Effects of chromium picolinate supplementation on insulin sensitivity, serum lipids, and body composition in healthy, nonobese, older men and women.

BACKGROUND: Chromium is an essential nutrient required for carbohydrate and lipid metabolism. Chromium supplementation in humans has been reported to improve glucose metabolism and improve serum lipid parameters and to reduce body fat; parameters that worsen with aging. As a result, chromium picolinate has been widely promoted as a health aid for the general population. The purpose of the study was to examine the effects of chromium supplementation on insulin sensitivity, serum lipids, and body composition in nonobese, healthy men and women of advanced age. METHODS: A randomized, double-blind, placebo-controlled study with 19 subjects (9 men and 10 women), aged 63-77, were given either chromium picolinate, 1,000 microg/d, or a placebo for 8 weeks. Serum lipids were measured at baseline and 8 weeks. Insulin sensitivity and body composition were measured with the minimal-model intravenous glucose tolerance test and dual-energy x-ray absorptiometry scan, respectively, at baseline and after 8 weeks of chromium or placebo supplementation. RESULTS: No significant change in serum lipids, insulin sensitivity, or body composition was observed in the chromium group compared with the placebo group. CONCLUSIONS: Chromium picolinate supplementation alone does not appear to improve insulin sensitivity, serum lipids, or change body composition in nonobese, healthy men and women of advanced age.

The insulin-like growth factor system in the GT1-7 GnRH neuronal cell line.

Evidence suggests that insulin-like growth factors (IGFs; IGF-I and IGF-II) are involved in the regulation of reproductive function including the development of the gonadotropin-releasing hormone (GnRH) neuronal system and the modulation of GnRH secretory activities. To further characterize the regulatory role of the IGF system on GnRH neuronal function, we have examined the gene expression of IGF-I, IGF-II, IGF-I receptor (IGF-IR), and IGF-binding proteins (IGFBPs) in a GnRH neuronal cell line (GT1-7 cells). The relative effects of IGFs and insulin on GnRH secretion by these cells was also investigated. RT-PCR analysis demonstrated IGF-I, IGF-II and IGF-IR mRNAs in GT1-7 cells. The mRNAs for IGFBP-2, -3, -4, -5 and -6 but not IGFBP-1 were also detected. Immunoreactive protein bands for IGFBP-2, -4 and -5 but not for other IGFBPs were demonstrated by Western blot with IGFBP-5 appearing to be the most abundant IGFBP secreted by GT1-7 cells. IGFBP-5 production by GT1-7 cells was stimulated by both IGF-I and IGF-II in a dose-dependent manner with approximately equal potency, whereas insulin caused no significant effect. GnRH secretion by GT1-7 cells treated with IGF-I or IGF-II but not insulin showed an increase (80-100%) at 2 h of treatment followed by a decrease (46%) at 6 h that continued up to 24 h. We conclude that the expression of IGFs, IGF-IR and IGFBPs and their interactions in the regulation of GnRH secretion by GT1-7 cells as demonstrated by our study provide a basis for an autocrine regulatory role for the IGF system in GnRH neuronal secretory activities.

Neurosteroidogenesis in astrocytes, oligodendrocytes, and neurons of cerebral cortex of rat brain.

The brain is a steroidogenic organ that expresses steroidogenic enzymes and produces neurosteroids. Although considerable information is now available regarding the steroidogenic capacity of the brain, little is known regarding the steroidogenic pathway and relative contributions of astrocytes, oligodendrocytes, and neurons to neurosteroidogenesis. In the present study, we investigated differential gene expression of the key steroidogenic enzymes using RT-PCR and quantitatively evaluated the production of neurosteroids by highly purified astrocytes, oligodendrocytes, and neurons from the cerebral cortex of neonatal rat brains using specific and sensitive RIAs. Astrocytes appear to be the most active steroidogenic cells in the brain. These cells express cytochrome P450 side-chain cleavage (P450scc), 17alpha-hydroxylase/C17-20-lyase (P450c17), 3beta-hydroxysteroid dehydrogenase (3betaHSD), 17beta-hydroxysteroid dehydrogenase (17betaHSD), and cytochrome P450 aromatase (P450arom) and produce pregnenolone (P5), progesterone (P4), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T), estradiol, and estrone. Oligodendrocytes express only P450scc and 3betaHSD and produce P5, P4, and A4. These cells do not express P450c17, 17betaHSD, or P450arom or produce DHEA, T, or estrogen. Neurons express P450scc, P450c17, 3betaHSD, and P450arom and produce P5, DHEA, A4, and estrogen, but do not express 17betaHSD or produce T. By comparing the ability of each cell type in the production of neurosteroids, astrocytes are the major producer of P4, DHEA, and androgens, whereas oligodendrocytes are predominantly the producer of P5 and neurons of estrogens. These findings serve to define the neurosteroidogenic pathway, with special emphasis on the dominant role of astrocytes and their interaction with oligodendrocytes and neurons in the genesis of DHEA and active sex steroids. Thus, we propose that neurosteroidogenesis is accomplished by a tripartite contribution of the three cell types in the brain.

