Persistent Organochlorine Pollutants with Endocrine Activity and Blood Steroid Hormone Levels in Middle-Aged Men

Background

Studies relating long-term exposure to persistent organochlorine pollutants (POPs) with endocrine activities (endocrine disrupting chemicals) on circulating levels of steroid hormones have been limited to a small number of hormones and reported conflicting results.

Objective

We examined the relationship between serum concentrations of dehydroepiandrosterone, dehydroepiandrosterone sulphate, androstenedione, androstenediol, testosterone, free and bioavailable testosterone, dihydrotestosterone, estrone, estrone sulphate, estradiol, sex-hormone binding globulin, follicle-stimulating hormone, and luteinizing hormone as a function of level of exposure to three POPs known to interfere with hormone-regulated processes in different way: dichlorodiphenyl dichloroethene (DDE), polychlorinated biphenyl (PCB) congener 153, and chlordecone.

Methods

We collected fasting, morning serum samples from 277 healthy, non obese, middle-aged men from the French West Indies. Steroid hormones were determined by gas chromatography-mass spectrometry, except for dehydroepiandrosterone sulphate, which was determined by immunological assay, as were the concentrations of sex-hormone binding globulin, follicle-stimulating hormone and luteinizing hormone. Associations were assessed by multiple linear regression analysis, controlling for confounding factors, in a backward elimination procedure, in multiple bootstrap samples.

Results

DDE exposure was negatively associated to dihydrotestosterone level and positively associated to luteinizing hormone level. PCB 153 was positively associated to androstenedione and estrone levels. No association was found for chlordecone.

Conclusions

These results suggested that the endocrine response pattern, estimated by determining blood levels of steroid hormones, varies depending on the POPs studied, possibly reflecting differences in the modes of action generally attributed to these compounds. It remains to be investigated whether this response pattern is predictive of the subsequent occurrence of disease.     

Esterification of dehydroepiandrosterone by human plasma HDL

Evidence for metabolic esterification of dehydroepiandrosterone (DHEA) in human blood plasma, identification of the active lipoprotein (LP) subclass involved, namely HDL3, as well as positive identification of the long-chain fatty acid esters of DHEA formed as incubation products is presented. The esterification reaction of DHEA and subsequent transfer and transport of DHEA esters in human plasma appears to proceed in a manner similar to that of cholesterol. The experiments presented serve as a model predicting similar metabolic transformations during HDL3 interactions with other steroid hormones that have the delta 5-3 beta-hydroxy steroid ring structure and exhibit nonequilibrium associations with HDL. These observations imply that significant quantities of DHEA, particularly in the conjugated ester form, can enter cells via the membrane receptor-mediated pathways of LP internalization.     

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.     

Plasma testosterone transport in primates

All primate species, including Old and New World primates and prosimians have a plasma testosterone-estradiol binding globulin (TeBG), which is a glycoprotein and has a similar mobility in polyacrylamide gel electrophoresis. In New World primates the TeBG binding capacity for [3H]testosterone was higher and its affinity lower than in Old World primates. These changes were associated with high unbound plasma testosterone concentrations in these species. Binding parameters of TeBG in prosimian species varied markedly. Thus, in primate evolution TeBG was conserved despite marked differences in binding characteristics. In New World primates changes are associated with high total and unbound testosterone, a finding concordant with alterations of other steroid hormones concentration in these species with "generalized steroid hormone resistance".     

Effect of hyperalphalipoproteinemia on structural characteristics of plasma lipoproteins according to electron paramagnetic resonance spin probe findings

Spin probe, a stearic acid derivative, was used to study the structural features of different lipoproteins (LP) from plasma of subjects with different plasma level of high density LP (HDLP). Access of spin probe located in the internal nonpolar regions of HDLP for the reducer, ascorbic acid, was higher in hyperalphalipoproteinemia than in mean values of HDLP cholesterol concentration. An analogous effect was seen in subjects with LP of very low density. Possible causes of such differences as well as their role in biochemical reactions that proceed with LP participation are discussed.     

