Identification and secretion of gamma-endorphin and beta-endorphin-like peptides from the neurointermediate pituitary of the rat.

Gamma-endorphin (gamma E) and related peptides were chromatographically identified in extracts of neurointermediate (NIL) pituitary. When extracts of this tissue were purified and subjected to HPLC in order to identify gamma E-related peptides gamma E, des-tyrosine gamma E, des-enkephalin-gamma E, and alpha-N acetyl gamma E co-elutable peptides were evident. Perifusates of dispersed NIL tissue were also shown to contain beta E and gamma E-immunoreactivity, and the secretion of both was suppressed by exposure of the tissue to dopamine. This study provides evidence of the endogenous presence and secretion of pharmacologically active gamma E-related peptides by the intermediate lobe of the rat pituitary.