A potential mechanism in medroxyprogesterone acetate teratogenesis.

MPA (medroxyprogeste)rone acetate) has been shown to be te)ratogenic in rabbits but not in rats or mice (Andrew and Staples 1977). Since normal steroid action appears to be mediated, in large part, through interaction with specific steroid receptors, it was postulated that the species difference in teratogenicity might be due to a difference in the interaction of MPA with target cells. A primary event in steroid-cell interaction is the binding of a steroid to intracellular receptors. Studies were initiated to measure the specific nature of MPA binding to glucocorticoid and progestin receptors in appropriate rat and rabbit target tissues. The competition of MPA with 3H-dexamethasone binding in liver cytosol (glucocorticoid receptor) and with 3H-progesterone binding in uterine cytosol (progesterone receptor) was determined. In rabbit liver cytosol, MPA was as effective at competing for specific dexamethasone binding as the natural glucocorticoids and considerably more effective than the nonspecific steroids. In rat liver cytosol MPA was only 10% as effective as the natural glucocorticoids and the competition could not be distinguished from that of nonspecific steroids. A similar species difference was not seen in uterine cytosol; MPA competed with progesterone in a similar fashion in both rat and rabbit. These data demonstrate a distinct species difference in the competitive nature of MPA for the glucocorticoid receptor but not for the progestin receptor. The results suggest that MPA, or possibly a metabolite, may be teratogenic in rabbits by binding with specific glucocorticoid receptors to inhibit or alter normal steroidal function in embryo-fetal development.     

Radioimmunoassay of serum medroxyprogesterone acetate (Provera) in women following oral and intravaginal administration.

A radioimmunoassay (RIA) method for measuring medroxyprogesterone acetate (MPA, Provera) in serum has been developed utilizing benzene:iso-octane extraction, 3H-MPA to assess procedural losses, goat anti-MPA-3-(0-carboxymethyl) oxime-bovine serum albumin serum and dextran-coated charcoal separation. Control serum blanks were undetectable, 200 pg/ml of MPA was measurable with a high reliability, and intra- and interassay coefficients of variation were 6 and 13 percent, respectively. MPA added to control serum was quantitatively recovered. Serum MPA levels measured in 2 women after ingestion of 10 mg MPA rose to 3.4 to 4.4 ng/ml within 1 to 4 hours after oral intake and fell rapidly thereafter to 0.3 to 0.6 ng/ml within 24 hours. Insertion of Silastic intra-vaginal rings (IVRs), containing 100 or 200 mg of MPA, into 4 women for periods of 3 weeks resulted in a rapid rise of serum MPA after insertion, rather stable MPA levels of 0.9 to 1.6 ng/ml while the IVRs were in place, and a rapid decline of serum MPA following IVR removal. Serum estradiol-17beta and progesterone concentrations, measured about 3 times a week in these patients, indicated that ovulation was consistently inhibited. The serum MPA levels observed in this study were approximately 5 times lower than those reported by other investigators using a double-antibody RIA of MPA in unextracted serum.     

Zinc status of women with low bone mineral density who receive calcium supplements

We evaluated whether a daily high-dose calcium supplement perturbs the zinc status in 23 postmenopausal women (mean age: 63yr) with low bone mineral density. Plasma and erythrocyte zinc concentrations, plasma bone-specific alkaline phosphatase (BSAP) and 5′-nucleotidase activities, and urinary zinc and calcium excretion were determined first at the end of 4 wk of daily oral calcium (1200 mg) and were measured again at the end of the subsequent 4 wk of daily cosupplementation with calcium (1200 mg) and zinc (30 mg). Mean plasma and erythrocyte zinc concentrations after 4 wk of calcium alone were not significantly different from concentrations after cosupplementation of calcium and zinc. Mean plasma BSAP activities before cosupplementation with zinc was significantly higher than that after zinc (p<0.02), whereas plasma 5′-nucleotidase activities were not affected by zinc supplementation. Urinary zinc excretion slightly, but significantly, increased after the supplementation of zinc (p<0.05), whereas calcium excretion remained similar. Our data indicate that a 4-wk zinc supplementation did not significantly improve zinc status. Although limited by the small sample size and short study duration, our data suggest that a daily calcium dose of 1200 mg had no effect on the zinc status of our subjects.     

The metabolic fate of medroxyprogesterone acetate in the baboon.

