Further evaluation of the biological activity of the unique gonadotropin-releasing hormone peptide in the guinea pig brain.
In this study we compared the biological activity of a unique form of gonadotropin-releasing hormone (GnRH) in the brain of the guinea pig (gpGnRH) with mammalian GnRH (mGnRH). In gpGnRH, the highly conserved histidine in position 2 (His(2)) and leucine in position 7 (Leu(7)) are substituted by tyrosine and valine, respectively. The gpGnRH was less potent than mGnRH in stimulating the release of luteinizing hormone (LH) in vivo in the guinea pig and displayed only low activity in the rat. The gpGnRH was more rapidly degraded by serum proteolytic enzymes than mGnRH. It is concluded that gpGnRH displays lower biological activity than mGnRH in both rat and guinea pig, which may be due in part to its greater susceptibility to proteolytic degradation besides differences in receptor affinity and/or activation.
Gao
Chang-Qing
CQ
Department of Endocrinology, Ghent University Hospital, 9000 Ghent, Belgium. cgao9@yahoo.com
Fraeyman
Norbert
N
Eertmans
Frank
F
Dhooge
Willem
W
Kaufman
Jean-Marc
JM
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000097:blood / Q000502:physiology*; D006168:Guinea Pigs; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone