Electroconvulsive shock increases tyrosine hydroxylase activity in the brain and adrenal gland of the rat.

A single application of electroconvulsive shock produced a rapid but short-lasting increase in tyrosine hydroxylase activity above control values in the rat adrenal medulla and striatum. After repeated electroconvulsive shock treatment (once per day for 7 days), tyrosine hydroxylase activity increased significantly in the locus ceruleus, nucleus of the tractus solitarius, hippocampus, cerebellum, and frontal cortex and remained elevated for 4 to 8 days. Adrenal tyrosine hydroxylase activity increased 1 day after the termination of repeated electroconvulsive shock treatments and remained elevated for at least 24 days, possibly reflecting the establishment of a new and higher steady-state level of catecholamine biosynthesis in the adrenal. These findings suggest that the persistent changes in tyrosine hydroxylase activity produced by repeated electroconvulsive shock may be a factor contributing to the long-lasting antidepressant effects of this treatment.