LOCALIZATION OF PROGESTERONE-RECEPTOR IN BRAIN AND PITUITARY OF THE RING DOVE - INFLUENCE OF BREEDING CYCLE AND ESTROGEN

An immunocytochemical method was used in male and female ring doves (S treptopelia risoria) to localize progesterone receptor immunoreactivit y (PR-ir) in the brain and anterior pituitary gland in nonbreeding, in cubating, brooding, and estrogen (E-2)-treated nonbreeding birds. Prog esterone receptor was found in four regions of the brain in males and females: the preoptic area (POA), nucleus preopticus paraventricularis magnocellularis (PPM), nucleus hypothalami lateralis (PLH), and the t uberal region (TR). Quantitative analysis demonstrated that the densit y of cell nuclei containing PR-ir in the POA, PPM, and PLH in brooding birds was significantly higher than in E-2-treated doves or in birds at other stages of the reproductive cycle. The density of PR-containin g cell nuclei in the TR of male ring doves was significantly higher on day 1 of incubation than in nonincubating males. In brooding birds, t here was a significant decrease in PR-ir in the TR, particularly in th e ventral region where nuclei containing PR-ir disappeared. In the ant erior pituitary gland the density of cell nuclei containing PR-ir was higher in females than in males at the onset of incubation. E-2 treatm ent resulted in an increase in the density of PR-containing cell nucle i in both males and females. Brooding females had a lower concentratio n of PR-containing cell nuclei than did females at other stages of the breeding cycle. It is suggested that progesterone receptor in the POA mediates the expression of incubation behavior while progesterone rec eptor in the TR is involved in the control of neuroendocrine function. The source of estrogen which increases PR appears to be of central ne rvous origin in the male and may be predominantly peripheral in the fe male. (C) 1997 Academic Press.