Adaptive reactions of the endocrine system of children living under conditions of contrasting photoperiods

Age-related changes in the levels of pituitary, thyroid, and sex hormones and their dependence on the day length were studied in 242 healthy 10-to 16-year-old boys born and permanently living in the southern part of Arkhangel’sk oblast. It was found that the serum levels of thyroid hormones, gonadotropins, and sex steroids underwent circannual changes. The minimum concentrations of thyroxine, testosterone, and estradiol and the maximum concentrations of triiodothyronine, lutcinizing and follicle-stimulating hormones, and progesterone were associated with the shortest days. In contrast, the longest days were associated with the maximum concentrations of thyroxine, testosterone, and estradiol and the minimum concentrations of triiodothyronine, luteinizing and follicle-stimulating hormones, and progesterone. A factor dependence of the thyroxine, triiodothyronine, testosterone, estradiol, and prolactin concentrations on the day length was found in the group examined. This dependence was more pronounced during the second half of adolescence.     

四眼斑水龟血浆生殖激素季节性变化

为了进一步探讨四眼斑水龟(Sacalia quadriocellata)的繁殖生理周期和生殖激素分泌特征,使用放射免疫分析测定法(RIA)分别测定了8月(夏季)、10月(秋季)、1月(冬季)、3月(春季)四眼斑水龟血浆中卵泡刺激素(FSH)、促黄体生成素(IJH)、睾酮(T)、雌二醇(E2)、孕酮(P)五种生殖激素的含量.结果显示,四眼斑水龟生殖激素分泌呈现较明显的周期性,激素水平与环境温度的变化有关;雄性T含量夏季开始升高,秋季达到高峰,与精子的发生和成熟同步;雌性T水平升高促进其接受雄性爬胯,且作为雌激素合成的前体物质,间接作用于雌激素的合成;排卵会出现LH峰,E2含量排卵前几个月开始增长,刺激肝生成卵黄;排卵期间P含量较高,可能在排卵过程中发挥作用.     

The Influence of Sex Steroids on Structural Brain Maturation in Adolescence

Puberty reflects a period of hormonal changes, physical maturation and structural brain reorganization. However, little attention has been paid to what extent sex steroids and pituitary hormones are associated with the refinement of brain maturation across adolescent development. Here we used high-resolution structural MRI scans from 215 typically developing individuals between ages 8–25, to examine the association between cortical thickness, surface area and (sub)cortical brain volumes with luteinizing hormone, testosterone and estradiol, and pubertal stage based on self-reports. Our results indicate sex-specific differences in testosterone related influences on gray matter volumes of the anterior cingulate cortex after controlling for age effects. No significant associations between subcortical structures and sex hormones were found. Pubertal stage was not a stronger predictor than chronological age for brain anatomical differences. Our findings indicate that sex steroids are associated with cerebral gray matter morphology in a sex specific manner. These hormonal and morphological differences may explain in part differences in brain development between boys and girls.     

A levels of endogenous gonadal hormones and their relationship with selected coronary artery disease risk factors among young women post myocardial infarction

In recent decades a significant raise in the incidence of myocardial infarction among young women has been recorded. It is presumed that, apart from the classical risk factors, other reasons exist for premature atherosclerosis in young women, related to the homeostasis of gonadal hormones. The aim of the study was to analyze the levels of gonadal hormones (estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone, testosterone and dehydroepiandrosterone) measured in the luteal phase, in 65 normally menstruating women post myocardial infarction (MI) and to investigate a possible relationship between the hormone profile and selected coronary artery disease (CAD) risk factors. The levels of gonadal hormones: estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone, testosterone and dehydroepiandrosterone were measured in the luteal phase. All examined women had normal mean levels of gonadal hormones. In the post MI patients leading a sedentary life style, a significantly lower mean progesterone concentration was observed (16.29 ± 9.11 versus 29.43 ± 21.14 nmol/l, p < 0.05) and significantly higher mean testosterone concentration (2.34 ± 0.98 versus 1.76 ± 1.09 nmol/l, p < 0.05) when compared to patients from the same group, but leading a more active life. In obese post MI women (BMI ≥ 30 kg/m(2)) a lower mean concentration of progesterone was detected (18.02 ± 8.12 versus 26.16 ± 14.72 nmol/l, p < 0.05), than in slimmer patients from the same group. In post MI women with a positive family history for CAD, a significantly higher mean concentration of testosterone was detected (2.31 ± 1.22 versus 1.67 ± 0.74 nmol/l, p < 0.05) than in patients with no family history. The results suggest a correlation between levels of gonadal hormones and classical CAD risk factors.     

