Involvement of cAMP but not PKA in the increase of corticosterone secretion in rat zona fasciculata-reticularis cells by aging

✍ Scribed by Ming-Jae Lo; Paulus S. Wang

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 147 KB
• Volume: 85
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.10106

✦ Synopsis

Abstract

The effects and mechanisms of aging on corticosterone secretion in zona fasciculata‐reticularis (ZFR) cells of ovariectomized (Ovx) rats were studied. Young (3‐month) and old (24‐month) female rats were Ovx for 4 days before decapitation. ZFR cells were isolated and incubated with different hormones or reagents at 37°C for 30 min. Aging increased the basal secretion of corticosterone both in vivo and in vitro. The adrenocorticotropin (ACTH)‐, forskolin‐, 3‐isobutyl‐l‐methylxanthine (IBMX)‐, 8‐bromo‐adenosine 3′,5′‐cyclic monophosphate (8‐Br‐cAMP)‐, and ovine prolactin (oPRL)‐stimulated release of corticosterone by ZFR cells was greater in old than in young Ovx rats. H89, an inhibitor of protein kinase A (PKA), decreased the production of corticosterone in ZFR cells from young but not old Ovx rats. Forskolin‐, or IBMX‐induced production of cAMP was greater in old than in young Ovx animals, which correlated with the increase of corticosterone production by aging. The activity of 11β‐hydroxylase that converts deoxycorticosterone (DOC, 10^−9^ or 10^−8^ M) to corticosterone in rat ZFR cells was decreased by age. However, the corticosterone production in response to high dose of DOC (10^−7^ M) was indifferent between young and old groups. These results suggest that aging increases corticosterone production in Ovx rats via a mechanism in part associated with an increase of adenylyl cyclase activity and a decrease of phosphodiesterase activity, and then an increase of the generation of cAMP, but not related to either PKA activity or 11β‐hydroxylase. J. Cell. Biochem. 85: 35–41, 2002. © 2002 Wiley‐Liss, Inc.