Dehydroepiandrosterone: biosynthesis and metabolism in the brain.

Dehydroepiandrosterone (DHEA) is abundantly found in brain tissues of several species, including human. However, the cellular origin and pathway by which DHEA is synthesized in brain are not yet known. We have, therefore, initiated pilot experiments to explore gene expression of cytochrome P450 17alpha-hydroxylase (P450c17), the key steroidogenic enzyme for androgen synthesis, and evaluate DHEA production by highly purified astrocytes, oligodendrocytes, and neurons. Using RT-PCR, we have demonstrated for the first time that astrocytes and neurons in the cerebral cortex of neonatal rat brain express P450c17. The presence of P450c17 in astrocytes and neurons was supported by the ability of these cells to metabolize pregnenolone to DHEA in a dose-dependent manner as determined by RIA. These data were further confirmed by production of androstenedione by astrocytes using progesterone as a substrate. However, cortical neurons express a low transcript of P450c17 messenger RNA and produce low levels of DHEA and androstenedione compared with astrocytes. Oligodendrocytes neither express the messenger RNA nor produce DHEA. The production of DHEA by astrocytes is not limited to cerebral cortex, as hypothalamic astrocytes produce DHEA at a level 3 times higher than that produced by cortical astrocytes. Cortical and hypothalamic astrocytes also have the capacity to metabolize DHEA to testosterone and estradiol in a dose-dependent manner. However, hypothalamic astrocytes were 3 times more active than cortical astrocytes in the metabolism of DHEA to estradiol. In conclusion, our data presented evidence that astrocytes and neurons express P450c17 and synthesize DHEA from pregnenolone. Astrocytes also have the capacity to metabolize DHEA into sex steroid hormones. These data suggest that as in gonads and adrenal, DHEA is biosynthesized in the brain by a P450c17-dependent mechanism.

Racial differences in renal kallikrein excretion: effect of the ovulatory cycle.

BACKGROUND: Renal kallikrein excretion is diminished in essential hypertension, especially in African-Americans, and evidence exists for a major gene effect on the kallikrein phenotype. In addition, urinary kallikrein excretion differs by gender, with ovulating females having greater kallikrein excretion than males or postmenopausal females. Recent studies have shown that renal kallikrein excretion varies in females during the ovulatory cycle, with levels rising during the luteal phase and returning during the follicular phase to levels that are similar to those of males. In family studies, gender differences in urinary kallikrein excretion were present in white subjects, but not black subjects. We therefore hypothesized dysregulation of kallikrein biosynthetic responses in African-Americans. METHODS: We determined urinary kallikrein activity [chromogenic substrate S2266 (D-val-leu-arg-paranitroanilide) assay; in microU/mg creatinine] in white (N = 15) and black (N = 11) ovulating females during the ovulatory cycle. Serum progesterone, estrogen, plasma renin activity as well as urinary aldosterone, and urinary electrolytes were determined to investigate changes between mid-follicular and mid-luteal phases in the two groups. RESULTS: White and black groups were matched for age, body mass index, blood pressure, heart rate and renal function. Ovulatory cycle phases were confirmed by serum progesterone determinations, which increased significantly in whites and blacks to a comparable degree [0.84 +/- 0.14 nmol/liter (mid-follicular) to 29.77 +/- 4.70 nmol/liter (mid-luteal) in whites, 0.67 +/- 0.08 nmol/liter (mid-follicular) to 28.62 +/- 5.83 nmol/liter (mid-luteal) in blacks; P < 0.001 for cycle effect, P = NS for race effect and race X cycle interaction]. Urinary kallikrein activity increased from 623 +/- 86 microU/mg creatinine (mid-follicular) to 948 +/- 142 microU/mg creatinine (mid-luteal) in whites, but did not change in blacks during the ovulatory cycle [239 +/- 73 microU/mg creatinine (mid-follicular] to 244 +/- 41 microU/mg creatinine (mid-luteal)]. Two-way ANOVA revealed significant effects on urinary kallikrein for race (P < 0.001), cycle (P < 0.05), and race X cycle interaction (P < 0.05). Thus, white females had higher urinary kallikrein than black females, and demonstrated a significant increase in urinary kallikrein excretion during the ovulatory cycle, whereas no significant change in urinary kallikrein activity was seen in the black group. Enzyme kinetic studies and mixing studies demonstrated that these racial differences in renal kallikrein excretion were quantitative, rather than due to qualitative differences in the renal kallikrein enzyme or due to the presence of a kallikrein inhibitor. CONCLUSIONS: These results suggest pronounced blunting of menstrual cycle changes in urinary kallikrein excretion in black females. Blunted urinary kallikrein responses during the ovulatory cycle are consistent with dysregulation of renal kallikrein biosynthetic responses in African-Americans, a group at increased risk for hypertension.

