Isolation and characterization of chicken hypothalamic luteinizing hormone-releasing hormone

A peptide having gonadotropin-releasing activity was isolated in a yield of 2.5 μg from an extract of 2,000 chicken hypothalami. The biopotency was monitored using rat anterior pituitary cell culture system. The peptide differs from mammalian Luteinizing Hormone-Releasing Hormone (LH-RH) in its behavior during chromatographic separation (ionexchange and high performance liquid chromatography) and in its reaction towards anti-LH-RH antiserum directed against the C-terminal region of the LH-RH molecule. The peptide (chicken LH-RH) stimulates secretion of both LH and FSH from rat anterior pituitary cells. The biological potency of this peptide was about 4 % of that of the authentic decapeptide estimated in the rat anterior pituitary system. The amino acid composition is (Ser, Pro, Glx₂, Gly₂, Leu, Tyr, His, Trp), which differs from mammalian LH-RH only in that one Arg residue is replaced by a Glx residue. Based on the behavior on CM cellulose chromatography and the reaction towards anti-LH-RH antiserum, one possible structural candidate for this peptide (chicken LH-RH) is Gln⁸]-LH-RH.