The metabolic fate of medroxyprogesterone acetate (6alpha-methyl-17a lpha-acetoxyprogesterone; MAP)was studied in intact baboons and in those with bile fistulas. The steroid moiety was labeled with tritiated hydrogen at positions 1 and 2 and the 17alpha-acetate with carbon-14, thus affording the opportunity to ascertain the loss of the 17-acetoxy group and the fate of both labels. Following the iv administration of labeled MAP only a small percentage (less than 15%) of the administered dose was recovered in the urine in 7 hours in intact baboons, as well as in the urine of baboons with biliary fistulas. Higher amounts of radioa ctivity were excreted in the bile (approximately 25%), amounting to almost double the percentage excreted into the urine. The similarity in the urinary excretion of radioactivity in intact and biliary fistula animals indicates that, even though a substantial biliary excretion of the labeled MAP occurred, the amount involved in an enterohepatic circulation is probably small. Glucosiduronates were the predominant conjugates, both in the urine and bile. The loss of the 17alpha-acetate group appeared to be rather extensive, ranging 30-70% among different co njugated and unconjugated metabolities of MAP. The degree of in vivo hydrolysis of the axial 17alpha-acetate of MAP, though extensive appeared to be of a significantly lesser magnitude than that exhibited toward the equatorial 3beta and 17beta acetate groups of labeled ethynodiol diacetate injected into baboons. The deacetylation of the 17alpha-acetate in MAP was similar to that observed in humans given the drug. Oxygenation of MAP at positions 1 and/or 2 appeared to be rather minimal (less than 5%).     

The effect of medroxyprogesterone acetate on bone marrow and testis during cytotoxic chemotherapy

The effect of medroxyprogesterone acetate (MPA) on the mitotic activity of bone marrow and testis during chemotherapy was investigated experimentally in an animal study. A total of 120 male Swiss albino mice were included in this study. Six groups were formed, each consisting of 20 mice. Low-dose MPA (LD-MPA) (15 mg/kg), high-dose MPA (HD-MPA) (100 mg/kg), LD-MPA plus cyclophosphamide (CP) (65 mg/kg), HD-MPA plus CP (65 mg/kg), and CP (65 mg/kg) were administered to the test groups and no drug was administered to the control group. Bone marrow samples and testis were examined for mitotic activity rate (MAR) on days 0, 18, 22, 26, and 30. In groups with regimens containing CP, MAR of hematopoietic cells in bone marrow was suppressed significantly (p<0.05). There was no difference in MAR of hematopoietic cells in bone marrow between the groups given MPA or not (p>0.05). Mitotic activity rate of the testis cells was significantly suppressed in groups with regimens containing MPA (p<0.05). In conclusion, MPA inhibited mitotic activity of testis, but there was no effect on the mitotic activity of bone marrow. These data do not seem to confirm the hypothesis of a myeloprotective effect of MPA. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reproductive hormones and bone mineral density in women runners.

We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners.     

Effects of medroxyprogesterone acetate on gestation in mink

Mink ovariectomized 14 days after the first of two matings received injections of 2 mg MPA, the same MPA treatment + an oestradiol-17 beta implant or no replacement therapy. Some mink were ovariectomized after implantation and given a single dose of 2 mg MPA or no replacement therapy. MPA persisted in the serum at detectable levels for 13 or more days in all mink treated. MPA and MPA + oestradiol induced uterine growth but neither treatment was capable of inducing embryo implantation. More embryos were retained in mink treated with MPA alone and these appeared to be viable. Implanted embryos persisted for a longer period in animals that were ovariectomized and treated with MPA. MPA neither supported pregnancy nor permitted parturition. Serum LH was elevated by 1 week after ovariectomy and elevations persisted for a further 20 or more days. While MPA alone had no apparent negative feedback effects on LH, animals that received MPA + oestradiol did not display any elevation of LH, suggesting that oestradiol or a combination of MPA and oestradiol has a potent negative feedback in mink.     

Some effects of medroxyprogesterone acetate on intermediary metabolism in rat liver.

