Delayed increase of adrenal TH and PNMT activities following cold stress in the mouse

Abstract

The activities of the adrenal enzymes tyrosine hydroxylase (TH) and phenylethanolamine- N-methyltransferase (PNMT) were found to be elevated when mice were subjected to 4°C ambient temperature. Only a single hr of cold exposure is required to achieve increased activity, provided that the measurements are made 12 hr after the cold exposure is initiated. After the cold stress is terminated, PNMT activity remain elevated for 12 hr. TH demonstrates a biphasic response to cold exposure, as the enzyme activity shows a second increase 12 hr after the stress has ended. The data indicates that short periods of stress result in demonstrated biochemical changes that persist long after the stress has ended.