Cold-induced increment in rat adrenal gland type II deiodinase is corticosterone dependent

In this study we analyzed whether corticosterone synthesis is involved in the regulation of adrenal gland type II deiodinase (AG-D2) activity during acute cold exposure. Two well-known inhibitors of steroidogenesis, aminoglutethimide (AGT) and metyrapone (MTP), were administered to male Wistar rats maintained either at room temperature or acutely exposed to cold (1 h at 4 degrees C). AG-D2 activity was measured by the radioiodide release method, and corticosterone circulating levels were measured by competitive protein binding assay. Results show that resting corticosterone levels and AG-D2 activity were lower in both AGT- and MTP-treated rats. Furthermore, the phasic increase normally exhibited by AG-D2 activity in response to acute cold stress was blunted in AGT- and MTP-treated animals. Therefore, we conclude that corticosterone synthesis is necessary in preserving the physiologic response of AG-D2 activity to cold exposure.