Ovarian involvement in the suppression of luteinizing hormone in the incubating turkey (Meleagris gallopavo).
A series of experiments were conducted to elucidate the role of the ovary in incubation behavior-associated luteinizing hormone (LH) suppression. Ovariectomy (Ovx) increased (p < 0.05) serum LH levels in nonphotostimulated, laying and photorefractory turkeys but not in incubating birds (p > 0.05). Ovx had no effect on intramuscularly injected mammalian luteinizing hormone-releasing hormone (4 micrograms/kg i.m.)-induced LH in incubating hens, but enhanced the LH response in laying hens. Serum LH and prolactin (Prl) were unaffected by Ovx, and nest deprivation (ND) decreased Prl levels (p < 0.05) with no effect on serum LH of incubating turkeys. However, serum LH increased (p < 0.05) and Prl decreased in Ovx-ND birds. Prl mRNA abundance (11.9 +/- 1.2 ng/microgram total RNA) decreased following Ovx (3.4 +/- 0.4 ng/microgram total RNA) or ND (3.6 +/- 0.5 ng/microgram total RNA). Nest deprivation increased LH beta mRNA (2.5-fold) which was further increased (4.8-fold) by Ovx. Hypothalamic GnRH-I and GnRH-II contents increased (p < 0.05) in Ovx-ND turkeys. We conclude that serum LH suppression during incubation behavior requires ovarian participation acting synergistically with elevated Prl and/or nesting stimulus on hypothalamic GnRH, and that the concentration fo LH beta mRNA may be a limiting factor in LH secretion.
el Halawani
M E
ME
Department of Animal Science, University of Minnesota, St. Paul 55108.
Silsby
J L
JL
Foster
L K
LK
Rozenboim
I
I
Foster
D N
DN
D000818:Animals; D005260:Female; D007031:Hypothalamus / Q000378:metabolism; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism*; D009425:Nesting Behavior / Q000502:physiology*; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology*; D010058:Oviposition / Q000502:physiology; D010775:Photic Stimulation; D010902:Pituitary Gland / Q000378:metabolism; D011388:Prolactin / Q000097:blood / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012636:Secretory Rate / Q000502:physiology; D014422:Turkeys / Q000502:physiology*
D012333:RNA, Messenger; D011388:Prolactin; D007986:Luteinizing Hormone