Lack of insulin resistance in fibroblasts from subjects with polycystic ovary syndrome.

Insulin resistance in polycystic ovary syndrome (PCOS) is characterized by a novel defect in insulin signal transduction expressed in isolated human adipocytes as impaired insulin sensitivity for glucose transport and antilipolysis. To determine whether this is a generalized defect of a potentially genetic basis, or possibly a tissue-specific one, fibroblast cultures were established from age- and weight-matched obese normal cycling (NC; n = 5) and PCOS (n = 6) subjects. Adipocytes from the current PCOS subjects displayed impaired sensitivity for glucose transport stimulation (half-maximal effective concentration [EC50], 317 +/- 58 pmol/L in PCOS v 130 +/- 40 in NC; P < .025). Specific insulin binding was similar in fibroblasts from NC (0.57% +/- 0.10%/10(6) cells) and PCOS (0.45% +/- 0.10%) subjects. Fibroblasts from NC (4.9- +/- 0.5-fold stimulation) and PCOS (4.6- +/- 0.3-fold) subjects were equally responsive to insulin for stimulation of glucose incorporation into glycogen. Insulin sensitivity for glycogen synthesis in fibroblasts did not differ between NC (EC50, 9.6 +/- 0.9 nmol/L) and PCOS (9.1 +/- 0.9) cells. For thymidine incorporation into DNA, relative insulin responsiveness was similar in NC (2.3- +/- 0.3-fold stimulation) and PCOS (2.1- +/- 0.1-fold) fibroblasts. Insulin sensitivity for DNA synthesis was similar in NC (EC50, 12.9 +/- 2.4 nmol/L) and PCOS (7.6 +/- 1.3) cells. In summary, (1) insulin receptor binding is normal in PCOS fibroblasts; and (2) PCOS fibroblasts have normal insulin sensitivity and responsiveness for metabolic and mitogenic responses. Impaired insulin signal transduction, while present in adipocytes from a group of PCOS subjects, is not found in fibroblasts from the same subjects. This defect is not generalized to all cell types, but may be limited to specific tissues and responses.

Preliminary report on the treatment of endometriosis with low-dose mifepristone (RU 486).

OBJECTIVE: We have previously shown that treatment with mifepristone, 50 to 100 mg daily, results in amenorrhea, anovulation, and symptomatic improvement in women with endometriosis. In this study we lowered the dose to 5 mg daily to determine whether clinical efficacy is altered without other adverse actions. STUDY DESIGN: After a baseline cycle, seven women with endometriosis were given mifepristone, 5 mg daily, for 6 months. Daily symptom inventories were recorded. Laparoscopy was performed during the sixth month of therapy. RESULTS: Pelvic pain improved in six of seven patients. Cyclic bleeding ceased in all patients, but four of the seven patients complained of irregular bleeding. Surgical staging at the conclusion of the study (five of seven patients) did not detect a change in endometriosis. CONCLUSIONS: Mifepristone, 5 mg daily, resulted in symptomatic improvement, but did not stabilize the endometrium. From our experience with three doses of mifepristone, we would recommend a dose of 50 mg be used for continued investigations.

PIP: The authors' previous research has demonstrated that treatment with 50-100 mg/day of mifepristone produces symptomatic improvement of endometriosis. The present study assessed the efficacy of a substantially reduced antiprogesterone dose. After a baseline cycle, 7 US women with pelvic pain caused by endometriosis were administered 5 mg of mifepristone daily for 6 months. Clinical responsiveness was evaluated in daily symptom inventories completed by study participants. Pelvic pain improved significantly within 1 month of treatment initiation in 6 of 7 patients. Cyclic bleeding ceased in all 7 patients, but 4 women complained of irregular bleeding that begin 3-5 months into treatment. Menstrual cyclicity returned 23-37 days after study completion. 2 women did not complete the study--1 because of continued pelvic pain and 1 because of heavy bleeding during the fifth cycle. Surgical staging through laparoscopy in the 5 remaining women failed to document a significant change in endometriosis. 1 woman had a slight increase in endometriosis score compared to baseline, 1 had no change, and the remaining 3 women showed decreases from 32-45%. Given the failure of the 5 mg dose to stabilize the endometrium and the high rate of uterine bleeding, a dose of 50 mg of mifepristone is recommended for future investigations.

