Abstract: Growth hormone releasing factor(GRF), growth hormone releasing peptide (GHRP) and GRF-antagonist (GRF-AN, D-Arg2-GRF₄₄) were synthesized by solid phase method and their biological activities were detected in our institute. The result is reported as follows. 1.Both GHRP and GRF can stimulate human pituitory growth hormone (GH) secretion in vitro and in vivo.2.Both GHRP and GRF can stimulate bovine pituitory GH secretion in vitro,3.GHRP can accelerate immature rats growth 4 GRF-AN has a strong seletive inhibition on human and animal pituitory GH secretion stimulated by GRF and has no inhibition on GH secretion stimulated by GHRP. Our investigation indicates that both GRF and GHRP can stimulate pituitary GH secretion, but there is a essential distinction in mechanism between them.

Key words: growth hormone-releasing factor, growth hormone-releasing peptide, growth hormone, rat