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[The mechanism of the therapeutic effect of norethisterone in hyperplastic diseases of the endo- and myometrium in women of reproductive age].

The paper is concerned with results of a study of clinico-biologic effect of a gestagen norsteroid drug--norcolut--on solitary and combined lesions of the endo- and myometrium. Four hundred and thirty-four patients of reproductive age with hyperplasia or polyps of the endometrium, uterine myoma, internal endometriosis or a combination of the pathologies were examined prior to administration of norcolut and during posttreatment cycle to evaluate the influence of the drug on the female reproductive system. Norcolut exerted the regulatory effect on the rhythm and pattern of menstruation and inhibited tumor growth. Also, changes in localization of myoma nodes, normalization of steroid hormone profile, decrease in the level of estradiol and progesterone receptors, and secretory transformation of the endometrium were observed. Those changes resulted in regression of endometrial lesions.

Adult↗

Simultaneous estimation of urinary steroids by semi-automated gas chromatography. Investigation of neo-natal infants and children with abnormal steroid synthesis.

Development of a method for multicomponent analysis of urinary steroids on open-tubular columns is described. The urinary steroid conjugates were hydrolysed enzymatically, extracted on Amberlite XAD-2 columns, purified on columns of Sephadex LH-20, then analysed as methyloxime trimethylsilyl ethers on a gas chromatograph on which up to 24 samples may be automatically injected. All major urinary steroids from 17-oxosteroids to cortisol metabolites were analysed and these were quantified relative to internal standards, 5alpha-androstane-3alpha, 17alpha-diol and cholesteryl butyrate added to the samples prior to derivatisation. The precision of the full technique and reproducibility of repetitive automatic solid injection was found to be acceptable for the purpose of profile analysis. Examples of urinary steroid profiles in normal infants and infants with disorders of adrenal steroid production and excretion are given.

Adrenal Gland Neoplasms↗

The value of urinary steroid analysis in chorionic neoplasia.

The profile of urinary neutral steroids was investigated in normal pregnancy and chorionic neoplasia by gas-liquid chromatography. The whole chramatogram was divided into three metabolically distinct fractions. The excretion of fraction 2, including four menstruation-dependent steroids (11-hydroxyandrosterone, 11-hydroxyetiocholanolone, pregnanediol, and pregnanetrial), was remarkably increased in normal pregnancy as compared with that in nonpregnant controls. But the same parameter was differentially reduced in hydatidiform mole (HM) and chorioadenoma destruens (CA) as compared with normal pregnancy, and the ratio of fraction 2 to fraction 1 (11-deoxy-17-ketosteroids) was found useful in separating normal pregnancy, HM, and CA from each other. In choriocarcinoma (CC), reduced excretion was observed in both fraction 1 and fraction 2 steroids. The linear relationship between the logarithm of fraction 2-fraction 1 ratio and that of pregnanediol excretion, as observed in the reproductive cycle of a healthy woman, was not detectable in women with CA, whose urine revealed a low value of log (fraction 2/fraction 1) in spite of an abundant HCG content. It is indicated that the above findings reflect the deficiency of ovarian steroidogenesis under the influence of abnormal HCG from tumors.

Adrenal Cortex Hormones↗

Excretion and measurement of estradiol and progesterone metabolites in the feces and urine of female squirrel monkeys (Saimiri sciureus).

The first objective of the present study was to determine the metabolic form and rate of excretion of ovarian hormone metabolites in the urine and feces of female squirrel monkeys injected with radiolabeled progesterone (Po) and estradiol. The major portion of the urinary metabolites of both hormones was excreted within 16-24 hr post-injection. Estrogen and Po isotopes in feces exhibited an excretion peak at 16 hr post-injection. The majority of recovered radiolabel of both hormones was excreted in feces. Chromatographic separation of fecal extractions indicated that the major estrogen metabolites in feces are in the free as opposed to the conjugated form. The radioactivity and immunoreactivity for estrone and estradiol (E(1) and E(2), respectively) in eluates of fecal samples subjected to celite co-chromatography indicated that both free E(1) and E(2) exist as excretion products in the feces of female squirrel monkeys. The major radioactive peaks for Po metabolites showed peaks in the elution profile at or very near the Po standard, and corresponded with the celite co-chromatography elution profile of Po standard when subjected to enzyme immunoassay (EIA). The second objective was to validate the application of EIA systems to measure fecal metabolites. Reproductive events of one female squirrel monkey across one annual reproductive cycle are described using the endocrine profile generated from fecal steroid assays. Examination of this profile confirmed that longitudinal fecal sampling and steroid hormone metabolite measurement in feces was not only feasible and practical, but accurately detected known reproductive events as well.