Corticotropin-releasing factor inhibits luteinizing hormone-stimulated P450c17 gene expression and androgen production by isolated thecal cells of human ovarian follicles.

Recently, we reported that the thecal compartment of the human ovary contains a CRF system replete with gene expression and protein for corticotropin-releasing factor (CRF), CRF-Receptor 1 (CRF-R1), and the blood-derived high affinity CRF binding protein (CRF-BP). Granulosa cells are devoid of the CRF system. The parallel increases in intensity of CRF, CRF-R1, and 17 alpha-hydroxylase messenger ribonucleic acid (mRNA) and proteins in thecal cells with follicular maturation suggest that the intraovarian CRF system may play an autocrine role regulating androgen biosynthesis, with a downstream effect on estrogen production by granulosa cells. The functionality of the ovarian CRF system may be conditioned by the relative presence of plasma-derived CRF-BP by virtue of its localization of protein, but not transcript in thecal cells and its ability to compete with CRF for the CRF receptor. To further these findings, in the present study we have examined the effect of CRF on LH-stimulated 17 alpha-hydroxylase (P450c17) gene expression and androgen production by isolated thecal cells from human ovarian follicles (11-13 mm). During the 48-h culture, addition of LH (10 ng/mL) to the medium increased by 5- and 6-fold dehydroepiandrosterone and androstenedione production by thecal cells. Remarkably, the LH-stimulated, but not basal, androgen production was inhibited by CRF in a time- and dose-dependent manner. The half-maximal (ID50) effect dose of CRF occurred at 5 x 10(-8) mol/L, and at a maximal concentration of 10(-6) mol/L, CRF completely inhibited LH-stimulated androgen production. This inhibitory effect of CRF became evident at 12 h (45%), and by 24 h the effect was more pronounced, with a 70% reduction from baseline. As determined by Northern analyses, CRF dose dependently decreased LH-stimulated P450c17 mRNA levels, with a maximal inhibition of 85% P450c17 gene expression at a CRF concentration of 10(-6) mol/L. With the addition of 10(-6) mol/L of the antagonist alpha-helical CRF-(9-41), the inhibitory effect of CRF was partially reversed for both P450c17 mRNA (75%) and androgen production (50%), indicating the CRF-R1-mediated event. In conclusion, the present study demonstrated a potent inhibitory effect of CRF on LH-stimulated dehydroepiandrosterone and androstenedione production that appears to be mediated through the reduction of P450c17 gene expression. Thus, the ovarian CRF system may function as autocrine regulators for androgen biosynthesis in the thecal cell compartment to maintain optimal substrate for estrogen biosynthesis by granulosa cells. Further studies to define the role of CRF-BP in the endocrine modulation of the intraovarian CRF system are needed.

Nutritional and endocrine-metabolic aberrations in women with functional hypothalamic amenorrhea.

