Plasma LH and androgen levels in the red-winged blackbird (Agelaius phoeniceus) treated with a potent GnRH analogue.
1. Low doses of GnRH-A (0.01-0.10-1.0 micrograms) given during the annual testes growth period did not clearly affect plasma LH and androgen levels 10 min following the injection. 2. The first injection of high doses of GnRH-A (2.0-10.0-20.0 micrograms) markedly increased plasma LH and androgen levels measured 10 min following the injection. The increase in plasma LH level was dose-dependent and the maximal LH level was obtained with 10.0 micrograms of GnRH-A. 3. Impairment of the LH response to GnRH-A was assessed by comparing the first and the fourteenth injection of high doses of GnRH-A. Evidences of pituitary gland desensitization are reported since plasma LH levels were reduced following the fourteenth injection in all groups. 4. Plasma androgen levels following high doses of GnRH-A were not clearly affected in red-winged blackbirds.
Raptor Research Center, McDonald College of McGill University, Ste-Anne-de-Bellevue, Qc, Canada.
D
D
Lacombe
A
A
Cyr
P
P
Matton
D000728:Androgens / Q000097:blood*; D000818:Animals; D001717:Birds; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D012621:Seasons; D013737:Testis / Q000254:growth & development; D017329:Triptorelin Pamoate / Q000031:analogs & derivatives*
D000728:Androgens; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; C019176:Tryptal; D007986:Luteinizing Hormone