This study examines the effects of MPA (medroxyprogesterone acetate) on some of the hepatic enzymes of carbohydrate and lipid metabolism in the rat, and compares these with the effects of cortisol and saline. Levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH) were also measured. Intact mature female Wistar rats with average initial weight of 200 gms were injected with MPA (mO mg/kg IM) once a week for 4 weeks and were sacrificed 3 to 5 days after the last injection. Hydrocortisone (Solu-Cortef [R]) 40 mg/kg IM were given to cortisol-treated animals twice daily for 7 days. The animals were sacrificed 2-4 hours after the last dose was given. Normal saline (0.2 mg. IM) was injected in control animals twice a day. The method of Jellinek, Amako, and Willman was used to analyze NADPH. Liver samples were assayed for various enzymatic activities such as phophofructokinase (PFK); pyruvate kinase (PK), glycerol-3-phosphate dehydrogenase (G3PD), "malic" enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PD). The methods of Colowick and Kaplan were used in enzymatic analyses. Lipogenic stimulation by MPA is indicated by increased levels of G3PD and ME, both of which are implicated in lipogenesis, as well as by NADPH. PFK, PK, and G6PD were all unaffected by the MPA regimen, suggesting that elevation of ME and NADPH activities may reflect increased amino acid conservation. The enzymatic pattern of MPA treatment shows lipogenesis and protein conservation, while that of cortisol regimen shows significantly lower levels of ME, G3PD, and PRK.     

Estrogen, medroxyprogesterone acetate, endothelial function, and biomarkers of cardiovascular risk in young women

Medroxyprogesterone acetate (MPA) is widely known for its use in combination hormone therapy for postmenopausal women. However, MPA is also commonly used in young women for contraception and treatment of a number of gynecological conditions. Despite its widespread use, the cardiovascular effects of MPA in young women are unclear. Therefore, the purpose of this study was to determine the acute effects of MPA when used in combination with estradiol on markers of cardiovascular risk in young women. We suppressed endogenous estrogens and progesterone in 10 premenopausal women using a gonadotropin-releasing hormone antagonist (GnRHa) for 10 days. On day 4 of GnRHa subjects received 0.1 mg of estradiol (GnRHa+E(2)), and on day 7 5 mg of MPA was added (GnRHa+E(2)+MPA). Endothelium-dependent vasodilation and endothelium-independent vasodilation of the brachial artery, lipids, homocysteine, high-sensitivity C-reactive protein, and endothelin-1 were assessed during treatment with GnRHa, GnRHa+E(2), and GnRHa+E(2)+MPA. Four additional subjects were tested to validate the efficacy of the GnRHa model and confirm the findings. Endothelium-dependent vasodilation was greater during GnRHa+E(2) than during GnRHa or GnRHa+E(2)+MPA (P = 0.006). Endothelin-1 was lower during GnRHa+E(2) than GnRHa alone (P = 0.039). Endothelin-1 increased with the addition of MPA and was not significantly different from GnRHa alone. There were no differences in the other markers of cardiovascular risk between hormone treatment days. These data suggest that acute MPA administration negates the beneficial effects of estradiol on endothelium-dependent vasodilation in young women. In addition, these data suggest that estradiol decreases endothelin-1 concentrations and the addition of MPA may counteract the effect of estradiol on endothelin-1.     

Teratogenic effects of cyproterone acetate and medroxyprogesterone treatment during the pre- and postimplantation period of mouse embryos. II. Cyproterone acetate and medroxyprogesterone acetate treatment before implantation in vivo and in vitro

The study was performed to investigate direct embryotoxic effects of maternal progestin treatment during the preimplantation period. In the first experiment pregnant mice received a single subcutaneous injection of either cyproterone acetate (CA) or medroxyprogesterone acetate (MPA) on day 2 of pregnancy (5-600 mg/kg). In a second experiment four-cell embryos were exposed to CA or MPA in vitro (3 or 30 micrograms/ml medium). Our results revealed: (1) After maternal treatment the number of live embryos was reduced after the highest CA dose. Development into blastocysts was inhibited in a dose-related manner after CA but not after MPA. The number of cells in morulae, blastocysts, and of the inner cell mass (ICM) of late blastocysts was not affected. (2) When morulae and blastocysts were cultured in vitro after maternal treatment, hatching, attachment, and trophoblast outgrowth were inhibited after high doses, but development and differentiation of the ICM were inhibited even after low doses. (3) Application of 30 micrograms/ml of CA or MPA in vitro was directly embryolethal. Three micrograms/ml did not affect development into blastocysts, but ICM development and differentiation were again inhibited during subsequent culture in hormone-free medium. (4) Qualitative protein synthesis was altered in morulae and blastocysts 24 hours after maternal CA treatment. According to our results high doses of progestins are embryotoxic before implantation, low doses have delayed effects on embryonic development that are particularly evident after implantation in vitro.     