Studies on lipoprotein and adrenal steroidogenesis: II. Utilization of low density lipoprotein- and high density lipoprotein-cholesterol for steroid production in functioning human adrenocortical adenoma cells in culture

We examined the utilization of human low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol for steroid production in primary monolayer culture cells from adenomas of primary aldosteronism and Cushing's syndrome and an adrenal of nodular hyperplasia of Cushing's syndrome. We compared the data obtained with findings in the case of cultured normal human adrenocortical cells. In the presence of 10(-7) M adrenocorticotropin (ACTH), the addition of either LDL or HDL to the culture medium at a cholesterol concentration of 100 micrograms/ml led to a significant increase in the daily secretion rates of cortisol, dehydroepiandrosterone sulfate (DHEA-S) and aldosterone in the adenoma and nodular hyperplasia cells, as in the normal cells. Although LDL greatly increased the secretion of steroid hormones, no significant difference in steroid secretion following the treatments with LDL and HDL were observed in these cultured cells. The contribution of endogenous cholesterol to steroid production was also high, thereby indicating that the neoplastic transformation did not have untoward effects. Cells from adenomas of primary aldosteronism secreted not only aldosterone, but also cortisol and DHEA-S. The daily secretion rates of these steroids were markedly increased when ACTH was added to the medium. With prolonged exposure to ACTH, however, the rate of aldosterone secretion showed a gradual decrease with the incubation time. This decrease might be due to the impaired conversion of corticosterone to 18-hydroxycorticosterone. In case of adenomas in patients with Cushing's syndrome, the secretion of steroid hormones varied in quantity and quality, depending on the type of plasma cortisol response to the rapid ACTH test in vivo, thereby suggesting that the adrenocortical adenoma of Cushing's syndrome might be divided into two subtypes. These results indicate that human functioning adrenocortical adenoma cells utilize plasma lipoproteins as a source of cholesterol for steroidogenesis during the prolonged stimulation of steroid secretion.     

The analysis of interaction of lipoproteins and steroid hormones

Using the methods of gel-filtration and fluorescence quenching, it has been demonstrated that plasma lipoproteins bind steroid hormones and can therefore play a role in their active transport in the body. High density lipoproteins demonstrate the highest affinity for steroids.     

Metabolic conversion of six steroid hormones by human plasma high-density lipoprotein

Sixteen different steroid hormones were individually tested in equilibrium dialysis against plasma high-density, low-density and very-low-density lipoproteins (HDL, LDL, VLDL) under physiological conditions. Six steroid hormones (androstenediol (AEDOL), estradiol (E2), dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), pregnenolone (P5), and progesterone (P4)) demonstrated metabolic interaction with HDL, particularly HDL3. In four cases (AEDOL-HDL, E2-HDL, DHEA-HDL and P5-HDL) the interaction products were more lipophilic, while in the other two cases (DHT-HDL, P4-HDL) they were hydrophilic compared to the original steroid hormone substrates. The lipophilic products appeared to be long-chain fatty acid steroid hormone esters at the C-3 position of the steroid hormone. This was confirmed, in preparative incubations, for the two strongest steroid hormone reactants (DHEA and P5) by gas chromatography-mass spectroscopy (GC-MS). Naturally occurring DHEA and P5 esters were identified in normal fresh human plasma by GC-MS, and their fatty acid compositions were similar to that of native HDL3 cholesterol esters. It was deduced that lecithin-cholesterol acyl transferase enzyme was responsible for the lipophilic type conversion activity with P5 greater than DHEA greater than AEDOL greater than E2. For DHT and P4, which exhibit a fundamentally different (hydrophilic) type of metabolic conversion, a totally different form of HDL-associated metabolic activity is indicated. These newly discovered steroid hormone-lipoprotein interactions may be important for steroid hormone processing in plasma and/or steroid hormone delivery to cells.     

