Pituitary prolactin cells in diabetic rats induced by the injection of streptozotocin.

Ultrastructural changes of prolactin (PRL) cells in streptozotocin (STZ)-induced diabetic rats treated with or without insulin were observed by means of conventional and immunocytochemical electron microscopic studies. With progress of diabetic state, the number, cellular outline and secretory granules of PRL cells were decreased, and the organella were changed into atrophic. Granule extrusion was frequently observed in PRL cells of diabetic rats but was not seen after the injection of insulin to the diabetic rats in spite of recovering the ultrastructural features of organella in PRL cells. The above results may suggest that the injection of insulin to diabetic rats stimulates the activity of PRL cells but suppresses the PRL release from PRL cells.