In-vitro and in-vivo responses to chicken LHRH-I and chicken LHRH-II in male turkeys (Meleagris gallopavo).
Stimulation of male turkey hypophyses in vitro with chicken (c)LHRH-I, cLHRH-II or porcine (p)LHRH (0.1 mumol/l) using a perifusion technique caused an increase in the release of LH. In this system, cLHRH-II was approximately 2.5-fold more potent than cLHRH-I and pLHRH which were equipotent. The difference was due to a greater amplitude of the response but not to a prolonged action. Hypophyseal desensitization to a subsequent stimulation was induced when the interval between stimulations was 30 min, but did not occur when lengthened to 60 or 120 min. Injection of a single dose of cLHRH-I or -II in vivo at doses of 10 and 0.1 nmol/kg body weight stimulated increases in the plasma concentration of LH and testosterone initiated within 1 or 10 min after injection respectively. As in vitro, cLHRH-II induced greater responses, which were dose-related, than did cLHRH-I. However, this difference could be attributed to a greater potency of cLHRH-II and to a more prolonged action. At the 10 nmol/kg dose, the shape of the LH response to cLHRH-II changed; it consisted of an initial increase during 10 min after injection, followed by a more sustained phase during which LH levels were still increasing between 20 and 60 min after injection. In contrast, after an injection of cLHRH-I at doses of 10 or 0.1 nmol/kg or cLHRH-II at a dose of 0.1 nmol/kg, LH levels were at a peak within 5 min and thereafter declined gradually.(ABSTRACT TRUNCATED AT 250 WORDS)
Guémené
D
D
I.N.R.A. Station de Recherches Avicoles, Nouzilly, France.
Williams
J B
JB
D000818:Animals; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000502:physiology; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D009924:Organ Culture Techniques; D010902:Pituitary Gland / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D013739:Testosterone / Q000378:metabolism; D014422:Turkeys / Q000378:metabolism*
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; C037700:LHRH, Gln(8)-; D007986:Luteinizing Hormone; C047717:LHRH, His(5)-Trp(7)-Tyr(8)-; D011761:Pyrrolidonecarboxylic Acid