, Cyp11a1, Hsd3b and Scarb1, were downregulated in LRH-1-knockdown ovaries. In contrast with what has been described previously, no clear effect was observed on oestrogenic activity in LRH-1-knockdown mice. Only Sult1e1 and, surprisingly, Hsd17b7 expression was modulated with potentially opposite effects on oestradiol bioavailability. In conclusion, the fully reversible infertility phenotype of LRH-1-knockdown mice shows the feasibility of an LRH-1 antagonist as new contraceptive therapy with a mechanism of action that most prominently affects cholesterol availability and progesterone production.

Imbalance in Sex Hormone Levels Exacerbates Diabetic Renal Disease

Studies suggest that the presence of testosterone exacerbates, whereas the absence of testosterone attenuates, the development of nondiabetic renal disease. However, the effects of the absence of testosterone in diabetic renal disease have not been studied. The study was performed in male Sprague-Dawley nondiabetic, streptozotocin-induced diabetic, and streptozotocin-induced castrated rats (n=10 to 11 per group) for 14 weeks. Diabetes was associated with the following increases: 3.2-fold in urine albumin excretion, 6.3-fold in glomerulosclerosis, 6.0-fold in tubulointerstitial fibrosis, 1.6-fold in collagen type I, 1.2-fold in collagen type IV, 1.3-fold in transforming growth factor-beta protein expression, and 32.7-fold in CD68-positive cell abundance. Diabetes was also associated with a 1.3-fold decrease in matrix metalloproteinase protein expression and activity. Castration further exacerbated all of these parameters. Diabetes was also associated with a 4.7-fold decrease in plasma testosterone, 2.9-fold increase in estradiol, and 2.1-fold decrease in plasma progesterone levels. Castration further decreased plasma testosterone levels but had no additional effects on plasma estradiol and progesterone. These data suggest that diabetes is associated with abnormal sex hormone levels that correlate with the progression of diabetic renal disease. Most importantly, our results suggest an important role for sex hormones in the pathophysiology of diabetic renal complications.

Ovarian vitamin E accumulation: evidence for a role of lipoproteins.

Reactive oxygen species, such as superoxide, hydrogen peroxide, and lipid peroxides, impair luteal function. Vitamin E, a lipophilic antioxidant vitamin, provides a major avenue of protection by scavenging free radicals and terminating lipid peroxidation. We previously showed that ovarian vitamin E levels increase after functional regression (loss of progesterone production) of the corpus luteum in the pseudopregnant rat and the objective of the present studies was to determine the mechanism(s) that resulted in such increased levels of vitamin E. Luteal vitamin E levels were significantly elevated after function regression and remained elevated. Luteal cholesterol ester levels, in contrast, decreased in parallel with the decrease in plasma progesterone levels, whereas plasma vitamin E, cholesterol, and cholesterol ester levels did not change. Because vitamin E is transported in blood by chylomicrons and lipoproteins, ovarian vitamin E levels were determined after treatments known to modify ovarian lipoprotein receptor content and serum lipoproteins. Acute treatment with aminoglutethimide during the mid-luteal phase decreased serum progesterone levels and increased luteal vitamin E and cholesterol ester levels. Daily treatment with 4-amino-pyrazolo-(3,4-d)pyrimidine reduced serum vitamin E and cholesterol ester levels, diminished the accumulation of vitamin E associated with luteal regression, significantly reduced luteal cholesterol esters levels, and increased luteal high density lipoprotein-binding sites. Analysis of the distribution of vitamin E between a membrane/particulate pellet and a lipid droplet/granule cytosol before and after luteal regression revealed no changes. Vitamin E levels were divided 60:40 between a crude particulate/membrane fraction and a cytosol/lipid droplet fraction, although functional regression produced a 2.5-fold increase in total luteal vitamin E levels. In conclusion, the uptake of vitamin E by the corpus luteum appears to be mediated by lipoprotein receptors and the increase in vitamin E that follows functional regression, we suggest, may be due to a diminished consumption of vitamin E by oxidative radicals, most likely generated during steroidogenesis.

