Changes in gonadotrophin-releasing hormone and LH in Japanese quail during the first few days of photostimulation

Abstract

ABSTRACT Castrated Japanese quail responded to a single long day with a five- to eightfold increase in plasma LH levels. A rise in LH secretion appeared 19–24 h after dawn and LH levels were still increased 3 days later, despite the fact that the birds had been returned to a short daylength. Pituitary LH content decreased, reflecting these changes in secretion, although significant falls in content were only found 36–96 h after dawn, when LH secretion was maximal. Hypothalamic gonadotrophin-releasing hormone content was not altered. One interpretation of this is that increased synthesis of the peptide compensates fully for the increased secretion. J. Endocr. (1987) 113, 419–422