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PubMedDate not supplied

[Morphological changes in the rat uterine tissues exposed to pregna-D'-pentaran derivatives of progestins and anti-progestins].

Changes in the uterus morphology of mature female rats were studied on the model of pseudopregnancy after treatment with the progestin 16 alpha,17 alpha-cyclohexanoprogesterone (PR) and the antirpogestins 5 alpha(H)-16 alpha,17 alpha-cyclohexano-4,5-dihydroprogesterone (APR1) and 5 beta(H)-16 alpha,17 alpha-cyclohexano-4,5-dihydroprogesterone (APR2). The rats were preliminarily estrogenized with 17 beta-estradiol at a dose of 1 microgram/(animal day) for 4 days and then treated with PR at a dose of 0.2 mg/(animal day) for 14 days. The first group was then left without any treatment, whereas APR1 and APR2 were injected at the dose of 0.2 mg/(animal day) for 4 days to the animals of the second and the third groups, respectively. Light and electron microscopy of the uterus preparations demonstrated that the PR action provoked a complete pseudopregnancy picture characterized by the endometrium functionalization and the myometrium hypertrophy. Subsequent treatment with APR1 and APR2 caused the hypertrophy to cease, which had a more pronounced effect in the case of APR1. At the same time, some indications of the endometrium functionalization remained observable after treatment with APR1 and APR2. The specific binding sites for 3H-labeled APR1 and APR2 were absent from the uterus cytosol for the rats gestagenized with PR.

Animals↗
PubMed1997

Responses of HDL subclasses, Lp(A-I) and Lp(A-I:A-II) levels and lipolytic enzyme activities to continuous oral estrogen-progestin and transdermal estrogen with cyclic progestin regimens in postmenopausal women.

Seventy postmenopausal women took part in the study. Subjects received either continuous oral 17 beta-estradiol 2 mg/day combined with norethisterone acetate 1 mg/day (E2/NETA, Kliogest) or transdermal treatment consisting of 28 day cycles with patches delivering 17 beta-estradiol 50 micrograms/day (Estraderm) combined with cyclic medroxyprogesterone acetate 10 mg/day (E2/MPA, Provera), on days 17-28. At baseline the serum lipid and lipoprotein concentrations, composition and concentrations of high density lipoprotein (HDL) subclasses, lipoprotein (Lp)(AI) and Lp(A-I:A-II) levels were comparable in the two groups. In the E2/NETA group, after 12 months hormone replacement therapy (HRT), the HDL2 cholesterol concentration decreased by 17% (P < 0.01) and the HDL3 cholesterol remained unchanged. The concentrations of HDL2b, HDL2a and HDL3a were reduced by 30, 26 and 15%, respectively, P < 0.001, and the cholesterol:triglyceride ratio decreased significantly in all HDL subclasses. Apolipoprotein (apo) A-I concentration decreased by 5% (P < 0.05), but apo A-II, Lp(A-I) and Lp(A-I:A-II) concentrations remained unchanged. In the E2/MPA group the HDL2 and HDL3 cholesterol levels were both reduced by 6% (P < 0.05) and the HDL3a, HDL3b and HDL3c concentrations decreased by 14, 12 and 17% during the E2/MPA phase compared with baseline (P < 0.01). No major changes in the composition of HDL subclasses occurred in the E2 MPA group during treatment. The apo A-I and Lp(A-I) levels were not changed, but apo A-II and Lp(A-I:A-II) concentrations decreased by 8 and 5%, P < 0.001 and P < 0.05, respectively. At 12 months the postheparin plasma hepatic lipase (HL) activity decreased only in the E2/NETA group (by 12%, P < 0.05). The cholesteryl ester transfer protein (CETP) activity was not affected by either HRT regimen. The results of our study show that the 2 HRT regimens have multiple effects on HDL particles and HRT induced changes in HDL are not associated with changes in activities of lipolytic enzymes or CETP.

Administration, Cutaneous↗
PubMed1996

Different effects of continuous oestrogen-progestin and transdermal oestrogen with cyclic progestin regimens on low-density lipoprotein subclasses.