Adiponectin is associated with bone mineral density in perimenopausal women.

The aim of the current investigation was to investigate any potential effect of fasting plasma adiponectin concentration on bone tissue, and to find possible relationships of fasting plasma adiponectin level with different body composition, insulin sensitivity and physical performance parameters in a group of healthy perimenopausal women. Twenty-one premenopausal and 17 early postmenopausal women participated in this study. The women were matched for body mass index (BMI) and level of mean daily energy expenditure. Women had similar adiponectin (8.4 +/- 3.9 vs. 9.9 +/- 5.4 microg/ml) and leptin values (12.0 +/- 7.7 vs. 14.0 +/- 8.2 ng/ml) before and after menopause. Significant relationships were observed between plasma adiponectin and bone mineral content, total bone mineral density (BMD) and lumbar spine BMD values (r > - 0.36; p < 0.05). Furthermore, adiponectin had a significant negative association with total BMD (beta = - 1.228; p = 0.004) and lumbar spine BMD (beta = - 0.312; p = 0.005) independent of the influence that other measured body compositional, hormonal or physical performance factors may exert on BMD. Adiponectin was also significantly related to waist-to-hip ratio (WHR) (beta = - 2.300; p = 0.002) and fasting insulin resistance index (FIRI) (beta = - 0.006; p = 0.007) in separate regression models. No relationship was observed between leptin and measured bone, physical performance and insulin resistance values. Leptin significantly correlated to BMI (beta = 0.018; p = 0.034), lean body mass (beta = 0.025; p = 0.024) and fat mass (beta = 0.019; p = 0.001) in separate regression models. In conclusion, the results of present study show that circulating adiponectin appears to exert an independent effect on BMD in perimenopausal women and may represent a link between adipose tissue and bone mineral density.     

Radioimmunoassay for medroxyprogesterone acetate (Provera) using the 11alpha-hydroxy succinyl conjugate

The development of a radioimmunoassay for medroxyprogesterone acetate (MPA) employing rabbit antibodies made against a bovine serum albumin (BSA) conjugate of the hemisuccinate ester of 11alpha-hydroxy MPA are described. The 11alpa-hydroxyl group was introduced into MPA by a series of chemical and microbiological transformations. The acid succinate MPA was coupled to BSA by reacting it with N,N'-carbonyldiimidazole. Cross-reactivities of several MPA analogs were compared suing rabbit antisera developed against the C-11 conjugate of MPA and goat antiserum developed against a C-3 conjugate of MPA. Antibodies formed against the C-11 conjugate showed increased specificity to steroid analogs which changes in the C-21 side chain. The profiles of serum MPA levels vs time, measured with both the C-3 and C-11 antisera, after oral drug administration to the monkey were similar. After intramuscular drug administration to dogs, serum MPA levels measured with the C-3 antisera were consistently greater as compared with those with C-11 antisera. Factors affecting precipitation of the antibody-antigen complex, assay precision, and assay sensitivity were evaluated.     

Effect of low-repetition jump training on bone mineral density in young women.

The hypothesis of the present study was that low-repetition and high-impact training of 10 maximum vertical jumps/day, 3 times/wk would be effective for improving bone mineral density (BMD) in ordinary young women. Thirty-six female college students, with mean age, height, and weight of 20.7+/-0.7 yr, 158.9+/-4.6 cm, and 50.4+/-5.5 kg, respectively, were randomly divided into two groups: jump training and a control group. After the 6 mo of maximum vertical jumping exercise intervention, BMD in the femoral neck region significantly increased in the jump group from the baseline (0.984+/-0.081 vs. 1.010+/-0.080 mg/cm2; P<0.01), although there was no significant change in the control group (0.985+/-0.0143 vs. 0.974+/-0.134 mg/cm2). And also lumbar spine (L2-4) BMD significantly increased in the jump training group from the baseline (0.991+/-0.115 vs. 1.015+/-0.113 mg/cm2; P<0.01), whereas no significant change was observed in the control group (1.007+/-0.113 vs. 1.013+/-0.110 mg/cm2). No significant interactions were observed at other measurement sites, Ward's triangle, greater trochanter, and total hip BMD. Calcium intakes and accelometry-determined physical daily activity showed no significant difference between the two groups. From the results of the present study, low-repetition and high-impact jumps enhanced BMD at the specific bone sites in young women who had almost reached the age of peak bone mass.