Human hypothalamic growth hormone releasing factor (GRF): evidence for two forms identical to tumor derived...

Human hypothalamic growth hormone-releasing factor (GRF) was purified by gel filtration and reverse-phase HPLC. Bioassay and two radioimmunoassays of different specificity revealed the presence of two major forms of GRF-activity which coelute with human pancreas GRFs, hpGRF-44-NH2 and hpGRF-40 previously characterized in pancreas tumors. The bioactive material coeluting with hpGRF-44-NH2 is recognized by two antibodies which are directed against the amidated COOH-terminal sequence and the central portion of the GRF-44 peptide. The bioactive GRF which coelutes with hpGRF-40 reacts only with the antibody directed against the central portion of hpGRF. These data strongly suggest that the human hypothalamus contains the same major forms of GRF that were identified in pancreas tumors responsible for acromegaly in the absence of a pituitary tumor.