Age-Related Effects of Dexamethasone Administration in Adrenal Zona Reticularis

Abstract

Suppression of adrenocorticotropic hormone results in reduced adrenal steroid output, adrenocortical cell atrophy, and apoptosis in young rats. To verify such effects during aging, dexamethasone was injected into rats for 3 days at five different ages; at day 4, adrenals and blood were collected for morphologic and corticosterone assay. Adrenal structure was similar at all ages, but in dexamethasone-injected animals there were ultrastructural features of apoptosis and a higher percentage of TUNEL and caspase-3-labeled nuclei and cytoplasm; their corticosterone decreased significantly. In both groups, there was age-related decrease in the percentage of apoptotic cells, significant only in dexamethasone-injected rats. The data suggest that aged adrenocortical cells are less susceptible to the lack of adrenocorticotropic hormone (ACTH), possibly as a result of their decreased functional ability.