The role of the pituitary-adrenal system in the footshock-induced increase of [3H]lysine incorporation into mouse brain and liver proteins.

The brains of mice subjected to electric footshocks took up more free [3H]lysine and incorporated more [3H]lysine into protein than did the brains of undisturbed mice, suggesting that footshocks caused increased cerebral protein synthesis. The possible mediation of these effects by hormones of the pituitary-adrenocortical system was investigated. Despite adrenalectomy, footshock treatment still elevated the poolcorrected [3H]lysine incorporation into cerebral protein. Pretreatment with dexamethasone, which greatly suppressed the pituitary-adrenal response to footshocks, prevented the increase in [3H]lysine incorporation. It is suggested that ACTH itself may mediate this stress-induced increase in net free [3H]lysine uptake. Although the lysine uptake response thus appeared to depend upon the presence of the adrenal glands, the response was not mimicked by injection of corticosterone. The response of liver [3H]lysine metabolism was studied in the same experiments. Footshock treatment decreased the net uptake and increased the incorporation into protein, in normal, adrenalectomized and dexamethasone-pretreated mice. Corticosterone did not mimic these effects. Thus, the metabolic response to footshock of liver, unlike that of brain, appeared to be independent of the pituitary-adrenal system.