the nerve fibers that supply the external muscle of the human gastrointestinal tract were examined for their immunoreactivity to the neuropeptides enkephalin , neuropeptide y , somatostatin , substance p , and vasoactive intestinal peptide , for tyrosine hydroxylase ( a catecholamine-synthesizing enzyme ) , and for coexistence between immunoreactivities in nerve fibers .
C0027895
neuropeptides
C0027893
neuropeptide y