ergoline and Hypoglycemia

The present study was carried out in order to determine whether insulin-induced hypoglycemia exerts its stimulatory effect on plasma concentrations of arginine vasopressin (AVP) by interacting with a serotonergic, a GABA-ergic or an opioid pathway. For this purpose, the effect of the serotonergic antagonist metergoline (10 mg/day for 4 days po), the GABA-ergic agonist sodium valproate (600 mg in three divided doses po) and the opioid-receptor blocker naloxone (10 mg in a iv bolus) on the AVP response during an insulin (0.15 IU/kg bw) tolerance test (ITT) was evaluated in three groups of 6 normal men each. In all men, control ITTs were performed without drug treatments. Basal and ITT-stimulated AVP secretion was not modified by drug administration, suggesting that serotonergic, GABAergic and naloxone-sensitive opioid receptors are not involved in the regulation of AVP secretion in response to insulin-induced hypoglycemia.

Topics: Adrenocorticotropic Hormone; Adult; Arginine Vasopressin; Ergolines; gamma-Aminobutyric Acid; Growth Hormone; Humans; Hypoglycemia; Insulin; Male; Metergoline; Naloxone; Valproic Acid

Topics: Adult; Blood Glucose; Circadian Rhythm; Ergolines; Humans; Hypoglycemia; Insulin; Male; Metergoline; Prolactin

The effect of metergoline, a specific antiserotoninergic drug, on ACTH secretion was investigated in 29 normal volunteers and in 4 patients with increased ACTH production (3 with Addison's disease, 1 with Cushing's disease). In 15 normal subjects, a 4-day treatment with 10 mg daily of metergoline significantly blunted the ACTH response to insulin hypoglycemia. Mean peak ACTH values before and after treatment were, respectively, 333 +/- 39.2 (SE) and 235 +/- 38.8 pg/ml (P less than 0.05). The corresponding values of plasma cortisol were 29.6 +/- 2.96 and 20.5 +/- 2.67 mug/100 ml (P less than 0.05). In contrast, metergoline failed to affect the ACTH response to lysine-vasopressin (LVP) administered iv (8 subjects studied) and im (6 subjects studied). In 3 patients suffering from Addison's disease, an appreciable although not statistically significant lowering of the plasma ACTH levels was noted during metergoline administration. The mean pre- and post-treatment values of plasma ACTH in these patients were, respectively, 1116 +/- 192.2 and 666 +/- 100.8 pg/ml, 4240 +/- 50.0 and 3398 +/- 368.0 pg/ml, and 431 +/- 44.0 and 352 +/- 23.9 pg/ml. In one patient with Cushing's disease caused by a pituitary adenoma, metergoline did not appreciably modify plasma ACTH levels. Taken together, these results lend support to the concept of a physiological stimulating effect of serotonin on ACTH secretion. Moreover, they are compatible with the view that serotonin exerts its action chiefly at the hypothalamic level while LVP promotes ACTH release by a primary action on the pituitary.

Topics: Addison Disease; Adrenocorticotropic Hormone; Adult; Cushing Syndrome; Ergolines; Female; Humans; Hydrocortisone; Hypoglycemia; Hypothalamo-Hypophyseal System; Insulin; Lypressin; Male; Metergoline; Middle Aged; Serotonin; Serotonin Antagonists; Vasopressins

Topics: Adolescent; Adrenal Glands; Adult; Animals; Bromocriptine; Dogs; Ergolines; Female; Humans; Hydrocortisone; Hypoglycemia; Hypothalamo-Hypophyseal System; Insulin; Male; Rats; Receptors, Dopamine

Topics: Adenosine Triphosphate; Adrenergic alpha-Antagonists; Anesthesia; Animals; Bemegride; Brain; Bromine; Carotid Arteries; Cocaine; Dipyridamole; Dogs; Electroencephalography; Energy Transfer; Ergolines; Femoral Artery; Hypoglycemia; Hypotension; Hypoxia; Lactates; Ligation; Male; Malonates; NAD; Nicotinic Acids; Pyruvates; Time Factors; Urethane