Plasma levels of luteinizing hormone and of five steroids in photostimulated, castrated and testosterone-treated male and female Japanese quail (Coturnix coturnix japonica)

Sensitive radioimmunassay techniques were developed and valiated to permit the assay in small volumes of quail plasma of five steroids including testosterone, 5alpha-dihydrotestosterone, androstenedione, estradiol and progesterone. The characteristics of the assays are presented. They are then used in a study of plasma steroid levels in male and female Japanese quail following photostimulation, gonadectomy and testosterone therapy. The levels of all steroids are affected by the experimental treatments and some by the sex of the birds. Levels of androgens, estradiol and progesterone after gonadectomy and testosterone therapy are similar in males and females. The differential sensitivity of males and females to the activating effects of testosterone on cloacal gland growth and sexual behavior thus cannot be explained by a differential catabolism of the implanted hormone and must be researched at the level of the target organ for steroid action.