Changes in Levels of Messenger Ribonucleic Acid for Cytochrome P450 Side-Chain Cleavage and 3β-Hydroxysteroid Dehydrogenase during Prostaglandin F2α-Induced Luteolysis in Cattle1

Regression of the CL causes a dramatic decrease in plasma progesterone levels. To test the hypothesis that the decrease in progesterone involves the down-regulation of mRNA encoding the steroidogenic enzymes, cytochrome P450 side-chain cleavage (P450scc) and/or 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), levels of plasma progesterone and luteal mRNA for P450scc and 3 beta-HSD were measured and correlated during induced luteolysis. Holstein heifers (n = 25) were injected with 25 mg prostaglandin F2 alpha (PGF2 alpha) on Day 6 or 7 of the estrous cycle (Day 0 = estrus) to induce luteal regression. To determine acute changes in plasma progesterone during luteolysis, jugular blood samples were obtained from 5 heifers hourly for 12 h, beginning immediately before injection of PGF2 alpha, and assayed for progesterone by RIA. A significant decrease in plasma progesterone levels was observed as early as 1 h after the PGF2 alpha injection (3.62 vs. 2.72 ng/ml, p < 0.05). Progesterone levels continued to decline with time through 12 h after administration of PGF2 alpha. The other 20 animals were ovariectomized at 0 (n = 6), 2 (n = 4), 12 (n = 4), or 24 (n = 6) h after PGF2 alpha. Levels of P450scc and 3 beta-HSD mRNA were determined in extracts of total luteal RNA by ribonuclease (RNase) protection assay. By 2 h after PGF2 alpha, 3 beta-HSD mRNA levels had decreased by about 40% as compared with levels at time 0 (p < 0.05), and a further significant decrease occurred between 2 and 12 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrinological and behavioral changes associated with the onset of incubation in the duck

Plasma levels of prolactin were measured during the onset of incubation in ducks. A rapid rise in prolactin levels from a mean of 5.7 to 33.1 ng/ml occurred during the formation of the final 20% of the clutch; during which the females increased their nest-box occupancy from 9.9 to 22.2 hours per day. A pronounced decrease in plasma progesterone levels, but not estradiol, occurred in females in the days immediately preceding the onset of incubation and termination of egg laying. A similar decrease in plasma LH occurred. Plasma corticosterone levels also decreased during the transition from egg laying to incubation. In male ducks, who play no role in incubation, LH remained constant until well into incubation when it decreased. Changes in plasma levels of prolactin are discussed in relation to tactile stimulation from the clutch and nutritional stress.

Relationships between plasma progesterone levels and testicular testosterone production in the rat fetus: effects of maternal ovariectomy.

The present study was performed to examine whether circulating progesterone regulates testicular testosterone production in the fetal rat. Progesterone levels in fetal plasma were found to increase from day 14.5 to day 16.5; thereafter they reached a plateau between days 16.5 and 18.5 (80 nmol/l) and decreased threefold between days 18.5 and 21.5. The addition of progesterone, within the range of normal plasma concentrations, induced a dose-dependent increase in testosterone produced in vitro by the testes on days 16.5 and 18.5 but not on day 20.5. However, in 18.5-day-old fetuses, individual plasma progesterone levels were not correlated with testicular testosterone production in vivo and in vitro. Furthermore, maternal bilateral ovariectomy induced a significant fall in plasma progesterone in 18.5-day-old fetuses; this was not associated with a reduction in plasma testosterone nor in testicular testosterone content, although the amount of testosterone secreted by the testis incubated in vitro was slightly but significantly reduced. It is concluded that circulating progesterone does not regulate testicular testosterone production in vivo although the testis may use plasma progesterone as a substrate. On day 18.5 after maternal ovariectomy, the decrease in plasma progesterone levels was similar in fetuses and mothers, suggesting that most fetal progesterone originates from maternal plasma.

Intrauterine Extra-Amniotic 15(S)-15-Methyl Prostaglandin F2α for Induction of Early Midtrimester Abortion

Twenty-six patients 13 to 15 weeks pregnant received extraovular 15(S)-15-methyl prostaglandin F2 alpha in a dosage of 1 mg every 18 to 24 hours for three doses. Twenty-five (96%) of the patients aborted; fifteen patients aborted incompletely. The mean induction-to-abortion time was 15.8 hours. A decrease in plasma progesterone levels could not be consistently correlated with abortifacient activity, and there was no statistically significant relationship between abortion time and parity or gestational age. One patient failed to abort after 36 hours of therapy and was aborted by curettage. She was the only patient who developed a postabortion uterine infection. Results with the extraovular technique appear to be similar to those with the intra-amniotic and the intramuscular prostaglandin techniques. Therefore, extraovular administration may be useful for inducing abortion in patients who are in the early midtrimester of pregnancy.