Animals↗

Plasma levels of C19 steroid glucuronides in pre-menopausal women with non-classical congenital adrenal hyperplasia.

Recent reports have thrown doubt on the role of measurements of plasma 5 alpha-androstane-3 alpha,17 beta-diol glucuronide (3 alpha-diolG) as a marker of peripheral androgen metabolism in women with polycystic ovarian syndrome and idiopathic hirsutism. It has been suggested that a plasma profile of C19 steroid glucuronides may be more informative. While preliminary data indicates that both 3 alpha-diolG and androsterone G (ADTG) may arise from adrenal steroid precursors, there have been no reports of C19 steroid glucuronides in women with non-classical, or late-onset congenital adrenal hyperplasia (NC-CAH), who constitute a significant proportion of the hirsute female population. We therefore measured plasma levels of 3 alpha-diolG, ADTG and dihydrotestosterone G (DHTG) before and following a standard Cortrosyn test in 15 symptomatic and 3 asymptomatic NC-CAH patients, 5 heterozygote carriers for 21-hydroxylase deficiency (NCHETS) and 18 normal women. The effects of chronic glucocorticoid (GCR) therapy (greater than 3 months) on the C19 steroid glucuronide profile in the symptomatic patients was also investigated. Baseline plasma levels of all 3 glucuronides were significantly (P less than 0.001) higher in symptomatic patients compared with either normals or NCHETS. However, the order of discrimination was ADTG greater than 3 alpha-diolG greater than DHTG. There were no significant differences between steroid glucuronide levels for NCHET and normal women and the C19 steroid glucuronide concentrations for the asymptomatic NC-CAH patients were greater than 2 SD above the normal means. Moderate clinical improvement was observed in all patients receiving oral GCR therapy and was accompanied by approx. 80% suppression of the plasma levels of all 3 C19 steroid glucuronides. This contrasts with a mean suppression of androstenedione of only 50%. However, plasma levels of the C19 steroid glucuronides were not significantly increased in response to a short ACTH stimulation test. This may be explained by the fact that the androgen glucuronides are thought to be peripherally formed metabolites derived from unconjugated glandular secreted androgen precursors and thus their synthesis at 60 min following adrenal stimulation may lag substantially behind that of their respective precursors. There were significant linear correlations between the levels of all 3 glucuronides, but neither correlated with Ferriman-Gallway scores, body mass index or 17-hydroxyprogesterone levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Hyperplasia, Congenital↗

Effect of steroids on nasal inflammatory cells and cytokine profile.

OBJECTIVES: To assess the cellular and humoral effects of unilateral topical steroid application on the nasal mucosa of chronic sinusitis patients. STUDY DESIGN: Cohort study with randomized grouping. METHODS: Chronic sinusitis patients awaiting endonasal sinus surgery were randomly divided into a study group and a control group. All patients underwent allergy studies and categorized as allergic or nonallergic. Patients in the study group were exposed unilaterally to fluticasone propionate nasal spray, 100 microg/day for 4 to 6 weeks before the planned surgery. The control group was not exposed to steroids. At the time of surgery, anterior ethmoid mucosa specimens were obtained. The samples were immunostained for CD3, MBP, CD68, elastase, and tryptase. In situ hybridization was used for the detection of interleukin (IL)-4, IL-5, and interferon gamma (IFN-gamma) mRNA. The results were compared between the treated and untreated sides of exposed patients, as well as with nontreated controls. RESULTS: Twenty-one patients consented to participate in the study. The number of CD3-, MBP-, and tryptase-positive cells was significantly less in the treated and untreated sides of exposed patients, compared with unexposed controls. IL-4 and IL-5 mRNA were significantly downregulated in the treated side of allergic patients, as compared with nontreated patients. This effect could not be shown for IL-4 in nonallergic patients. CONCLUSIONS: Topical steroid therapy had an anti-inflammatory effect on both allergic and nonallergic chronic sinusitis patients. The unilateral application of the steroid spray affected the contralateral side as well.

Administration, Intranasal↗

Pregnanolone isomers, pregnenolone and their polar conjugates around parturition.

