Aging effects on the secretion of corticosterone in male rats

Background: The effects of aging on zona fasciculata-reticularis (ZFR) cell function in male rats were studied. Methods: Male rats 3, 6, and 22 months of age were divided into three group s, and collagenase-disperse ZFR cells were isolated and incubated with adre nocorticotropin (ACTH), I-bromo-adenosine 3':5'-cyclic monophosphate (8-Br- cAMP), ovine prolactin (oPRL), deoxycorticosterone (DOC), or 3-isobutyl-1-m ethylxanthine (IBMX) at 37 degreesC for 1 hour, Corticosterone concentratio ns in cell media and cAMP production in ZFR cells were measured by radioimm unoassay, Protein expression of PRL receptor in ZFR cells were analyzed by Western blot. Results: The basal levels of plasma and medium corticosterone were higher i n 22-month-old than in 3-month-old rats. In contrast, the release of cortic osterone in response to ACTH, 8-Br-cAMP, and DOC was lower in 22-month-old than in 3-and 6-month-old rats. Aging decreased the oPRL-stinulated release of corticosterone but increased the protein expression of PRL receptor in ZFR cells, The basal levels of intracellular cAMP increased with age. Howev er, the ACTH-stimulated production of intracellular cAMP decreased in 22-mo nth-old compared with 3- or 6-month-old rats. The increment of cAMP accumul ation in ZFR cells after administration of IBMX was greater in 22-month-old than in 3- or 6-month-old rats. Conclusions: These results suggest that the aging effects on the production of corticosterone in rat ZFR cells is associated with change of the genera tion of cAMP, the activity of 11 beta -hydroxylase and the protein expressi on of PRL receptor.