Developmental profiles of TSH, sex steroids, and their receptors in the thyroid and their relevance to thyroid growth in immature rats.

Sex steroids are reported to influence thyroid pathogenesis in human and experimental animals. However, there is no report on this phenomenon during the early developmental period. The mitotic activity of thyrocytes in rats reaches its peak by day 10 postpartum. Thyrocytes actively proliferate in immature rats during the first three postnatal weeks, during which the pre-pubertal rise in serum titers of testosterone and estradiol has been recorded. The aim of the present study was to analyze whether there is a physiological relevance between thyroid growth and sex steroids during the postnatal period. Serum and thyroid tissue hormones (TSH, testosterone, and estradiol) were assayed by liquid phase RIA, and receptors for these hormones were also quantified. The peak rate of thyrocyte proliferation was observed during the second postnatal week in rats. Since the concentrations of sex steroids and their receptors also reached a peak around this period, it is suggested that elevated sex steroids and their receptors in the thyroid might enhance thyrocyte proliferation. A positive correlation between thyroid growth indices and sex steroids and their receptors further strengthens this suggestion. This is a preliminary study, and further experimental study may strengthen this proposal. This is the first report to show the availability of sex steroids and their receptors in the thyroid glands of immature rats under normal conditions.     

Androgens Involvement in the Pathogenesis of Renal Stones Formation

Objective

The potential role for the gonadal steroids in the pathogenesis of urolithiasis, higher mean of plasma oxalate concentration and kidney calcium oxalate deposition influenced by androgens in men has been proposed. In this study, the serum levels of steroid hormones as a pathogenesis of this condition in male patients with active renal stone disease compared with controls was investigated.

Methods

Forty patients diagnosed with renal stones and hospitalized for further clinical treatments or referred to our office after ultrasonographic evaluations participated in the study. Forty six healthy subjects served as controls. Steroid sex hormones in the plasma samples including testosterone, free testosterone, dihydrotestosterone, estradiol, and sex hormone binding globulin were analyzed.

Results

A significant difference was observed between patients and the control subjects regarding serum testosterone, free testosterone, dihydrotestosterone, estradiol, and sex hormone binding globulin.

Conclusions

Based on the results, a higher androgens level was diagnosed in renal stone patients, indicating a possibility of a substantial pathogenic role of testosterone, free testosterone, and dihydrotestosterone involvement in the pathogenesis of renal stones formation. Therefore, data presentation and further investigation on the relation between male steroids and urolithiasis is of importance and should be considered in evaluation of the etiology of the disease.     

Dynamics of reproductive hormones during downstream migration in females of the Japanese eel, Anguilla japonica

The profiles of sex steroids (estradiol-17β, testosterone and 11-ketotestosterone) and the mRNA levels of gonadotropins (luteinizing hormone and follicle-stimulating hormone) were investigated before and after downstream migration in females of the Japanese eel species Anguilla japonica, which were collected in the brackish Hamana Lake and its inlet freshwater rivers. Eels were separated into three groups using otolith microchemistry: 'migrants' that grew in the inlet rivers and then made a downstream migration to Hamana Lake mainly in October and November; 'non-migrant' yellow eels caught in rivers during the same season; and 'residents,' which were yellow eels caught in rivers in August. Sex steroid levels, especially those of testosterone and 11-ketotestosterone, were higher in migrants than in non-migrants and residents. Real-time quantitative PCR analysis indicated that mRNA levels of luteinizing hormone (LH) β-subunits were significantly higher in migrants than in other groups, whereas those of follicle-stimulating hormone β-subunits did not show significant changes during downstream migration. The high levels of these hormones during downstream migration raise the question about if they also play a role in motivating the migratory behavior of eels.     