Sex steroids and steroid binding proteins in primary biliary cirrhosis

In a longitudinal study on sex steroids and steroid binding proteins in primary biliary cirrhosis (PBC), 9 female patients were compared with 27 strictly age-matched healthy controls. In the patients we found elevated levels of androstenedione and, in advanced disease, of testosterone. Levels of total oestrone, dehydroepiandrosterone and dehydroepiandrosterone sulphate (DHAS) were not significantly different from controls, although numerically lower values were noted for the two later steroids in the PBC patients. The mean albumin level in the PBC patients was at the lower reference limit. A significant positive correlation between DHAS and albumin was found in the patients. The levels of sex hormone binding globulin (SHBG) were elevated in the patients and increased further with progressive disease as measured by N-demethylating capacity. The results suggest a close association, unrelated to sex hormone levels, between increased SHBG synthesis and progressive hepatocellular failure in PBC.     

Circadian rhythms of androgen levels in the blood of male hamadryas baboons

Radioimmunoassay was used to investigate circadian rhythms of blood plasma testosterone, 5 alpha-dihydrotestosterone, androstendione and dehydroepiandrosterone in intact animals and in those preadapted for experimental conditions. Blood plasma of monkey demonstrated monophasic circadian rhythms in the levels of androstendione, dehydroepiandrosterone and 5 alpha-dihydrotestosterone, with the maximal values seen early in the morning and minimal values in the evening. Circadian rhythms of testosterone were opposite in character. The adaptation of monkeys for housing and experimental conditions was marked by an increase in testosterone and 5 alpha-dihydrotestosterone levels in the blood as well as by an insignificant elevation of the levels of androgens of adrenal origin, leading to the changes in circadian rhythms of steroid hormones.     

Administration of pregnenolone and dehydroepiandrosterone to guinea pigs and rats causes the accumulation of fatty acid esters of pregnenolone and dehydroepiandrosterone in plasma lipoproteins.

Steroids were administered continuously to guinea pigs and rats using subcutaneously applied silastic tubing implants, and the effects on circulating steroid and steroid conjugate levels were monitored. Using implants filled with pregnenolone, we observed that pregnenolone had a marked effect on increasing the levels of its fatty acid-esterified derivative, while dehydroepiandrosterone-releasing implants produced a rise in circulating nonconjugated dehydroepiandrosterone, androst-5-ene-3 beta,17 beta-diol, androstenedione, testosterone, and lipoidal derivatives of both dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol. Implants filled with androstenedione produced a 20-fold increase in plasma androstenedione levels relative to untreated controls and a corresponding five-fold increase over control testosterone levels. No fatty acid-esterified derivative of testosterone could be detected within the plasma. Lipoproteins were isolated from both rats and guinea pigs treated with implants filled with pregnenolone or dehydroepiandrosterone. The steroid and steroid fatty acid esters present in each fraction were analyzed, revealing that approximately 75% of all the fatty acid esters of pregnenolone recovered in the lipoproteins was localized within the high-density lipoprotein (HDL) fraction of both guinea pig and rat plasma. Similarly, lipoidal dehydroepiandrosterone was found associated predominantly with the low-density lipoprotein and HDL fractions in the guinea pig, while in the rat this steroid conjugate was exclusively within the HDL fraction. High-density lipoprotein-incorporated tritiated pregnenolone fatty acid esters and dehydroepiandrosterone fatty acid esters were injected into castrated male guinea pigs to study the fate of these complexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of adenylate cyclase in a mammary carcinoma cell line by human corticosteroid-binding globulin

Corticosteroid-Binding globulin (CBG) is a plasma protein that binds certain steroid hormones, mainly cortisol and progesterone. It has been demonstrated recently that specific binding sites for this protein exist on cell membranes. In this communication we establish that binding to these sites results in the induction of adenylate cyclase activity and the accumulation of cAMP in MCF-7 cells. These events are critically dependent upon a steroid being bound to CBG. These data are consistent with the hypothesis that CBG is a prohormone which is activated when cortisol is bound to it.     