Seventy-five postmenopausal women were randomly allocated to receive either continuous oral 17 beta-oestradiol 2 mg day-1 and norethisterone acetate 1 mg day-1 (E2/NETA) or transdermal treatment consisting of 28-day cycles with patches delivering 17 beta-oestradiol 50 micrograms day-1 combined with oral cyclic medroxyprogesterone acetate 10 mg day-1, on days 17-28 (E2/MPA). At baseline, the plasma lipid and lipoprotein concentrations, composition and concentrations of low-density lipoprotein (LDL) subclasses (LDL1, LDL2 and LDL3) isolated by density-gradient ultracentrifugation were similar in the two groups. The post-heparin plasma hepatic lipase activity (HL) correlated inversely with the percentage of total LDL found in LDL1 (buoyant LDL) and directly with the percentage of LDL found in LDL3 (dense LDL). After 12 months of hormone replacement therapy (HRT), the total and LDL-cholesterol concentration of the E2/ NETA group decreased by 14% and 17% respectively (P < 0.001), while in the E2/MPA group these parameters remained unchanged. The lowering of LDL-cholesterol in the E2/NETA group was a consequence of a significant reduction of the large, buoyant LDL particles (LDL1) from 103 mg dL-1 to 60 mg dl-1 (P < 0.001) and of a decrease of cholesterol content of LDL particles in the major LDL subclass, LDL2. In the E2/MPA group, the concentration of LDL1 decreased, but less than in the oral group. In both groups, a significant increase in the concentration of the LDL3 subclass was observed, indicating an overall shift to denser LDL particles. After 12 months, the post-heparin plasma HL activity decreased only in the E2/NETA group (by 12%). The inverse correlation between post-heparin plasma HL activity and LDL1 persisted in both groups, but the direct correlation between HL and LDL3 vanished in the E2/NETA group and subsided in the E2/MPA group. Our results indicate that HRT has multiple effects on LDL subclasses and suggest that these changes cannot be explained by changes in HL activity.

Body Mass Index↗
PubMed1992

Technetium- and rhenium-labeled progestins: synthesis, receptor binding and in vivo distribution of an 11 beta-substituted progestin labeled with technetium-99 and rhenium-186.

In an effort to develop radiopharmaceuticals useful for the diagnostic imaging of steroid receptor-positive breast tumors, we have radiolabeled an analog of the antiprogestin RU486 (mifepristone), modified to incorporate an N2S2 chelate system in the 11 beta-position, with 99Tc, 99mTc, and 186Re. For the 99Tc-labeled analogs (3), a syn pair and two individual antidiastereomers (linker methylene versus metal-oxo, relative to the N2S2 plane) were isolated. In competitive radiometric binding assays, the syn pair (3syn1,2) had affinity for the progesterone receptor that was 25% that of (promegestone) R5020 (or 161% that of progesterone), and the individual anti-diastereomers had affinities of 47% (3anti1) and 7% (3anti2) that of R5020 (or 303% and 45% that of progesterone). The specific-to-nonspecific binding ratio of the 99mTc (4) and 186Re (5) 11 beta-linked syn systems are 75/25 and 54/46, respectively. In vivo, conjugates 4 and 5 showed progesterone receptor-mediated uptake in rat uterus, but also high uptake in non-target tissues, presumably because of the high lipophilicity of the metal complexes. Modified systems may be useful in vivo as receptor-directed agents for diagnostic imaging or treatment of steroid receptor-positive tumors.

Animals↗
PubMedDate not supplied

Rationale for estrogen with interrupted progestin as a new low-dose hormonal replacement therapy.

OBJECTIVE: This review outlines the basic principles of a novel interrupted progestin hormone replacement therapy (HRT) regimen in which estrogen is given continuously but the progestin is administered in a 3-days-on and 3-days-off schedule. The rationale for this regimen is to prevent receptor down-regulation and allow estrogen to increase estrogen and progestin sensitivity during the progestin-free periods. METHODS: The reasons for poor patient acceptance of HRT are reviewed. The association of HRT with breast and endometrial cancer is discussed, as are the potential benefits of HRT on the skeleton and the cardiovascular system. Basic research studies in the rat are described that provide supporting evidence for the interrupted progestin regimen. Clinically, we review a pilot study examining symptom control, bleeding rates, and safety of the interrupted progestin regimen as well as preliminary results of the usefulness of this regimen for add-back therapy in GnRH agonist-treated patients. RESULTS: Estrogen and progestin receptor measurements in the rat uterus demonstrate a clear up- and down-regulation in response to estrogen and interrupted progestin but not to the continuous administration of estrogen and progestin or estrogen alone. In addition, we found a significant beneficial effect of a low-dose interrupted HRT regimen on bone mineral content and density in an aged rat model of osteopenia, compared with continuous estrogen and progestin or estrogen alone. These results support the hypothesis that the interrupted progestin HRT increases tissue sensitivity to both estrogen and progestin. Clinical studies demonstrated good symptom control, low bleeding rates, endometrial protection, and excellent patient acceptance. CONCLUSION: The combination of continuous estrogen with interrupted progestin appears to result in increased sensitivity to estrogen and progestin in estrogen-responsive tissues. As a result, lower doses of estrogen and progestin may be used for HRT with good biological effects. Further clinical studies, preferably in prospective randomized trials, are required to demonstrate reduced bleeding and improved patient acceptance of this new regimen compared to continuous combined HRT.

Animals↗