AREGU May 45/5

Engeland, W. C., and B. K. Levay-Young. Changes in the glomerulosa cell phenotype during adrenal regeneration in rats. Am. J. Physiol. 276 (Regulatory Integrative Comp. Physiol. 45): R1374–R1382, 1999.—In situ hybridization was used to examine cellular differentiation during rat adrenal regeneration, defining zona glomerulosa [cytochrome P-450 aldosterone synthase (P-450aldo) mRNA positive], zona fasciculata [cytochrome P-450 11b-hydroxylase (P-45011b) mRNA positive], or zona intermedia [negative for both but 3bhydroxysteroid dehydrogenase (3b-HSD) mRNA positive]. After unilateral adrenal enucleation with contralateral adrenalectomy (ULE/ULA), the expression of all mRNA was reduced at 2 days. From 5 to 10 days, P-45011b and 3b-HSD mRNA increased while P-450aldo remained low; at 20 days, all mRNA were increased. From 2 to 10 days, cells adjacent to the capsule showed intermedia cell differentiation; by 20 days, the subcapsular glomerulosa cells reappeared. This suggests that after enucleation the glomerulosa dedifferentiates to zona intermedia. The experiment was repeated in rats where the postenucleation ACTH rise was prevented. Rats underwent ULE with sham ULA (ULE/SULA) or ULE/SULA with ACTH treatment. Adrenals from ULE/SULA rats expressed increased P-450aldo mRNA at 10 days and reduced P-45011b mRNA and adrenal weight at 30 days. ACTH treatment reversed the pattern toward that seen in ULE/ ULA. These findings show that the enucleation-induced dedifferentitation of the glomerulosa cell may result in part from elevated plasma ACTH and that prevention of dedifferentiation may result in impaired regeneration.