CHANGES IN EXPRESSION OF THE PROLACTIN AND GROWTH-HORMONE GENE DURINGDIFFERENT REPRODUCTIVE STAGES IN THE PITUITARY-GLAND OF TURKEYS

The changes in levels of prolactin (PRL) acid growth hormone (GH) in p lasma and the pituitary gland and their transcripts were measured in t urkey hens at different physiological stages by radioimmunoassay and d ot blot hybridization analysis, respectively. The levels of tPRL mRNA in the pituitary gland increased from those of the immature group to t he egg-laying group, reaching a maximum during the incubation and a mi nimum during the moulting stages. Changes in pituitary levels of PRL a nd PRL mRNA followed a similar trend and consequently were highly corr elated (r(2) = 0.83), whereas a significant but lower correlation was observed between circulating and pituitary levels (r(2) = 0.62). Less significant changes were measured for tGH mRNA, with maximum and minim um levels measured in the pituitaries of egg-laying and non-laying hen s, respectively, These data suggest that although changes in concentra tion of PRL are correlated with the reproductive stage of the turkey h en, coordinate changes in levels of GH are not.