The levels of four pregnanolone isomers and their polar conjugates and pregnenolone sulfate were measured in the plasma of 13 and 7 women at delivery with subarachnoidal and epidural analgesia, respectively, and in corresponding samples of umbilical plasma using a simple quadrupole GC/MS system with electron impact ionization (pregnenolone isomers), RIA following HPLC separation (pregnenolone) and specific RIA (pregnanolone sulfate). The concentration of epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one) in both maternal and umbilical plasma was much lower than that of other pregnanolone isomers. The levels of 3beta-hydroxy-pregnanolone isomers were significantly higher in the umbilical plasma than in the maternal, while the differences in 3alpha-hydroxy-isomers were insignificant. The differences in conjugates were insignificant with the exception of allopregnanolone, the levels of which were lower in umbilical plasma. In all the pregnanolone isomers, a significantly lower conjugated/unconjugated steroid ratio was found in the umbilical plasma than in the maternal plasma. In addition, time profiles of the steroids were measured around parturition and in the postpartum period in the maternal serum. Similarly, the levels of polar conjugates of all pregnanolone isomers were followed during parturition. Changes in concentrations of free steroids exhibited a similar pattern, with a fall primarily within the first hour after delivery. The decrease in conjugated steroids was shifted to the interval within the first hour and first day after delivery, and the changes were more pronounced. The time profiles of the conjugated/free steroid ratio exhibited a significant decrease within the first hour and the first day after delivery in all of the isomers investigated. A decrease was also observed in the ratio of 3alpha/3beta-isomers and 5alpha/5beta-isomers around parturition. The possible physiological consequences of the findings are indicated.

Female↗

Effect of egg deprivation on sex steroids, gonadotropin, prolactin, and growth hormone profiles during the reproductive cycle of the mouthbrooding cichlid fish Oreochromis niloticus.

Various hormones were analyzed during the course of a reproductive cycle in the cichlid fish Oreochromis niloticus: plasma levels of the gonadal steroids 17beta-estradiol (E2), testosterone (T), 17, 20beta-OH progesterone (17,20beta-P), gonadotropin (taGtH), and plasma and pituitary concentrations of prolactin (tiPRL(I) and tiPRL(II)) and growth hormone (tiGH). Two categories of fish were sampled and sacrificed on days 1 and 3 postspawning and at 3-day intervals thereafter: typical incubating females (INC), and nonincubating females (NI), deprived of their eggs just after spawning. Such deprivation is known to suppress maternal behavior and to accelerate ovarian development and especially vitellogenesis, thus shortening the mean interspawning interval. In both groups, variations of the plasma concentrations of E2 and T appeared to depend on ovarian stages, and differences between groups appeared to reflect underlying differences in the kinetics of ovarian development. The observation of noticeable levels of 17,20beta-P in plasma before spawning, when high values of taGtH could also be detected in NI females, suggests the implication of this progestin in the control of final maturation events, as in some other teleosts. Moreover, 17,20beta-P, which was still detected a few days after spawning, but at low concentrations and only in the plasma of INC females, might play a role at the beginning of the reproductive cycle in incubating females (maternal behavior and/or slowing down of ovarian growth). The pituitary and plasma profiles of both tiPRLs isoforms appeared to depend mainly on the kinetics of ovarian development in each group of fish, suggesting a role during the beginning of vitellogenesis. However, the variance of plasma tiPRL(II), which was significantly enhanced during maternal behavior in INC females, also suggests an implication of this hormone in the control of that behavior. Concerning tiGH, comparison of the plasma profiles in INC and NI fish also suggest an influence on the control of maternal behavior, but a main effect of starvation of INC during mouthbrooding cannot be excluded.

Animals↗

Group separation and gas chromatography--mass spectrometry of conjugated steroids in plasma.

A method is described for analysis of metabolic profiles of conjugated steroids in plasma. Steroids are extracted by Amberlite XAD-2 or Sep-Pak C18 cartridges at 60 64 C in the presence of triethylamine sulphate and separated into unconjugated neutral and phenolic compounds, glucuronide, monosulphate and disulphate conjugate groups by chromatography on the lipophilic strong anion exchanger triethylaminohydroxypropyl Sephadex LH-20 (TEAP-LH-20). The conjugate moiety is hydrolyzed by brief enzymatic or solvolytic procedures and released steroids are separated into a neutral and a phenolic fraction on TEAP-LH-20. The O-methyloxime and trimethylsilyl ether derivatives of the steroids are analyzed by glass capillary column gas liquid chromatography and gas chromatography mass spectrometry. Examples of the application of the method to analysis of conjugated steroids in plasma from pregnant women are given.

