Incorporation of [3H] leucine into brain stem protein fractions: the effect of a behaviorally active, N-terminal fragment of ACTH in hypophysectomized rats.

In hypophysectomized rats, the incorporation of [3H] leucine into rat brain stem protein, measured 5 min after injection of the precursor into the diencephalon, was decreased. Chronic treatment of these rats with the N-terminal fragment of ACTH, ACTH1-10 increased the incorporation rate. Brain stem proteins were sequentially extracted with a hypotonic buffer, Triton X-100 and SDS. Analysis of these protein fractions on polyacrylamide gels revealed that hypophysectomy caused a general decrease in leucine incorporation into all protein species studied, whereas treatment of hypophysectomized rats with ACTH1-10 enhanced this incororation into all proteins. Superimposed on these general effects were minor differences found in two protein bands. Thus, removal of the pituitary and subsequent, chronic treatment of rats with ACTH1-10 interferes with overall protein metabolism rather than with certain protein species in particular.