Ovarian steroid synthesis in tissue culture after administration of hormones and epidermal growth factor

The features of steroidogenesis of immature mouse ovaries in culture under the influence of follicle-stimulating hormones (FSH), human chorionic gonadotropin (hCG), epidermal growth factor (EGF) and insulin have been investigated during the period of reinitiation of meiosis in the oocytes. Secretion of progesterone is stimulated after addition of FSH, hCG and of insulin and EGF combination to the medium. EGF increases FSH-stimulated progesterone secretion and inhibits estradiol secretion. The ratios progesterone/estradiol and testosterone/estradiol increase, when EGF is added to the culture medium. It is analogous to the action of hCG. It is suggested that EGF may be an intrafollicular EGF regulator of luteinizing hormone action on the sex and somatic cells of the mammalian ovaries.     

Testosterone and estradiol up-regulate androgen and estrogen receptors in immature and adult rat thyroid glands in vivo

Thyroid gland is one of the non-classical target organs for sex steroids. Presence of androgen and estrogen receptors in the neoplastic and non-neoplastic thyroid glands of mammalian species is well documented. The aim of the present study is to elucidate the changes in serum and thyroidal sex steroids, and their receptors in the thyroid gland of rats from immature to adult age under gonadectomized (GDX) and sex steroids replaced conditions. Normal Wistar male and female rats from immature to adult age (day 21, 30, 45, 60 and 160 post-partum (pp)) were used in the present study. One group (I) of rats was GDX at an early age (day 10 pp) and the other group (II) at the adult age (day 120 pp). Group I rats were sacrificed at different experimental periods such as 21, 30, 45 and 60 days pp, and group II rats were sacrificed at day 160 pp. Another group of GDX rats from group I and II were replaced with physiological doses of testosterone or estradiol. Serum and thyroidal concentrations of sex steroids were estimated by RIA method and the concentrations of receptors by radioreceptor assay. Gonadectomy significantly decreased serum and thyroidal testosterone and estradiol and concentrations of androgen receptor (AR) and estrogen receptor (ER) in the thyroid. Replacement of sex steroids to GDX rats restored the normal level of sex steroids, AR and ER. Therefore, it is suggested from the present study that (i). sex steroids up-regulate their own receptors in the thyroid, (ii). sex steroids may influence thyroid growth and the proliferation of thyrocytes by modulating their receptor concentrations in the thyroid.     

Prenatal testosterone exposure leads to hypertension that is gonadal hormone-dependent in adult rat male and female offspring

Prenatal testosterone exposure impacts postnatal reproductive and endocrine function, leading to alterations in sex steroid levels. Because gonadal steroids are key regulators of cardiovascular function, it is possible that alteration in sex steroid hormones may contribute to development of hypertension in prenatally testosterone-exposed adults. The objectives of this study were to evaluate whether prenatal testosterone exposure leads to development of hypertension in adult males and females and to assess the influence of gonadal hormones on arterial pressure in these animals. Offspring of pregnant rats treated with testosterone propionate or its vehicle (controls) were examined. Subsets of male and female offspring were gonadectomized at 7 wk of age, and some offspring from age 7 to 24 wk received hormone replacement, while others did not. Testosterone exposure during prenatal life significantly increased arterial pressure in both male and female adult offspring; however, the effect was greater in males. Prenatal androgen-exposed males and females had more circulating testosterone during adult life, with no change in estradiol levels. Gonadectomy prevented hyperandrogenism and also reversed hypertension in these rats. Testosterone replacement in orchiectomized males restored hypertension, while estradiol replacement in ovariectomized females was without effect. Steroidal changes were associated with defective expression of gonadal steroidogenic genes, with Star, Sf1, and Hsd17b1 upregulation in testes. In ovaries, Star and Cyp11a1 genes were upregulated, while Cyp19 was downregulated. This study showed that prenatal testosterone exposure led to development of gonad-dependent hypertension during adult life. Defective steroidogenesis may contribute in part to the observed steroidal changes.     