Chromatography, Ion Exchange↗

Variations in urine excretion of steroid hormones after an acute session and after a 4-week programme of strength training.

Performing strength exercise, whether acutely or in a training programme, leads to alterations at the hypothalamic-pituitary-testicular and hypothalamic-pituitary-adrenal axes. One way to evaluate these changes is by analysis of the excretion of steroid hormones in the urine. The present study determined the variations in the urine profile of glucuroconjugated steroids after a single session of strength exercise and after a 4-week programme of strength training. The subjects were a group (n = 20) of non-sportsman male university students who worked out 3 days a week [Monday (M), Wednesday (W) and Friday (F)], performing the exercises at 70-75% of one repetition maximum strength (1-RM). Four urine samples were collected per subject: (A) before and (B) after a standard session prior to initiating the training programme, and (C) before and (D) after the same standard session at the end of the study, and they were assayed by gas chromatography coupled to mass spectrometry. The concentrations of the different hormones were determined relatively to the urine creatinine level (ng steroid/mg creatinine) to correct for diuresis. After the exercise sessions, both before and after the training programme, there was a fall in the urine excretion of androgens and estrogens, but no statistically significant changes in the excretion of tetrahydrocortisol (THF) and tetrahydrocortisone (THE). The anabolic/catabolic hormones ratio also decreased after the acute session, although only androstenodione + dehydroepiandrosterone (DHEA)/THE + THF ratio had a significant decrease (P < 0.05). After the training programme, there was a significant (P < 0.01) improvement in the strength of the muscle groups studied, and an increased urinary excretion of all the androgens with respect to the initial state of repose, with the difference being significant in the case of epitestosterone (Epit) (P < 0.05). The androsterone (A) + etiocholanolone (E)/THE + THF ratio increased significantly (P < 0.05) concerning the initial state. We therefore conclude that subjects suffer variations of the urine profile with regard to the steroid hormones before and after the acute strength sessions and after the training period. The alteration after the training programme seems to be due to the subjects' hypothalamic-hypophysis-testicular and hypothalamic-pituitary-adrenal axes adaptations, which enable them to increase physical strength.

Adrenal Cortex Hormones↗

Narcissism and empathy in steroid users.

OBJECTIVE: In an effort to begin to construct a psychological profile of anabolic steroid users, the authors compared weight lifters and bodybuilders who did or did not use anabolic steroids on an objective measure of narcissism and on clinical ratings of empathy. METHOD: The subjects were 16 weight lifters and bodybuilders who reported that they had used anabolic steroids within the past year and a comparison group of 20 weight lifters who had not used steroids. The Narcissistic Personality Inventory and clinical ratings of empathy were used to assess narcissism. RESULTS: Steroid users had significantly higher scores on dimensions of pathological narcissism and significantly lower scores on clinical ratings of empathy. CONCLUSIONS: These preliminary results document a relationship between anabolic steroid use and narcissistic personality traits. They also indicate the need for further research to determine whether narcissistic personality traits contribute to the initiation of anabolic steroid use or result from their use.

Adult↗

Effects of sex steroids on components of the insulin resistance syndrome in transsexual subjects.

OBJECTIVE: Sex differences are found in most components of the insulin resistance syndrome and the associated cardiovascular risk profile. These differences are attributed to sex-specific sex steroid profiles, but the effects of sex steroids on the individual components of the insulin resistance syndrome remain incompletely understood. DESIGN: Prospective, intervention study. SUBJECTS: In 37 young (age range 16-36 years), nonobese [body mass index (BMI) < 29], transsexual subjects, effects of ethinyl oestradiol (100 micro g/day) + cyproterone acetate (100 mg/day) administration were evaluated in 20 male-to-female transsexuals and of testosterone-ester administration [250 mg intramuscularly (i.m.)/2 weeks] in 17 female-to-male transsexuals. MEASUREMENTS: We studied lipid spectrum, postheparin hepatic lipase (HL) and lipoprotein lipase (LPL) activity, blood pressure, glucose utilization (by euglycaemic hyperinsulinaemic clamp), and fat areas (by magnetic resonance imaging) at baseline and during 1-year cross-sex hormone administration. RESULTS: Oestrogens + antiandrogens increased high-density lipoprotein (HDL)-cholesterol and decreased LDL-cholesterol, and HL activity, which are considered beneficial. But this combination also increased triglycerides, blood pressure, subcutaneous fat and visceral fat, and decreased the LDL-particle size, LPL activity and insulin sensitivity, which are all considered detrimental. Testosterone reduced HDL-cholesterol and the LDL-particle size, and increased triglycerides and HL activity. An android fat distribution was induced (i.e. decreased subcutaneous and increased visceral fat). Blood pressure, total and LDL-cholesterol, LPL activity and insulin sensitivity were mainly unaffected. CONCLUSIONS: The effects of cross-sex hormone treatment - in the dosages used in this study - in healthy, nonobese, young transsexual subjects do not show unequivocally that female sex steroids, given in large amounts to male subjects, have beneficial effects on cardiovascular profile and that high dose testosterone administration to female subjects is detrimental with respect to cardiovascular risk.

