title: Effects of high salt intake on brain AT1 receptor densities in Dahl rats.
abstract: To assess effects of dietary salt on brain AT1 receptor densities, 4-wk-old Dahl salt-sensitive (Dahl S) and salt-resistant (Dahl R) rats were fed a regular (101 mumol Na/g) or high (1,370 mumol Na/g)-salt diet for 1, 2, or 4 wk. AT1 receptors were assessed by quantitative in vitro autoradiography. AT1 receptor densities did not differ significantly between strains on the regular salt diet. The high-salt diet for 1 or 2 wk increased AT1 receptor binding by 21-64% in the Dahl S rats in the subfornical organ, median preoptic nucleus, paraventricular nucleus, and suprachiasmatic nucleus. No changes were noted in the Dahl R rats. After 4 wk on a high-salt diet, increases in AT1 receptor binding persisted in Dahl S rats but were now also noted in the paraventricular nucleus, median preoptic nucleus, and suprachiasmatic nucleus of Dahl R rats. At 4 wk on the diet, intracerebroventricular captopril caused clear decreases in blood pressure only in the Dahl S on the high-salt diet but caused largely similar relative increases in brain AT1 receptor densities in Dahl S and R on the high-salt diet versus regular salt diet. These data demonstrate that high salt intake rapidly (within 1 wk) increases AT1 receptor densities in specific brain nuclei in Dahl S and later (by 4 wk) also in Dahl R rats. Because the brain renin-angiotensin system only contributes to salt-induced hypertension in Dahl S rats, further studies are needed to determine which of the salt-induced increases in brain AT1 receptor densities contribute to the hypertension and which to other aspects of body homeostasis.
authors.affiliation: Hypertension Unit, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario, Canada K1Y 4W7.
authors.forename: Jun Ming
authors.initials: JM
authors.lastname: Wang
authors.forename: Shereeni J
authors.initials: SJ
authors.lastname: Veerasingham
authors.forename: Junhui
authors.initials: J
authors.lastname: Tan
authors.forename: Frans H H
authors.initials: FH
authors.lastname: Leenen
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects* / Q000502:physiology; D002216:Captopril / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007276:Injections, Intraventricular; D007672:Kidney Cortex / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D008297:Male; D051381:Rats; D020303:Rats, Inbred Dahl; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*
chemical_list: D000959:Antihypertensive Agents; D044140:Receptor, Angiotensin, Type 1; D017673:Sodium Chloride, Dietary; D002216:Captopril