The development of functional hypothalamic amenorrhea (FHA) in weight-stable, nonathletic women has long been thought to be psychogenic in origin. This study was designed to gain insight into the possibility that nutritional deficits and compensatory endocrine-metabolic adaptations contribute to the development and maintenance of FHA of the psychogenic type. Nutritional intake, insulin sensitivity, and 24-h dynamics of insulin/glucose, cortisol, leptin, somatotropic, and LH axes were simultaneously assessed in eight women with FHA not associated with exercise or weight loss and in eight age- and body mass index-matched regular cycling controls (NC). The percent fat body mass was lower and lean body mass was higher in FHA than in NC (P < 0.05). The FHA subjects scored higher (P < 0.05) on two Eating Disorder Inventory subscales and had a higher (P < 0.05) Beck depression rating than NC, although all were in the subclinical range. Although daily caloric intake did not differ, FHA consumed 50% less (P < 0.001) fat, twice (P < 0.05) as much fiber, and more carbohydrate (P < 0.05) compared to NC. During the feeding phase of the day, FHA exhibited lower glucose (P < 0.05) and insulin (P < 0.01) levels than NC, and the degree of hypoinsulinemia was directly related to relative dietary fat (r = 0.73). Although 24-h mean GH levels did not differ, the pattern of GH release in FHA was distinctly altered from that in NC. GH pulse amplitude was blunted, pulse frequency was accelerated 40% (P < 0.01), and interpulse GH concentrations were elevated 2-fold (P < 0.01) throughout the day for FHA compared to NC. This distorted pattern of GH pulses was associated with a 40% decrease (P < 0.01) in GH-binding protein levels. Levels of the insulin-dependent insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) were elevated (P < 0.001) during the feeding portion of the day in FHA and were inversely related to insulin (r = -0.50) and directly related to cortisol (r = 0.64) levels for FHA and NC groups together. Although levels of IGF-I and IGFBP-3 did not differ, the elevation of IGFBP-1 levels in FHA resulted in a reduced (P < 0.01) ratio of IGF-I/IGFBP-1, which may decrease the bioactivity and hypoglycemic effect of IGF-I. Twenty-four-hour mean leptin levels and the diurnal excursion of leptin in FHA did not differ from those in NC. LH pulse frequency was slowed 50% (P < 0.001) in FHA, with unaltered pulse amplitude, resulting in 45% lower (P < 0.01) 24-h mean LH levels for FHA compared to NC. LH pulse frequency for the two groups was related positively to insulin (r = 0.80) levels and the ratio of IGF-I/IGFBP-1 (r = 0.70) and negatively with cortisol (r = -0.61) and IGFBP-1 (r = -0.72) concentrations. In summary, we found evidence of subclinical eating disorders in weight-stable, nonathletic women with FHA accompanied by a severe restriction of dietary fat intake. Unbalanced nutrient intake in psychogenic FHA was associated with multiple endocrine-metabolic alterations. Among these, reduced levels of plasma glucose and serum GHBP, a decrease in the ratio of IGF-I/IGFBP-1, accelerated GH pulse frequency, and elevated interpulse GH levels are indicative of a hypometabolic state. In addition, the magnitude of glucoregulatory responses (increased cortisol secretion and decreased insulin/IGF-I action) were directly related to the degree of suppression of GnRH/LH pulse frequency. These results are remarkably similar to those seen in highly trained athletes with FHA(1). Thus, nutritional deficits may represent a common contributing factor to the development and maintenance of multiple neuroendocrine-metabolic aberrations underlying both psychogenic and exercise-related FHA.

Aging and the adrenal cortex.

Aging in humans is accompanied by an increase in adrenal glucocorticoid secretion and a decline in adrenal androgen synthesis and secretion. The intense interest in adrenal function in aging individuals in recent years is in large measure related to the potential impact of cortisol excess in the development of cognitive impairment and hippocampal neuronal loss, and to the desire to provide hormone replacement and healthy aging. Although the preliminary data is tantalizing, solid scientific evidence are not at hand. It is apparent that both issues are extremely complex. Dehydroepiandrosterone (DHEA) and its 3 beta-sulfate are fascinating molecules, including their synthesis and actions in the brain. Recent studies have shown that DHEA-sulfate (DHEA-S), but not DHEA, activates peroxisome proliferator-activated receptor alpha (PPAR alpha) in the liver, an intracellular receptor belonging to the steroid receptor superfamily. Thus, DHEA-S may serve as a physiological modulator of liver fatty acid metabolism and peroxisomal enzyme expression, and thereby may contribute to the anticarcinogenic and chemoprotective properties of this intriguing class of endogenous steroids. The life-sustaining role of adrenal cortisol secretion and its regulation of metabolism via catabolic actions may be modulated by its partner DHEA and DHEA-S. During the anabolic growth period (childhood and early adulthood) the body is exposed to relatively high levels of DHEA/DHEA-S but to relatively or absolutely high levels of cortisol during infancy and the aging phase. The cortisol/DHEA-S ratio during the life span follows a U-shape curve, which may be telling us to explore these two critical adrenal steroids in tandem.

Effects of lifestyle and body composition on the ovary.

Reduction of metabolic fuel availability below the critical level by food restriction or increased expenditure is appropriately accompanied by activations of multiple neuroendocrine-metabolic changes resulting in anovulation and amenorrhea, an important device for endogenous hypothalamic contraception. This reproductive strategy in women is required because of the enormous nutritional demand for reproductive success.

The effect of six months treatment with a 100 mg daily dose of dehydroepiandrosterone (DHEA) on circulating sex steroids, body composition and muscle strength in age-advanced men and women.

