Change in Heterogeneity of Pituitaly-extractd ProLactin in the Estrogen-induced Adenoma Formation in Rats

Rat pituitary prolactinoma model induced by estrogen was analyzed by two-dimentinal electrophoresis to clarify change in prolactinoma-formation process. Ten week-aged female Wistar rats 150-170gm were used in this study. Long-active 17/β-estradiol (Ovahormone Depot^<[○!R]>) was injected intramusculal once a week. The animals were divided into 6groups by the number of 17β-estradiol injection. They were the group of 0 week (no-injection) (n=12), the group of 2 weeks (n=10), the group of 4 weeks (n=10), the group of 6 weeks (n=8), the group of 8 weeks (n=6), the group of 9 weeks (n=6) (total rat number N=52). Each excised pituitary gland was examined by histological methods (Hematoxylin-eosin staining and prolactin-immunostaining). Pituitary weight and prolactin concentration were measured. Extraced prolactin was analyzed by two-dimentional electrophoresis. Increase in prolactin positive cells was recognized in the pituitary glands of the group of 2 weeks by histological study. And adenoma-resembling findings were recognized in the pituitary gralds of the group of 6 weeks. Pituitary weight was markedly increased in the group of 8 weeks, and thereafter the pituitary weight was not increasing. Therefore, pituitary glands of 8 and 9 weeks were diagnosed as adenoma, and pituitary glands of the groups of 2, 4 and 6 weeks as hyperplasia by histological examination. Two-dimentional electrophoretical patterns fro the groups of 0-6 weeks were same. In the goups of 8 and 9 weeks, however, 3 spots neighboring the cathode in 7spots of molecular weight 24-25kD were disappeared. This disappearance of 3 spots was thought to be the change due to adenoma formation, and useful to distinguish between pituitary hyperplasia and adenoma.

エストロゲン

プロラクチン産生線種

2次元電気泳動法

プロラクチン多様性