The effects of tunicamycin on anterior pituitary hormone producing cells in the rat.

An electron microscopic study was performed to clarify the effects of tunicamycin, a glycosylation inhibitor, on rat anterior pituitary cells. Tunicamycin (10, 50, and 100 micrograms/250 g B.W.) was intraperitoneally injected into rats, which were sacrificed 24 hrs later. Protein hormone producing GH and prolactin cells, and ACTH cells which are known to have a glycosylated precursor, showed no recognizable ultrastructural changes. TSH cells and gonadotrophs, both of which secrete glycoprotein hormones consisting of alpha and beta subunits, showed remarkable dilatation of the rough endoplasmic reticulum, and decreased numbers of secretory granules. These results suggest that the role of glycosylation in TSH cells and gonadotrophs may have a different biological significance from that in ACTH cells.