OBJECTIVE: The biological role of the adrenal sex steroid precursors--DHEA and DHEA sulphate (DS) and their decline with ageing remains undefined. We observed previously that administration of a 50 daily dose of DHEA for 3 months to age-advanced men and women resulted in an elevation (10%) of serum levels of insulin-like growth factor-I (IGF-I) accompanied by improvement of self-reported physical and psychological well-being. These findings led us to assess the effect of a larger dose (100 mg) of DHEA for a longer duration (6 months) on circulating sex steroids, body composition (DEXA) and muscle strength (MedX). SUBJECTS AND DESIGN: Healthy non-obese age-advanced (50-65 yrs of age) men (n = 9) and women (n = 10) were randomized into a double-blind placebo-controlled cross-over trial. Sixteen subjects completed the one-year study of six months of placebo and six months of 100 mg oral DHEA daily. MEASUREMENTS: Fasting early morning blood samples were obtained. Serum DHEA, DS, sex steroids, IGF-I, IGFBP-1, IGFBP-3, growth hormone binding protein (GHBP) levels and lipid profiles as well as body composition (by DEXA) and muscle strength (by MedX testing) were measured at baseline and after each treatment. RESULTS: Basal serum levels of DHEA, DS, androsternedione (A), testosterone (T) and dihydrotestosterone (DHT) were at or below the lower range of young adult levels. In both sexes, a 100 mg daily dose of DHEA restored serum DHEA levels to those of young adults and serum DS to levels at or slightly above the young adult range. Serum cortisol levels were unaltered, consequently the DS/cortisol ratio was increased to pubertal (10:1) levels. In women, but not in men, serum A, T and DHT were increased to levels above gender-specific young adult ranges. Basal SHBG levels were in the normal range for men and elevated in women, of whom 7 of 8 were on oestrogen replacement therapy. While on DHEA, serum SHBG levels declined with a greater (P < 0.02) response in women (-40 +/- 8%; P = 0.002) than in men (-5 +/- 4%; P = 0.02). Relative to baseline, DHEA administration resulted in an elevation of serum IGF-I levels in men (16 +/- 6%, P = 0.04) and in women (31 +/- 12%, P = 0.02). Serum levels of IGFBP-1 and IGFBP-3 were unaltered but GHBP levels declined in women (28 +/- 6%; P = 0.02) not in men. In men, but not in women, fat body mass decreased 1.0 +/- 0.4 kg (6.1 +/- 2.6%, P = 0.02) and knee muscle strength 15.0 +/- 3.3% (P = 0.02) as well as lumbar back strength 13.9 +/- 5.4% (P = 0.01) increased. In women, but not in men, an increase in total body mass of 1.4 +/- 0.4 kg (2.1 +/- 0.7%; P = 0.02) was noted. Neither gender had changes in basal metabolic rate, bone mineral density, urinary pyridinoline cross-links, fasting insulin, glucose, cortisol levels or lipid profiles. No significant adverse effects were observed. CONCLUSIONS: A daily oral 100 mg dose of DHEA for 6 months resulted in elevation of circulating DHEA and DS concentrations and the DS/cortisol ratio. Biotransformation to potent androgens near and slightly above the range of their younger counterparts occurred in women with no detectable change in men. Given this hormonal milieu, an increase in serum IGF-I levels was observed in both genders but dimorphic responses were evident in fat body mass and muscle strength in favour of men. These differences in response to DHEA administration may reflect a gender specific response to DHEA and/or the presence of confounding factor(s) in women such as oestrogen replacement therapy.

Effects of [norleucine27]growth hormone-releasing hormone (GHRH) (1-29)-NH2 administration on the immune system of aging men and women.

Aging in humans is associated with the decline of functional activities of the GH-insulin-like growth factor I (IGF-I) axis and the immune system. Because lymphocytes express GH-IGF-I, as well as GHRH and their respective receptors, restoration of this axis in age-advanced individuals, by the administration of GHRH, may enhance immune cell function. This hypothesis was tested by a single blind randomized placebo-controlled trial of 5 months duration, in which healthy elderly subjects (10 women, 9 men) self-administered sc nightly placebo for 4 weeks, followed by 16 weeks of [norleucine27]GHRH (1-29)-NH2 at a dose of 10 micrograms/kg. Fasting (0800 h-0900 h) blood samples were obtained for immune studies and for measurements of serum concentrations of IGF-I and soluble interleukin (IL)-2 receptor. GH pulsatility was determined in blood samples obtained at 10-min intervals for 12 h (2000 h-0800 h). Freshly isolated peripheral lymphocytes were analyzed by flow cytometric analysis for determination of lymphocyte subsets and monocytes. Mitogen stimulation responses, natural killer cell number and cytotoxicity, basal and stimulated IL-2 secretion from cultured lymphocytes, and IL-2 and IL-2R messenger RNA expression were measured. These studies were conducted at baseline, after placebo, and during GHRH analog administration at 4 and 16 weeks. Treatment with GHRH analog resulted in a significant increase (107 and 70% in men and women, respectively) in the 12-h integrated GH secretion (P < .05) and serum IGF-I levels (28%) (P < .001) in both men and women by 4 weeks and lasted 12 weeks for IGF-I and 16 weeks for GH. Activation of the immune system occurred in both sexes within 4 weeks. A 30% increase (P < .001) in lymphocytes expressing the transferrin receptor (CD71) and in monocytes (CD14) (P < .05) occurred within 4 weeks. By 16 weeks, there was a significant increase (30%) in B cells (CD20) (P < .01), in cells expressing the T cell receptor alpha/beta (20%) (P < .01), and T cell receptor gamma/delta (40%) (P < .0001). There were no changes in the number of T cells (CD3), T cell subsets (CD4, CD8), or natural killer cell (CD57) over the treatment period. The increase in B cell number was associated with enhanced responsiveness (50%) to the B cell mitogens: pokeweed mitogen (P < .01 or better) and Staphylococus aureus cells (P < .001), and a transient increase at 4 weeks in circulating IgG (P < .0001), IgM, and IgA (P < .001). T cells were functionally activated, as evidenced by a 50% increase in responsiveness to phytohemagglutinin (P < .01 or better), 70% increase in the number of lymphocytes expressing the IL-2 receptor (IL-2R) (CD25) (P < .001), and enhanced IL-2R messenger RNA expression and basal IL-2 secretion (50%) (P < .05) at 16 weeks of treatment. Furthermore, circulating soluble IL-2 receptor rose significantly (15%) (P < .05) within 4 weeks of treatment and remained elevated for the duration of the study. There were no sex differences in the immune response to GHRH analog and no adverse effects. These results indicate that GHRH analog administration has profound immune-enhancing effects and may be of therapeutic benefit in states of compromised immune function.

