Sex differences in the LH responses to chicken LHRH-I and -II in the domestic fowl.
Maximal incremental changes in plasma LH were compared in adult hens and cockerels after i.v. injection of chicken (c) LHRH-I (pGlu1-His2-Trp3-Ser4-Tyr5-Gly6-Leu7-Gln8-Pro9-Gly10-N H2) or cLHRH-II (pGlu1-His2-Trp3-Ser4-His5-Gly6-Trp7-Tyr8-Pro9-G ly10-NH2). The LH response to cLHRH-I and -II was more rapid and greater in cockerels than in hens. The potencies of the two decapeptides were the same in cockerels but different in hens. Relative to cLHRH-I, the potency of cLHRH-II was 0.91 (0.6-1.2; 95% confidence limits) in cockerels and 36.5 (16.8-128.6) in hens. The greater potency of cLHRH-II relative to cLHRH-I in the hen than in the cockerel could not be accounted for by sex differences in the half-lives of the decapeptides in the peripheral circulation. The half-lives of both decapeptides in hens and cockerels ranged between 2.42 and 3.77 min. It is concluded that the interaction between LHRH-I and -II and the gonadotrophs is sexually differentiated in the domestic fowl. A new homologous radioimmunoassay was established for cLH. As in other chicken LH radioimmunoassays, there was evidence of cross-reactivity with TSH.
Sharp
P J
PJ
AFRC Institute of Animal Physiology & Genetics Research, Edinburgh Research Station, Roslin, Midlothian.
Dunn
I C
IC
Talbot
R T
RT
D000818:Animals; D002645:Chickens / Q000097:blood*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006207:Half-Life; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D012727:Sex Characteristics
D007987:Gonadotropin-Releasing Hormone; C037700:LHRH, Gln(8)-; D007986:Luteinizing Hormone; C049513:LHRH, His(5)-Arg(6)-Trp(7)-Tyr(8)-; D011761:Pyrrolidonecarboxylic Acid