Effects of hypophysectomy and immobilization stress on S-adenosylmethionine levels in rat adrenal glands

Rat adrenal S-adenosymethione (SAM) levels and phenylethanolamin-N-methltransferase (PNMT) activity were measured under conditions of hypophysectomy and stress. A new dual-label radioenzymatic assay for SAM is presented which eliminates problems found to exist with previous methods. Strain-specific differences in both PNMT and SAM were found, as well as sex differences in SAM levels. Immobilization stress resulted in an increase in adrenal SAM and PNMT activity, while hypophysectomy decreased both. The distribution of SAM between cortex and medulla did not change with either hypophysectomy or stress. Hypophysectomized Fisher rats were found to be capable of increasing PNMT activity in the absence of increased SAM levels.