Novel Endocrine Disrupter Effects of Classic and Atypical Antipsychotic Agents and Divalproex: Induction of Adrenal Hyperandrogenism,Reversible with Metformin or Rosiglitazone

ObjectiveTo ascertain an association between the a priori known insulin resistance caused by antipsychotic agents and divalproex and adrenal hyperandrogenism and to determine whether the associated hyperandrogenism is reversible with insulin sensitizers.MethodsWe studied 26 consecutive psychiatric inpatients (22 women and 4 men) receiving the aforementioned medications, who were referred to us for a consultation. They ranged in age from 19 to 79 years and had a mean body mass index (SEM) of 32.35 ± 1.26 kg/m². Between 8 AM and 9 AM, blood samples were collected for 17-hydroxyprogesterone, 17-hydroxypregnenolone, androstenedione, dehydroepiandrosterone (DHEA), DHEA sulfate, 11-deoxycortisol, luteinizing hormone and follicle-stimulating hormone (in reproductive age women), estrone, estradiol (in reproductive age women), free testosterone (in women), deoxycorticosterone, and sex hormone-binding globulin (SHBG), which were measured by radioimmunoassay, after chromatography if necessary. For intact, premenopausal women, measurement of the abnormal steroid metabolite or SHBG level was repeated during prednisone therapy (5 mg at bedtime) to document the likely adrenal origin of the abnormality. Men, women who had undergone bilateral oophorectomy, and postmenopausal women had hyperandrogenism of adrenal origin by default. Clinical features included central obesity, acanthosis, hirsutism, alopecia, type 2 diabetes mellitus, and oligomenorrhea.ResultsWe found reversed estrone/estradiol ratios in 4 patients, decreased SHBG in 4, increased 17-hydroxypregnenolone in 8, increased 17-hydroxyprogesterone in 2, increased deoxycorticosterone in 2, increased DHEA sulfate in 1, increased 11-deoxycortisol in 4, increased androstenedione in 1, and reversed ratios of luteinizing hormone to follicle-stimulating hormone in 2. The biochemical abnormalities were corrected in 8 of 8 patients receiving metformin and in 2 of 2 patients receiving rosiglitazone.ConclusionInsulin resistance caused by antipsychotic agents and divalproex is associated with adrenal hyperandrogenism. Metformin and rosiglitazone correct the biochemical abnormalities detected without compromising their psychotropic effect. Adrenal androgen synthesis may be increased by hyperinsulinemia-induced hyperphosphorylation of P450c17α, resulting in an increase in its 17,20-lyase activity, which magnifies the effects of any distal steroidogenic enzyme defects. Treatment with metformin or rosiglitazone prevents excess adrenal androgen synthesis. (Endocr Pract. 2007; 13:601-608)     

Age-related changes in blood concentration of hypothalamic-pituitary-adrenal axis hormones, their central and peripheral regulators in healthy men

We studied concentrations of cortisol, its precursors and active form in human blood and relation to the changes in concentration of central and peripheral hormonal regulators (total 36 parameters) in healthy male volunteers aged 18-72 y.o. The study demonstrated a significant decrease in blood concentrations of unutilazed cortisol precursors (pregnenolone and progesterone) with advanced age accompanied by maintenance of total and free cortisol concentrations. We found age-related decrease in ACTH level that is a known hypophysial stimulant of cortisol and cortisol precursor synthesis in adrenal glands. Cortisol and ACTH levels in study population had different correlation behavior in relation to central and peripheral regulators for hormonal axes. CONCLUSION: cortisol level remains stable with advanced age in males despite the decrease in steroidogenic activity and blood ACTH level. This may be due to the imbalance in the regulation of cortisol and ACTH production by central and peripheral regulators especially by hormones of reproductive and somatotrophic axes.     