Adipose Tissue↗

Preovulatory dynamics of Steroids Demonstrated in vivo by Ovarian Follicles of Cyclic and Superovulated Rat Females.

The destiny of individual follicles, especially their growth and atresia, appears to be directly related to particular steps of steroid metabolism. Since the superovulatory treatment results in insufficiently documented changes in follicular steroid levels, it was decided to search for detailed profiles of these steroids and then to compare them with these of regularly cycling females. Thus, the preovulatory follicles were isolated from superovulated immature and intact mature female Wistar rats. Mature females with regular 4-day estrous cycle were sacrificed consecutively every 2 or 3 h on the day of pro-estrus. Immature (24 day old) females were injected with PMSG (30 IU) and 56 h later with hCG (20 IU) and sacrificed at 0, 24, 48 and 56 h, and then every 2 or 3 h until 72 h after the PMSG treatment. In both animal models isolated follicles were homogenized and then the concentration of estradiol, androgen and progesterone was estimated by RIA. The follicles of cycling and PMSG/hCG injected rats showed different dynamics of steroid contents. Nevertheless, in both models a peak of androgen content appeared a few hours earlier than that of progesterone. During the progesterone peak or immediately after that a sharp fall in androgen content was found which was followed by a decrease in estradiol concentration. The follicles of superovulated rats contained lower amounts of estradiol, progesterone and especially of androgens which were much lower than these in the follicles of cyclic rats. In PMSG/hCG-derived preovulatory follicles the predominance of androgens over estradiol was maintained longer than in the follicles developing during physiological estrous cycle. These results suggest that the PMSG/hCG model of superovulation is marked by the induction of massive follicular atresia. Therefore, neither morphological nor biochemical alterations observed in PMSG/hCG-derived ovarian follicles should be considered as fully physiological changes.

Journal Article↗

Delayed puberty in males with beta-thalassemia major: pulsatile gonadotropin-releasing hormone administration induces changes in gonadotropin isoform profiles and an increase in sex steroids.

Patients with beta-thalassemia major often have pubertal delay, the etiology of which has not been fully elucidated. We investigated the pituitary-gonadal response to short-term subcutaneous pulsatile gonadotropin-releasing hormone (GnRH) administration (150 ng/kg body weight every 120 min for 7 days) in five young males (aged 13.6-19.0 years) affected by beta-thalassemia major and presenting signs of delayed puberty. Immunoreactive and bioactive gonadotropin levels were determined and their isoform profiles were examined, before and after GnRH treatment, in a pool of samples collected every 15 min for 240 min. Testosterone, androstenedione, 17-hydroxyprogesterone, dehydroepiandrosterone and 17 beta-estradiol were measured as markers of gonadal function on days 0, 1, 3, 5 and 7 of treatment. Five patients (aged 16.9-26.8 years) with confirmed diagnosis of idiopathic hypogonadotropic hypogonadism who were starting pulsatile GnRH therapy were also studied in the same protocol. Increased sex steroid levels were observed in both groups as a result of treatment. On day 7, the thalassemic patients had increased bioactive luteinizing hormone (LH) and follide-stimulating hormone (FSH), although immunoreactive LH and FSH were comparable to day 0. Moreover, fewer acidic and more basic immunoreactive and bioactive isoforms were noted in LH profiles on day 7. Similar results were observed in hypogonadal patients, who also had increased immunoreactive LH and FSH values. We suggest that the early stage of delayed puberty in thalassemia might be characterized by a neuroendocrine dysfunction resulting in an impaired hypothalamic GnRH release, which is inadequate for a proper pituitary stimulation. Pulsatile GnRH treatment seems to re-establish partially the correct pituitary-gonadal function.

17-alpha-Hydroxyprogesterone↗

Urodynamic studies in the normal menstrual cycle: the relationship between hormonal changes during the menstrual cycle and the urethral pressure profile.

