Simvastatin is an inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase, the key enzyme in the synthesis of cholesterol, recently introduced in the therapy of hypercholesterolemic patients. Cholesterol is the precursor of the biosynthesis of steroid hormones; thus, a reduction of the availability of cholesterol in the adrenal and testicular cells may reduce the synthesis of corticosteroids and androgens. To establish whether chronic therapy with simvastatin interferes with the integrity of the hypothalamic-pituitary-adrenal axis and with the adrenal and testicular reserve, we administered simvastatin orally in a single-day 10 mg dose for 6 months in 8 mildly hypercholesterolemic male patients. At weeks 0, 6 and 24 of treatment we evaluated the lipids, the activity of the hypothalamic-pituitary-adrenal axis by means of the Corticotropin-Releasing Hormone (CRH) test, the adrenal reserve by means of the Corticotropin rapid test and, finally, the testicular reserve by means of the Human Chorionic Gonadotropin (HCG) test. Total cholesterol and LDL-cholesterol were significantly reduced by Simvastatin, while the HDL-cholesterol and triglycerides did not change significantly. The hormonal responses to CRH, ACTH and HCG tests at weeks 6 and 24 of treatment were comparable to those obtained in basal conditions. We conclude that Simvastatin, while effective in reducing total and LDL-cholesterol in hypercholesterolemic male patients, did not interfere with hypothalamic-pituitary-adrenal axis activity or with basal and stimulated adrenal and testicular steroidogenesis.

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The aim of the present study was to test whether the serotoninergic system may be involved in the well known reduced growth hormone (GH) response to insulin-induced hypoglycaemia (IIH) in obese patients. Ten obese women and 10 normal-weight control women underwent three IIH tests, at 14-day intervals: the first in basal conditions, the other two after randomized administration of a serotoninergic drug, fenfluramine (FF, 120 mg/day for 7 days) and FF plus ritanserin (RIT, 30 mg/day for the first 2 days and 20 mg/day on the following days). Ritanserin is a new selective 5-HT2 blocker receptor agent. Both controls and obese patients showed similar normal basal GH levels before each test and insulin administration always effectively reduced glucose levels to values lower than 2-2 mmol/l. In the controls, the expected GH increase to IIH (peak value 56 f 13.4 mU/1, AUC 234.4 f 55 mU/min/ml) was unaffected by FF administration (peak value 43 f 11.4;AUC 216.8 f 34.8). In response to the first IIH, the obese patients showed a significantly lower GH increase than in the case of the controls (peak valut 2 1 -4 f 4.6 mU/1, P < 0.02; AUC 93.2 f 18.6, P < 0.02). However, in comparison with the basal test, FF administration significantly ( P < 0.00 1) enhanced GH response to insulin hypoglycaemia (peak value 33.4 f 4; AUC 150 f 14.6), reaching values not significantly different from those of the controls. This effect was completely antagonized by RIT administration (peak value 18 f 5; AUC 85.6 f 2 1). In conclusion, the reduced GH response to insulin hypoglycaemia in obese women has been confirmed in the present study. However, the restoration of the hormonal response obtained after FF administration in obese patients only, which is effectively antagonized by RIT, strongly suggests the involvement of the serotoninergic system in this impaired

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To evaluate whether low DHEA-S levels are predictors of cortical origin, benignity and hormonal activity in incidentally detected adrenal masses, thirty-five patients with adrenal incidentalomas were studied. All patients were operated on and the diagnosis was histologically confirmed. Basal endocrine workup included plasma determination of cortisol before and after dexamethasone (1 mg overnight), plasma ACTH (08:00 h), 17-OH-progesterone, testosterone and potassium, standing plasma renin activity and aldosterone, supine and standing plasma noradrenaline and adrenaline. If necessary, we performed dexamethasone suppression tests at low (2 mg) and high (8 mg) doses, or the loperamide test (16 mg os) for evaluation of glucocorticoid activity and the glucagon test (1 mg i.v.) for exploring adrenal medulla function. Plasma DHEA-S was measured in all patients and the results were compared to those obtained in controls matched for age, sex and menopausal status. Suppression of DHEA-S was found in 11 out of 35 patients (31.5%). However, this hormonal finding occurred in 50% of the extracortical adrenal lesions, while in proven cortical adenomas (no. = 19) it was detected in only 5 patients (26.3%). Sensitivity, specificity, diagnostic accuracy and positive predictive value of low DHEA-S in indicating a cortical origin of the mass were 0.27, 0.0, 0.25, and 0.80. In malignancies (no. = 6) low DHEA-S levels were found in 1 out of 2 metastases and never in cortical carcinomas. Sensitivity, specificity, diagnostic accuracy and positive predictive value of low DHEA-S in indicating a benign form were 0.34, 0.83, 0.42, and 0.91. Six out of 19 patients with cortical adenomas showed signs of hypothalamic-pituitary adrenal (HPA)-axis dysfunction. Low DHEA-S levels were found in 50% of adenomas with HPA-axis abnormality and in 15.3% of adenomas without hormonal activity. Sensitivity, specificity, diagnostic accuracy, and positive predictive value of low DHEA-S levels in indicating hormonal activity of the mass were 0.50, 0.84, 0.73, and 0.60. Our data indicate that the association between low DHEA-S levels and adrenal incidentalomas is frequent. Low DHEA-S appears to be a poor predictor of hormonal activity with low sensitivity and specificity in respect of cortical origin and benignity of the mass. In conclusion, our results show that DHEA-S measurement does not offer relevant clinical information in the management of adrenal incidentalomas.

In order to demonstrate the suggested failure of the serotoninergic system in human obesity and to evaluate the role of central serotoninergic activity in prolactin (PRL) and thyroid stimulating hormone (TSH) release in this condition, 13 euthyroid obese and 9 healthy women of normal weight were studied. A TRH test (200 micrograms i.v.) was performed before and after administration of fenfluramine (FF) 60 mg b.d. for 14 days. In the controls, FF did not modify the expected significant increase in PRL induced by TRH. In obese patients, however, the PRL levels was significantly increased after TRH, but the increase was less than in the controls. After FF, the PRL response to TRH was larger than in the pretreatment phase, with values similar to those observed in normal subjects. In neither group FF did change the TSH-stimulating effect of TRH, but the hormonal response in obese patients was greater than in the controls. The restoration of the responsiveness of PRL to TRH after central serotoninergic stimulation confirms the hypothesis that a failure of the serotoninergic system may occur in human obesity. Since FF does not interfere with the secretory pattern of basal and stimulated TSH in normal or obese subjects, the serotoninergic system does not seem to play a major role in the control of TSH secretion.

These findings confirm that there is a physiological relationship between the serotoninergic and the opioidergic systems in the control of PRL secretion and show that this interaction is not present in obese subjects. Our data provide indirect proof of the functional impairment of these two systems in human obesity.