Age-related changes in the morphology and function of the zona glomerulosa of the rat adrenal cortex.
The age-related changes in the morphology and function of rat adrenal zona glomerulosa (ZG) were investigated by coupled stereological and radioimmunological techniques. For this purpose 4-, 8-, 16- and 24-month-old rats were studied. Aging caused a notable lowering in the plasma aldosterone concentration and a marked decrease in both basal and ACTH- or angiotensin II (ANG-II)-stimulated secretion of collagenase-dispersed ZG cells. Plasma renin activity (PRA) underwent an age-dependent decrease, while the plasma level of ACTH displayed a significant rise. ZG and its parenchymal cells did not evidence any age-related morphologically demonstrable alteration in their growth, nor ZG cells showed any marked ultrastructural change, with the exception of a severe lipid-droplet repletion. This last finding is in keeping with the aging-induced decrease in the secretory activity of ZG cells, inasmuch as lipid droplets are the intra-cellular stores of cholesterol esters, the obligate precursors of steroid hormones in rat adrenals. ACTH and ANG-II are well known to be involved in the maintenance of the growth of rat ZG; thus, the combined impairment of ANG-II production (as evidenced by PRA lowering) and increase in ACTH secretion may maintain unchanged ZG growth during aging.
Belloni
A S
AS
Department of Anatomy, University of Padua, Italy.
Rebuffat
P
P
Malendowicz
L K
LK
Mazzocchi
G
G
Rocco
S
S
Nussdorfer
G G
GG
D000375:Aging / Q000473:pathology*; D000818:Animals; D002452:Cell Count; D008297:Male; D008854:Microscopy, Electron; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D015384:Zona Glomerulosa / Q000502:physiology / Q000648:ultrastructure*