Thermotropic structural rearrangements in blood plasma lipoproteins in ischemic heart disease

Structural properties of blood plasma lipoproteins (LP) from coronary heart disease (CHD) patients were examined. Substantial differences were found in the pattern of the heat-induced structural restitution of LP of all classes in health and disease. At the same time no such differences were discovered in lipids isolated from LP. In high density lipoproteins from the plasma of CHD patients, a decrease in the microenvironmental polarity was shown to take place at a depth of 8 A from the surface of LP. The data obtained indicate substantial changes in the structural organization of LP of all classes in CHD. It is assumed that these changes are consequent on the modification of apoproteins and/or protein-lipid interactions in LP.     

Studies on nuclear binding of dehydroepiandrosterone in hepatocytes.

Experiments were conducted to determine if dehydroepiandrosterone (DHEA) specifically binds to liver nuclei or interferes in the binding of other steroid hormones. Hepatocytes were isolated from obese, female Zucker rats that were treated with and without 0.6% DHEA in their diets for 2 weeks. The hepatocytes were incubated with either [3H]DHEA, [3H]estrone, or [3H]corticosterone. The nuclei isolated from the incubated cells from either control or DHEA-treated rats had no binding with [3H]DHEA, but had the expected binding with [3H]estrone and [3H]corticosterone. Furthermore, increasing concentrations of cold, unlabeled DHEA in the incubation media with [3H]estrone or [3H]corticosterone failed to have any effect on the binding of either of these steroid hormones to the nuclei. These results suggest that DHEA treatment does not exert its effects on cellular metabolism through a receptor-mediated mechanism like other steroid hormones or by interfering in the expression of steroid hormones such as estrone and corticosterone.     

Quantitative characteristics of interactions of blood lipoproteins and steroid hormones]

Human and serum lipoproteins interaction with steroid hormones (corticosterone and hydrocortisone) were studied. Methods of fluorescence quenching titration and equilibrium dialysis were used for quantitative evaluation of VLDL, LDL and HDL glucocorticoids binding ability. Association constants were found to be 0.6-2.0 x 10 M for corticosterone and 4.0-8.0 x 10 M for hydrocortisone. The number of binding sites ranged from 3 to 300 for different classes of lipoproteins. Our data suggest high specificity of serum lipoproteins binding with corticosterone and hydrocortisone.     

Chronic cigarette smoking alters circulating sex hormones and neuroactive steroids in premenopausal women

Chronic smoking alters the circulating levels of sex hormones and possibly also the neuroactive steroids. However, the data available is limited. Therefore, a broad spectrum of free and conjugated steroids and related substances was quantified by GC-MS and RIA in premenopausal smokers and in age-matched (38.9+/-7.3 years of age) non-smokers in the follicular (FP) and luteal phases (LP) of menstrual cycle (10 non-smokers and 10 smokers, in the FP, and 10 non-smokers and 8 smokers in the LP). Smokers in both phases of the menstrual cycle showed higher levels of conjugated 17-hydroxypregnenolone, 5alpha-dihydroprogesterone, conjugated isopregnanolone, conjugated 5alpha-pregnane-3beta,20alpha-diol, conjugated androstenediol, androstenedione, testosterone, free testosterone, conjugated 5alpha-androstane-3alpha/beta,17beta-diols, and higher free testosterone index. In the FP, the smokers exhibited higher levels of conjugated pregnenolone, progesterone, conjugated pregnanolone, lutropin, and a higher lutropin/follitropin ratio, but lower levels of cortisol, allopregnanolone, and pregnanolone. In the LP, the smokers exhibited higher levels of free and conjugated 20alpha-dihydropregnenolone, free and conjugated dehydroepiandrosterone, free androstenediol, 5alpha-dihydrotestosterone, free and conjugated androsterone, free and conjugated epiandrosterone, free and conjugated etiocholanolone, 7alpha/beta-hydroxy-dehydroepiandrosterone isomers, and follitropin but lower levels of estradiol and sex hormone binding globulin (SHBG) and lower values of the lutropin/follitropin ratio. In conclusion, chronic cigarette smoking augments serum androgens and their 5alpha/beta-reduced metabolites (including GABAergic substances) but suppresses the levels of estradiol in the LP and SHBG and may induce hyperandrogenism in female smokers. The female smokers had pronouncedly increased serum progestogens but paradoxically suppressed levels of their GABA-ergic metabolites. Further investigation is needed concerning these effects.     