Inappropriate gonadotropin secretion in polycystic ovary syndrome: influence of adiposity.

In recent years, there has been uncertainty concerning the association of inappropriate gonadotropin secretion (high LH and normal FSH) and the polycystic ovary syndrome (PCOS). In the present study, we ascertained the influence of body composition on LH pulsatile parameters in 33 PCOS and 32 normal cycling (NC) women across a wide range of body mass index (BMI, 19-42 kg/m2). Twenty four-hour pulsatile parameters for serum LH (10-min sampling) and pituitary gonadotropin responses to i.v. bolus GnRH (10 micrograms) were evaluated. Fasting (0800 h) FSH and steroid hormone concentrations and 24-h mean insulin levels were determined. Insulin sensitivity (SI) was assessed by rapid i.v. glucose tolerance test in a subset of 28 PCOS and 29 NC subjects. Our results showed that BMI, an indicator of relative adiposity, had a significant negative impact on 24-h mean LH pulse amplitude (r = -0.63, P < 0.001) and the peak increment of LH in response to GnRH stimulation (r = -0.41; P = 0.02) for PCOS but not NC women. In contrast, 24-h LH pulse frequency was uniformly increased (40%) in PCOS as compared with NC women independent of BMI. In PCOS women, the blunting of pulse amplitude with increasing BMI resulted in a decline in 24-h mean LH levels (r = -0.63, P < 0.001) and the ratio of LH/FSH (r = -0.44, P = 0.02) not seen in NC. With BMI < 30 kg/m2, 24-h mean LH values for PCOS women were greater than the normal range for NC in 95% (18/19) of cases, whereas 24-h LH levels failed to discriminate PCOS from NC women in 43% (6/14) of obese (BMI > 30 kg/m2) PCOS women. Thus, the diagnostic value of LH determinations is retained for PCOS women with BMI < 30 kg/m2. For screening purposes, the mean of two LH values in samples collected at 30-min intervals was found to have a discriminatory power equal to that of the 24-h mean. These findings suggest that 1) BMI negatively influences LH pulse amplitude in PCOS women principally by an effect at the pituitary level; 2) accelerated LH pulse frequency in PCOS women is not influenced by BMI and represents a basic component of hypothalamic dysfunction in PCOS women; and 3) BMI does not influence gonadotropin secretion in normal cycling women. Thus assessments of basal LH levels and the LH/FSH ratio in hyperandrogenic anovulatory women are clinically meaningful when BMI is taken into account. Investigations to define the factor(s) that link adiposity and the attenuation of LH pulse amplitude in PCOS women would add further understanding of this complex neuroendocrine-metabolic disorder.

Expression of genes encoding corticotropin-releasing factor (CRF), type 1 CRF receptor, and CRF-binding protein and localization of the gene products in the human ovary.