Faecal sexual steroids in sex typing and endocrine status of great bustards

Faecal sexual steroids have been used in field studies evaluating the relationships between gender and the multiple factors influencing endocrine status of individuals. The determination of faecal steroids has been also proposed as an alternative, non-invasive sexing method when other methods were deemed impractical or risky for the health of birds. In this study, we quantified sexual steroid hormones in faeces of the great bustard (Otis tarda), a large and sexually dimorphic polyginic bird species that it is threatened and subjected to intense wildlife management. We evaluated differences between captivity and wild conditions, flocks and sexes, and used faecal steroids to develop sex determination procedures. We found similar steroid levels in captive and wild bustards, no differences between unisexual wild flocks and clear between-sexes differences in testosterone but not estradiol. Faecal steroids accurately discriminated gender in both captive and wild known-sex great bustards. Total testosterone concentration was always higher than estradiol concentration in faecal samples from males, but estradiol was not always higher than testosterone in females. Faecal steroids failed to reveal the presence of young males in female flocks during winter, despite faecal testosterone levels increased with age in a small sample of captive males. Our results show that faecal steroid measurement for both sexing and characterizing the endocrine status of great bustards is feasible, and therefore it should be valuable in wildlife management, especially in combination with additional information obtained from faeces as diet.     

Expression of steroidogenic enzymes and synthesis of sex steroid hormones from DHEA in skeletal muscle of rats

The functional importance of sex steroid hormones (testosterone and estrogens), derived from extragonadal tissues, has recently gained significant appreciation. Circulating dehydroepiandrosterone (DHEA) is peripherally taken up and converted to testosterone by 3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD, and testosterone in turn is irreversibly converted to estrogens by aromatase cytochrome P-450 (P450arom). Although sex steroid hormones have been implicated in skeletal muscle regulation and adaptation, it is unclear whether skeletal muscles have a local steroidogenic enzymatic machinery capable of metabolizing circulating DHEA. Thus, here, we investigate whether the three key steroidogenic enzymes (3beta-HSD, 17beta-HSD, and P450arom) are present in the skeletal muscle and are capable of generating sex steroid hormones. Consistent with our hypothesis, the present study demonstrates mRNA and protein expression of these enzymes in the skeletal muscle cells of rats both in vivo and in culture (in vitro). Importantly, we also show an intracellular formation of testosterone and estradiol from DHEA or testosterone in cultured muscle cells in a dose-dependent manner. These findings are novel and important in that they provide the first evidence showing that skeletal muscles are capable of locally synthesizing sex steroid hormones from circulating DHEA or testosterone.     

Fertility in the male gorilla (Gorilla gorilla): Relationship to semen parameters and serum hormones

Circulating levels of steroid and protein hormones were measured in 17 adult male lowland gorillas (Gorilla gorilla). The population included both fertile and infertile males as identified by previous siring of offspring and presence or absence of spermatozoa in the ejaculate obtained by rectal probe electrostimulation. Correlations were sought between levels of testosterone, dihydrotestosterone, androstenedione, estrone, estradiol, progesterone, 170H-progesterone, dihydroepiandrosterone, luteinizing hormone, follicle-stimulating hormone (FSH), and potential fertility status. The results identify normal circulating levels of these hormones, and indicate that aspermatogenesis and infertility are not necessarily associated with any alteration in levels of gonadal steroids. There is an association of aspermatogenesis with elevation of FSH. Levels of adrenal androgens are more similar to other non-human primates than to the human, which is of interest because in other aspects of reproductive physiology so far investigated the gorilla has proved to resemble the human more closely than it does the other nonhuman primates.     

Comparison of serum steroid responses to a single injection of hCG in man and rat

The responses of peripheral serum steroids to a single injection of hCG (80 IU/kg b wt) were compared in adult male rats and humans. Before hCG, the quantitatively dominating steroids were dehydroepiandrosterone, testosterone and 17-hydroxypregnenolone in the men, and testosterone and progesterone in the rats. One hour after hCG the concentrations of testosterone and all its precursors measured except for pregnenolone were significantly elevated in the rat serum, whereas a clear rapid response was not observed in the men. Transient blockade of C21 steroid side-chain cleavage was seen in both species at about 24-36 h after hCG, which occurred at the same time as the maximum concentration of estradiol in the men. No changes in rat serum estradiol concentrations were observed. Both species showed a secondary stimulation of testosterone and androstenedione formation at around 3 days. Our findings are compatible with the concept that the main difference in the gonadotropin-stimulated steroidogenesis in man and rat is the magnitude of the rapid steroidogenic response to hCG, which is very small in man and indicates smaller supply or lesser metabolism of mitochondrial cholesterol in human testis.     