The pathophysiological implications of circulating androgens on bone mineral density in a normal female population

In this cross-sectional study performed on 147 healthy or osteoporotic, but otherwise normal premenopausal (n = 26 and n = 13, respectively) or postmenopausal (n = 40 and n = 68, respectively) women aged 40.1+/-9.9 and 61.9+/-8.9 years, respectively (range 20-82 years), serum ovarian and adrenal sex steroids and their relationship to bone mineral density (BMD) were evaluated. The levels of dehydroepiandrosterone sulfate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (AD), and estradiol correlated positively with BMD at the hip and spine as did serum testosterone with BMD at the spine. An inverse relationship was found between sex hormone binding globulin (SHBG) levels and BMD at the spine and hip. After adjustment for age, body mass, and sex steroid confounders, the bioavailable testosterone value (but not the DHEAS, DHEA, AD, or SHBG) values was demonstrated to be an independent determinant of BMD at the spine (beta 0.18, P<0.02) and hip (beta 0.24, P<0.02). Similarly, estradiol was found to be an independent determinant of BMD at the spine (beta 0.25, P<0.007). However, only SHBG levels (but not other steroid parameters) correlated positively with indices of bone remodeling, namely, serum osteocalcin and cross-linked telopeptide of type I collagen (ICTP). The present study suggests that a major decline in index of free testosterone (testosterone/SHBG) may influence the development of female osteoporosis. The clinical significance of circulating SHBG levels in the assessement of bone metabolic turnover remains to be established.     

Changes in lipoprotein binding and uptake by hepatocytes during rat liver regeneration

The binding and uptake of cholesterol enriched lipoproteins by isolated hepatocytes was decreased at 16 hours after partial hepatectomy, with a tendency to return to control values as the regeneration proceeds. The number of lipoprotein binding sites of total cellular membranes remained similar to control at 16 and 24 hours. The plasma lipoprotein pattern, determined by electrophoretic analysis, showed a lower per cent of very low density lipoproteins (VLDL) and a higher per cent of low density lipoproteins (LDL) at 16 and 24 hours post-partial hepatectomy. At these times, plasma lecithin: cholesterol acyltransferase (LCAT) activity was decreased. It is intriguing to suggest that the regenerating liver could regulated the blood lipoprotein pattern and the uptake of lipoproteins by modulating the surface expression of the receptors.     

Interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (Zonotrichia albicollis)

Plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. Mammals have both sex steroid binding globulin (SSBG) and corticosteroid binding globulin (CBG). Birds, however, have no detectable SSBG, leading to the early conclusion that birds have no plasma regulation of sex steroids. CBG, however, can bind androgens with relatively high affinity. In birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology because glucocorticoids compete with androgens for CBG binding sites. We report levels of total testosterone (T), total corticosterone, CBG, and estimated free T in the males, the more aggressive morph had higher levels of total T; female morphs did not differ. Approximately 96% of T was bound to CBG, but a lack of morph or sex-specific differences in corticosterone titers or CBG capacity caused patterns of free T to mirror those of total T. While CBG has the potential to greatly influence T availability to tissues, in this species interactions between T, CBG and corticosterone do not appear to alter general patterns of T availability to tissues.