A study of TSH-synthesis of spontaneous hypertensive rats by electron microscopic morphometry and autoradiography

In order to compare the functional state of the anterior pituitary of spontaneously hypertensive rats (SHR) with that of nonmotensive Wistar Kyoto rats (WKR), the anterior pituitary was examined by morphometry and autoradiography at the level of electron microscopy. The relative number and the relative volume of thyrotrophs in the anterior pituitary were significantly greater in SHR compared with age-matched WKR at 0, 7, 30-33 days and 10 months of age, while the relative number of somatotrophs in SHR was significantly smaller at 1 and 10 months of age. Electron microscope autoradiographic analysis of uptake of 3H-lysine by thyrotrophs of both strains at the age of approximately one month showed that 3H-lysine was incorporated into protein and transported finally to secretory granules which migrated to near the cell membrane to be discharged. Silver grains were significantly more numerous over the thyrotrophs of SHR than over those of WKR at 30 min, 1 h, and 4 h after the injection of 3H-lysine. The present study has ascertained morphologically than a congenital hypersynthesis of TSH by the anterior pituitary occurs in SHR.