Responsiveness of thyroid C cells to steroid hormones

Abstract

The role of steroids in the regulation of thyroid C and mast cells function of rats and pigs were the object of our experimental examinations. The argyrophil properties, morphometric characteristics and subcellular organization of C and mast cells in rats of both sexes after neonatal estradiol-dipropionate treatment were studied. A special attention has been paid to the changes in the structure of thyroid C cells after a chronical treatment of aged (2-year-old) rats with estradiol-dipropionate or testosterone propionate. Besides, the structure and function of immunoreactive C cells of middle-aged female rats (14-month-old) chronically treated with estradiol-dipropionate, calcium or a combination of estradiol-dipropionate and calcium were observed. Serum levels of calcitonin, osteocalcin, parathormone and beta-estradiol were also measured using RLA method. It has been observed that neonatal estradiol-dipropionate treatment expresses a long-term stimulative effects on rat thyroid C cells, while chronic treatment of middle-aged rats with estradiol-dipropionate acts inhibitory on these cells. In addition, the argyrophil properties and ultrastructural characteristics of C cells of male pigs treated with estradiol--dipropionate and progesterone in combination or castrated on the first day of life and sacrificed 6 or 8 months later were investigated. A slower rate of specific protein synthesis and secretion of porcine C cells after sex steroids treatment was observed.