title: Evidence for direct inhibitory effects of dopamine on zona glomerulosa secretion of 18-hydroxycorticosterone in rhesus monkeys.
abstract: This study was designed to more selectively investigate the dopaminergic regulation of 18-hydroxycorticosterone (18-OHB) and aldosterone production by the adrenal zona glomerulosa. Mature rhesus monkeys received either an infusion of dopamine (2 micrograms/kg/min) or 5% dextrose (0.2 ml/min) over a 60 min period (N=6). Dopamine had no effect on plasma levels of renin activity, cortisol, corticosterone, aldosterone or blood pressure. However, dopamine suppressed (p less than 0.05) plasma 18-OHB levels from a baseline of 31.6 +/- 3.5 ng/dl to 23.6 +/- 2.1 ng/dl at 60 min after onset of infusion. This observation is in agreement with some studies in humans but differs from others in which no depression in 18-OHB was observed following dopamine infusion. Dopamine infusion markedly (p less than 0.001) suppressed plasma PRL levels by 30 min after onset of infusion. Corticosteroid responses to metoclopramide (200 micrograms/kg) after dexamethasone 1 mg im every 6 h X 5 days or placebo treatment (vehicle im every 6 h X 5 days) was then evaluated. Dexamethasone significantly suppressed basal cortisol, corticosterone, 18-OHB and aldosterone. Although dexamethasone blunted the prolactin response, it did not inhibit the aldosterone response to metoclopramide. The 18-OHB response to metoclopramide was increased (p less than 0.01) following dexamethasone treatment. Following dexamethasone suppression, 18-OHB levels were still lowered (p less than 0.05) by dopamine infusion. These results suggest that dopamine selectively inhibits zona glomerulosa production of 18-OHB and aldosterone in rhesus monkeys.
mesh_terms: D015069:18-Hydroxycorticosterone / Q000378:metabolism*; D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism*; D000305:Adrenal Cortex Hormones / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003345:Corticosterone / Q000031:analogs & derivatives*; D003907:Dexamethasone / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D018492:Dopamine Antagonists; D008253:Macaca mulatta; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology; D012084:Renin-Angiotensin System / Q000187:drug effects
chemical_list: D000305:Adrenal Cortex Hormones; D018492:Dopamine Antagonists; D015069:18-Hydroxycorticosterone; D003907:Dexamethasone; D008787:Metoclopramide; D004298:Dopamine; D003345:Corticosterone