AJP - Renal Physiology, Vol 249, Issue 6 891-F897, Copyright © 1985 by American Physiological Society
Ontogeny of triamcinolone-acetonide binding sites in outer cortical tissue from rat kidneys
A. Aperia, L. A. Haldosen, L. Larsson and J. A. Gustafsson
The ontogeny of glucocorticoid binding sites and the glucocorticoid hormone
(GC) feedback control of available glucocorticoid binding sites was studied
using the cytosolic fraction of outer cortical tissue obtained from kidneys
in 20- and 40-day-old intact and adrenalectomized rats. Morphometric
analysis showed that this tissue contained 85.7% (20 days) and 88.7% (40
days) of proximal tubular cells. Glucocorticoid binding sites were
determined by [3H]triamcinolone-acetonide (TA) binding and isoelectric
focusing analysis. In intact rats, TA binding sites (fmol/mg DNA) were
significantly higher at 20 (3,624) than at 40 (1,640) days. Adrenalectomy
significantly increased TA binding sites (fmol/mg DNA) at 40 (to 8,445) but
not at 20 days. TA binding sites related to DNA were significantly higher
in 20- than in 40-day-old intact rats and significantly higher in 40- than
in 20-day-old adrenalectomized rats. Serum corticosterone (nM) was not
significantly different in 20- (230) and 40- (189) day-old rats. After in
vivo administration of a synthetic GC, TA binding sites were replenished to
the cytosol after 20-24 h. Prolonged GC treatment (1-60 micrograms X 100 g
body wt-1 X day-1) depressed the replenishment of TA binding sites
significantly more in 40- than in 20-day-old adrenalectomized rats. Kd was
determined in both intact and adrenalectomized 20- and 40-day-old rats and
ranged between 1.30 and 4.33 nM. The steroidal specificity for the TA
binding sites was the same in 20- and 40-day-old rats.(ABSTRACT TRUNCATED
AT 250 WORDS)