The influence of endogenous gonadal steroids on the urethral pressure profile (UPP) was studied in 27 healthy nulliparous women with the normal ovulatory cycles. The UPP and hormonal values were recorded in the follicular phase, at midcycle, and early and late in the luteal phase. Simultaneous urethrocystometry was performed by means of the microtransducer technique, according to a precise standardized methodology. The parameters of the UPP, as defined by the Standardization Committee of the International Continence Society, and the area under the urethral closure pressure curve (integrated pressure) were calculated. Reproducibility of the UPP measurements was evaluated. In addition to a basal body temperature (BBT) chart, serum levels of 17 beta-estradiol (E2), progesterone (P), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin were measured at each study session in order to confirm a normal ovulatory pattern for that cycle and for comparison with the urodynamic parameters. The mean values and standard deviation of the UPP parameters in healthy nulliparous women in the supine and sitting positions are presented. Values of the pressure measurements obtained during one menstrual cycle did not change systemically with the hormonal alterations. At midcycle and early in the luteal phase, however, and anatomic and functional lengths of the urethra were consistently increased over those found in the early follicular and late luteal phases. The data suggest a causal relationship between the changes in serum E2 concentrations and the changes in urethral length.

Adult↗

Abnormal steroid excretion in gestational trophoblastic disease complicated by ovarian theca-lutein cysts.

Serum and urine steroids were examined in two subjects with trophoblastic disease accompanied by large ovarian theca-lutein cysts and compared with those from 10 patients with trophoblastic disease but without palpable cysts. In the patients without cysts normal values were obtained for serum oestradiol, progesterone, 17 alpha-hydroxyprogesterone and androstenedione, and for urinary total oestrogens, pregnanediol, pregnanetriol, and 17-oxosteroids. Nineteen urinary steroid metabolites, quantified by capillary gas-liquid chromatography, were either within reference limits or marginally raised. In several cases relatively minor increases in serum testosterone and cortisol and urinary free cortisol were observed. In contrast, the subjects with cysts showed pronounced excesses of androgen metabolites, 17 alpha-hydroxypregnenolone, pregnanediol, and pregnanetriol, and both exhibited a similar pattern of unusual additional metabolites. The profiles superficially resembled those seen in 21-hydroxylase deficiency adrenogenital syndrome, but there were important discrepancies reflecting known differences in ovarian and adrenal steroid metabolism. Chemotherapy led to decline of human chorionic gonadotrophin concentrations, regression of the cysts, and return to normal of the steroid profile. Excess steroids in the patients with cysts may have originated in the ovary rather than in the trophoblastic tissue.

Adult↗

Tibolone, a steroid with a tissue-specific hormonal profile, completely prevents ovariectomy-induced bone loss in sexually mature rats.

Tibolone (Org OD 14) is a synthetic steroid with combined estrogenic, progestagenic, and androgenic properties and behaves as a tissue-specific steroid. In the current study, we determined the effects of a 4-week treatment with different doses of tibolone on estrogen deficiency-induced bone loss in mature 3-month-old rats. As a reference, 17alpha-ethinyl estradiol (EE2) was used. The frequency of administration, once or twice a day, was also studied. Bone parameters were determined in sham operated controls, ovariectomized (OVX) controls and OVX-treated rats. Bone loss was assessed by peripheral quantitative computed tomography directly and by quantitative Roentgen densitometry after defatting to exclude influence of fat changes. Femoral bone geometric parameters, plasma osteocalcin level, and urinary deoxypyridinoline/creatinine ratio were also determined. Ovariectomy caused a significant decrease in trabecular bone mineral density in the distal metaphyseal part of the femur using both methods, whereas no change in cortical bone density was found. Trabecular bone loss was prevented in a dose-dependent manner by tibolone (250, 1000, and 4000 microgram/rat/day) when given once or twice daily. EE2 also prevented trabecular bone loss but its efficacy was dependent upon the frequency of dosing. Both tibolone and EE2 induced a significant reduction in the urinary deoxypyridinoline/creatinine ratio and plasma osteocalcin level. Tibolone and EE2 had no effect on other femoral bone parameters except a reduction in femoral length. In conclusion, treatment with tibolone for 4 weeks prevented OVX-induced bone loss by suppressing both bone resorption and bone turnover in a similar way as EE2. However, the frequency of dosing is more important for EE2 than for tibolone. Tibolone acts in this animal model for postmenopausal bone loss as an estrogen agonist on bone.

Anabolic Agents↗