Recently, the presence of immunoreactive corticotropin-releasing factor (IrCRF) in the thecal-stromal cells of the human ovary and the ability of CRF to suppress estrogen production by human granulosa cells in vitro have been reported. To understand the functional role of ovarian CRF requires characterization of the human ovarian CRF system, which includes CRF, type 1 CRF receptor (CRF-R1), and the high affinity CRF-binding protein (CRF-BP). Accordingly, we have examined the ovarian CRF system and the cellular distribution of these proteins and their messenger ribonucleic acids (mRNAs) using immunohistochemistry and in situ hybridization, respectively. Normal ovaries from 10 premenopausal women undergoing hysterectomy with ovariectomy were used in the analyses. IrCRF and its mRNA were localized in thecal cells of small antral and mature follicles. A low abundance of IrCRF and mRNA was also detected in stromal cells of both stages of follicles. Expression of the gene encoding CRF was more prominent in mature follicles than in small antral follicles. CRF-R1 mRNA signal was found exclusively in thecal cells of mature follicles and moderately in small antral follicles. Granulosa cells were devoid of CRF and CRF-R1 mRNAs and proteins. The IrCRF-BP, but not its transcript, was detected in thecal cells and luman of capillary vessels of the thecal/stromal compartment of mature follicles. The absence of CRF-BP gene transcript in human ovarian follicles was confirmed by reverse transcription-PCR, indicating that the IrCRF-BP detected is not derived from the ovarian transcript and suggesting that the presence of IrCRF-BP and luman of capillary vessels in the thecal compartment originates from the peripheral circulation. Thecal cells of mature follicles, relative to those of small antral follicles, exhibited an intensive immunostaining and mRNA signal for 17 alpha-hydroxylase (P450c17) indicative of androgen biosynthesis. We conclude that the thecal compartment of the human ovary contains a CRF system endowed with CRF and CRF-R1 and the blood-derived CRF-BP. Granulosa cells are devoid of the CRF system. The parallel increases in intensity of CRF, CRF-R1, and 17 alpha-hydroxylase proteins and gene expression with follicular maturation suggest that the intraovarian CRF system may play an autocrine role in androgen biosynthesis with a downstream effect on estrogen production by the granulosa cells. The functionality of the ovarian CRF system may be conditioned by the relative presence of circulating CRF-BP by virtue of its ability to compete with CRF for the CRF receptor.

Serum leptin levels in women with polycystic ovary syndrome: the role of insulin resistance/hyperinsulinemia.

Polycystic ovary syndrome (PCOS) is associated with chronic anovulation, hyperandrogenemia, insulin resistance (IR)/hyperinsulinemia, and a high incidence of obesity. Thus, PCOS serves as a useful model to assess the role of IR and chronic endogenous insulin excess on leptin levels. Thirty-three PCOS and 32 normally cycling (NC) women of similar body mass index (BMI) were studied. Insulin sensitivity (S(I)) was assessed by rapid ivGTT in a subset of 28 PCOS and 29 NC subjects; percent body fat was determined by dual-energy x-ray absorptiometry (DEXA) in 14 PCOS and 17 NC. Fasting (0800 h) and 24-h mean hourly insulin levels were 2-fold higher (P < 0.0001), and S(I) was 50% lower (P = 0.005) in PCOS than in NC, while serum androstenedione (A), testosterone (T), 17-alpha hydroxyprogesterone (17OHP), and estrone (E1) levels were elevated (P < 0.0001), and sex hormone-binding globulin (SHBG) levels were decreased (P < 0.01). Twenty-four hour LH pulse frequency, mean pulse amplitude, and mean LH levels were elevated in PCOS (P < 0.001) as compared with NC. Serum leptin levels for PCOS (24.1 +/- 2.6 ng/mL) did not differ from NC (21.5 +/- 3.5 ng/mL) and were positively correlated with BMI (r = 0.81) and percent body fat (r = 0.91) for the two groups (both P < 0.0001). Leptin levels for PCOS and NC correlated positively with fasting and 24-h mean insulin levels (r = 0.81, P < 0.0001 for both PCOS and NC) and negatively with S(I) and SHBG levels. Leptin concentrations for PCOS, but not NC, correlated positively with 24-h mean glucose levels and inversely with 24-h mean LH levels and 24-h mean LH pulse amplitude. Leptin levels were not correlated with estrogen or androgen levels for either PCOS or NC, although leptin levels were positively related to the ratios of E1/SHBG and E2/SHBG for both PCOS and NC and to the ratio of T/SHBG for PCOS only. In stepwise multivariate regression with forward selection, only 24-h mean insulin levels contributed significantly (P < 0.01) to leptin levels independent of BMI and percent body fat for both PCOS and NC. Given this relationship and the presence of 2-fold higher 24-h mean insulin levels in PCOS, the expected elevation of leptin levels in PCOS was not found. This paradox may be explained by the presence of adipocyte IR specific to PCOS, which may negate the stimulatory impact of hyperinsulinemia on leptin secretion, a proposition requiring further study.