title: Serotoninergic stimulation of aldosterone secretion in the rat in vivo: role of the renin-angiotensin system.
abstract: Serotoninergic control of aldosterone secretion in vivo was investigated in conscious rats with indwelling arterial cannulae. Serial blood samples were taken from the animals before and after i.p. administration of 1 ml (4 g/l) 5-hydroxytryptophan (5-HTP), the precursor of serotonin, or saline and they were analysed for 5-HTP, serotonin, 5-hydroxyindoleacetic acid, plasma renin activity (PRA), corticosterone, aldosterone, sodium and potassium concentrations. The role of the renin-angiotensin system was investigated in animals pretreated for 1 week with the angiotensin-converting enzyme inhibitor captopril (25 mg/day). 5-HTP caused a significant increase in all parameters within 45 min except for sodium and potassium. Saline administration showed no significant effect. Captopril pretreatment did not impair the increase in any parameter by 5-HTP, with the exception of the aldosterone response which was significantly attenuated, though not completely. The results show that administration of 5-HTP, which increases serum serotonin levels, stimulates PRA, aldosterone and corticosterone secretion. Captopril pretreatment inhibits the aldosterone response, suggesting that the aldosterone stimulatory properties of 5-HTP require the presence of angiotensin II, although it is unclear whether it acts in a mediatory or permissive capacity. The failure of captopril to inhibit the aldosterone response completely suggests the involvement of other mechanisms such as the hypothalamo-pituitary adrenal axis or a direct action of serotonin on the adrenal.
authors.affiliation: Department of Medicine, Western General Hospital, Edinburgh.
authors.forename: E
authors.initials: E
authors.lastname: Davies
authors.forename: S
authors.initials: S
authors.lastname: Rossiter
authors.forename: C R
authors.initials: CR
authors.lastname: Edwards
authors.forename: B C
authors.initials: BC
authors.lastname: Williams
mesh_terms: D006916:5-Hydroxytryptophan / Q000097:blood / Q000494:pharmacology*; D000450:Aldosterone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D002216:Captopril / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood; D006897:Hydroxyindoleacetic Acid / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000097:blood; D012964:Sodium / Q000097:blood; D013268:Stimulation, Chemical; D013997:Time Factors
chemical_list: D012701:Serotonin; D000450:Aldosterone; D006897:Hydroxyindoleacetic Acid; D002216:Captopril; D012964:Sodium; D006916:5-Hydroxytryptophan; D012083:Renin; D011188:Potassium; D003345:Corticosterone