adrenocorticotropin-zinc and Body-Weight

Body fat mass and nutrition influence secretion of the adrenocortical hormones--aldosterone and cortisol--via several mechanisms. However, there are no data on adrenocortical function following widely prescribed mild diet-induced weight loss (10%) in obese subjects. In the present study, 25 healthy obese volunteers (BMI 32.9+/-4.3 kg/m (2)) followed a 30% calorie restricted diet over 12 weeks. Hypothalamic-pituitary-adrenal (HPA) axis function was assessed by 24-hour urine free cortisol/cortisone and a 1 mcg ACTH stimulation test with measurement of total and free cortisol and corticosteroid-binding globulin (CBG). The renin-angiotensin-aldosterone system (RAAS) was assessed by measurement of plasma aldosterone and renin under salt depleted (30 mmol/d) and loading (250 mmol/d) conditions. Volunteers' weight fell by 8.5+/-0.8 kg (8.9+/-0.7%) and seated systolic blood pressure fell by 8.7+/-2.7 mmHg and diastolic blood pressure by 7.0+/-1.4 mmHg (p<0.01). Plasma aldosterone and renin levels fell significantly with weight loss (aldosterone: 853+/-156-635+/-73 pmol/l; renin: 35.4+/-7-24+/-3 mU/l, both p<0.05). The volunteers were relatively salt insensitive (mean arterial pressure change with salt intake: 4 mmHg) and this was not affected by weight loss. Moderate weight loss had no effect on 24-hour urine free cortisol/cortisone, or on basal, or ACTH-stimulated free and total cortisol, or CBG. Hence this conventional weight loss program reduces blood pressure and activity of the RAAS via an effect on renin release. Despite various described influences of fat mass and energy restriction on HPA axis function, there were no changes in basal and stimulated HPA axis function with moderate weight loss. There may be a threshold effect of weight loss/energy restriction required to alter HPA axis function, or moderate weight loss may lead to a counterbalanced effect of stimulatory and inhibitory influences on HPA axis function.

Topics: Adult; Aged; Aldosterone; Blood Pressure; Body Weight; Caloric Restriction; Cosyntropin; Cross-Over Studies; Diet, Reducing; Female; Humans; Hydrocortisone; Male; Middle Aged; Obesity; Pituitary-Adrenal System; Renin; Renin-Angiotensin System; Sodium Chloride, Dietary; Transcortin; Weight Loss

Hypercortisolism was induced in rats by the administration of a corticotrophin analogue (Synacthen depot). The effect of this treatment during different periods was studied in normally fed and overnight-fasted rats. The activity of liver-type lipases, i.e., of lipases similar to the heparin-releasable lipase of rat liver (liver lipase), was determined in the adrenal gland and in the liver. Short-term (16 h) treatment had no effect on the lipase activity in the adrenal gland. During prolonged treatment, however, the lipase activity rose to 600-700% of control values in 10 days and from then on remained constant. The effect was similar in fed and overnight-fasted rats. The lipase activity in the liver decreased upon Synacthen administration. In the fed rats a decrease of 25% of the initial value was found after 16 h, 40% after 3 days and 50% after 20 days of treatment. In overnight-fasted rats the lowering of the lipase activity was less marked than in fasted controls. Serum lipid levels and high-density lipoprotein (HDL) subclass concentrations were also measured. The cholesterol concentration in the lipoproteins with a density greater than 1.050 g/ml (HDL) was elevated in rats treated for 3-20 days. If the rats were treated for longer than 10 days, overnight fasting led to a normalization of the HDL-cholesterol levels. After separation of the HDL into two subfractions, a relatively 'light' apolipoprotein E-rich fraction and a more 'heavy' apolipoprotein A-I-rich fraction, in fed and fasted animals treated with Synacthen for 3 days both HDL subfractions were elevated. After 10 days treatment only the apolipoprotein A-I-rich HDL fraction was still enhanced in both fed and fasted rats.

Topics: Adrenal Glands; Adrenocorticotropic Hormone; Animals; Body Weight; Chemical Phenomena; Chemistry; Cholesterol; Cosyntropin; Fasting; Lipase; Lipoproteins, HDL; Liver; Male; Rats; Rats, Inbred Strains