The effect of rapid and depot testosterone and estradiol on spatial performance in water maze

Men and women differ in some cognitive functions including spatial abilities. These differences seem to be affected by sex steroids, but the results are controversial. The aim of this work is to describe the effects of rapid or depot testosterone and estradiol on spatial memory in rats. Thirty-two adult male Wistar rats were divided into 6 groups. Five groups were gonadectomized, and one group was left as control. Castrated groups received sterile oil, testosterone isobutyras, testosterone propionate, estradiol dipropionate or estradiol benzoate. We evaluated spatial performance (escape latency, overall improvement, and time in the quadrant after platform removal) of the rats in a spatial water maze. Animals receiving exogenous sex steroids showed higher plasma concentrations of the particular hormones. Experimental groups improved during the acquisition spatial trials in the water maze. No significant differences between the groups during probe trial were found. In overall improvement, the testosterone depot and estradiol depot groups showed less improvement in comparison to the control groups (P<0.05). No differences in respect to administered hormones were found in corresponding receptor gene expression in hippocampus. In conclusion, exogenous testosterone affects spatial memory of adult castrated males.     

Age-related changes in the blood concentrations of the hypothalamic-pituitary-adrenal axis hormones in healthy men: Relations with other hormonal axes

The concentrations of cortisol, its precursors, and its active form in human blood, as well as its relationship to changes in the concentration of central and peripheral hormonal regulators (a total of 36 parameters), were studied in healthy male volunteers aged 18–72 years. The study demonstrated a significant decrease in the blood concentrations of unutilized cortisol precursors (pregnenolone and progesterone) with age accompanied by the maintenance of constant total and free cortisol concentrations. We found an age-related decrease in the adrenocorticotropic hormone (ACTH) level that is a well-known pituitary stimulant of cortisol and cortisol precursor synthesis in the adrenal glands. The cortisol and ACTH levels in the age interval studied exhibited different correlations with the central and peripheral regulators of the hormonal axes. The conclusion was drawn that the cortisol level remains stable with increasing age in men, despite the decrease in the steroidogenic activity and blood ACTH level. This may be due to the imbalance in the regulation of cortisol and ACTH production by the central and peripheral regulators, especially by the hormones of the reproductive and somatotrophic axes.     

Effects of transdermal application of 7-oxo-DHEA on the levels of steroid hormones, gonadotropins and lipids in healthy men

The aim of this study was to investigate the effect of 7-oxo-DHEA (dehydroepiandrosterone) on the serum levels of steroid sexual hormones, gonadotropins, lipids and lipoproteins in men. 7-oxo-DHEA was applied onto the skin as a gel to 10 volunteers aged 27 to 72 years for 5 consecutive days. The single dose contained 25 mg 7-oxo-DHEA. Serum concentrations of testosterone, estradiol, cortisol, androstenedione, luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), total cholesterol, HDL- and LDL-cholesterol, triglycerides, apolipoprotein A-I and B and lipoprotein(a) were measured before the beginning and shortly after the end of the steroid application. After the treatment, we noted the following significant changes: a decline of testosterone and estradiol levels, increase of LH, HDL-cholesterol and apolipoprotein A-I levels. The decrease of total cholesterol levels was of the borderline significance. A slight but significant increase was found in apolipoprotein B and lipoprotein(a). The most expressive was the fall of the atherogenic index. We suggest that the gel containing 7-oxo-DHEA might be a suitable drug for improving the composition of the steroid and lipid parameters in elderly men.     

Androgen control of male sex behavior in the crested newt (Triturus cristatus carnifex Laur.): Castration and sex steroid administration

Castration significantly lowers serum testosterone in sexually active male Triturus cristatus. Replacement therapy by implants of testosterone in silastic capsules elevates the serum testosterone level to higher values than normal. Sex behavior is depressed by castration and partially reinstated by replacement therapy with testosterone. 5α-dihydrotestosterone was the only testosterone metabolite showing some behavioral effectiveness in castrates; estradiol and 5β-dihydrotestosterone failed to elicit sex behavior.