Serum estrone (E1) and 17beta-estradiol (E2) were noted to be 2-fold elevated in a group of morbidly obese men. Urinary E1 and E2 production rates were elevated in proportion to the degree of obesity, with values as high as 127 and 157 micrograms/day, respectively. Although serum testosterone (T) concentrations were reduced in obese men, averaging 348 +/- 35 vs. 519 +/- 42 ng/dl in lean controls, the dialyzable T fractions were elevated and, hence, the calculated free T concentrations were normal in obese men. Further, the obese men exhibited normal serum LH, FSH, and T responses to clomiphene citrate, indicating intact hypothalamic-pituitary-Leydig cell axes. MCRs of T and peripheral conversion of T to E2 and androstenedione (delta) to E1 were all increased in obese men in proportion to the percentage above ideal weight. Although the obese mean exhibited increased blood levels and production rates of estrogens, there were no signs of feminization, increased T-estrogen-binding, globulin levels, or suppressed basal gonadotropin levels, suggesting a lack of biological effect. We postulate that obese men exhibit defective estrogen receptors, leading to decreased T-estrogen-binding globulin, increased clearance of androgenic hormones, and elevated estrogen production rates.

Androgen and estrogen production rates were examined in 29 morbidly obese women with upper or lower body obesity. Although blood production rates of testosterone (T), dihydrotestosterone, and androstenedione (A4) were elevated in all of these women, those with upper body obesity (waist-height ratios, greater than 0.85) had higher T and production rates than women with lower body obesity (waist-height ratio less than 0.75). A4 was equally elevated in women with upper and lower body obesity. Peripheral aromatization of A4 to estrone (E1) averaged 1.67% in women with upper body obesity, but was elevated at 2.54% in women with lower body obesity. Urinary E1 production rates averaged 466 +/- 295 nmol/day (172 +/- 109 micrograms/day) in women with upper body obesity. Thus, women with lower body obesity had higher E1 production rates due entirely to increased peripheral aromatization. Women with upper body obesity were observed to have higher serum T and estradiol (E2) levels than women with lower body obesity. Further, upper body obesity was associated with decreased levels of sex hormone-binding globulin (16.1 +/- 5.7 nmol/L vs. 18.9 +/- 6.1 in women with lower body obesity). As a result, free T levels averaged 98.8 +/- 39.2 pmol/L in women with upper body obesity vs. 82.2 +/- 33 in women with lower body obesity. Similarly, serum free E2 levels were higher in women with upper body vs. lower body obesity. The data demonstrate that sex hormone production and metabolism are different in morbidly obese women with these differing phenotypes. Women with upper body obesity have higher androgen production rates and higher free T and free E2 levels, whereas women with lower body obesity make increased amounts of E1 from peripheral aromatization. The biological significance of increased aromatization may be offset by increased free E2 levels in women with upper body obesity.

As bstract. We have tested the participation of endogenous opiate pathways in the negative feedback actions of gonadal steroids on pulsatile properties of luteinizing (LH) hormone release in normal men. To this end, sex steroid hormones were infused intravenously at dosages that under steady state conditions selectively suppressed either the frequency or the amplitude of the pulsatile LH signal. The properties of pulsatile LH secretion were assessed quantitatively by computerized analysis of LH series derived from serial blood sampling over 12 h of observation.When the pure (nonaromatizable) androgen, 5-a-dihydrotestosterone, was infused continuously for 108 h at the blood production rate of testosterone, we were able to achieve selective inhibition ofLH pulse frequency akin to that observed in experimental animals after low-dosage androgen replacement. Under these conditions, serum concentrations of testosterone and estradiol-1 7,3 did not change significantly, but serum 5a-dihydrotestosterone concentrations increased approximately two-to threefold, with a corresponding increase in levels of its major me- tabolite, 5a-androstan-3a, 17f-diol. In separate experiments, the infusion of estradiol-1 7#3 at its blood production rate over a 4.5-d interval selectively suppressed LH pulse amplitude without influencing LH pulse frequency. Estrogen infusion increased serum estradiol-1 73 levels approximately twofold without significantly altering blood androgen concentrations. We then used these schedules of selective androgen or estrogen infusion to investigate the participation of endogenous opiates in the individual inhibitory feedback actions of pure androgen or estrogen on pulsatile LH release by administering a potent and specific opiate-receptor antagonist, naltrexone, during the infusions.Our observations indicate that, despite the continuous infusion of a dosage of 5a-dihydrotestosterone that significantly suppresses LH pulse frequency, co-administration of an opiate-receptor antagonist effectively reinstates LH pulse frequency to control levels. Moreover, during the infusion of a suppressive dose of estradiol-1 73, opiate receptor blockade significantly augments LH pulse frequency and increases LH peak amplitude to control levels.Thus, the present studies in normal men demonstrate for the first time that the selective inhibitory action of a pure androgen on LH pulse frequency is effectively antagonized by opiate-receptor blockade. This pivotal oW servation indicates that opiatergic and androgen-dependent mechanisms specifically and coordinately control the hypothalamic pulse generator for gonadotropin-re- We conclude that the negative feedback actions of gonadal steroids are integrally coupled to endogenous opiate pathways and that such functional coupling is ultimately expressed at least in part at the level of the hypothalamic pulse generator for GnRH. These observations suggest a model for the proximate regulation of gonadotropin secretion in man, in which the regulatory actions of two major inhibitory systems...

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