ULTRASTRUCTURAL CHANGES OF THYROTROPIC CELLS IN THE DYNAMICS OF EXPERIMENTAL IMMUNOSTIMULATION

The endocrine and immune systems are interrelated via a bidirectional network.Thyroid-stimulating hormone plays a critical role as an endogenous mediator of immune activity. Purpose of study was to determine the dynamics of changes of thyrotropic cells ultrastructure in modeling immunostimulation in mature male rats by subcutaneous injection of imunofan in a dosage 0,7 mg/kg of body weight.The pituitary samples were taken on 1st, 7th, 15th, 30th and 60th, day after treatment and thenfixed in glutaraldehyde for electron microscope. The study showed theincrease of functional activity of the thyrotropic cells. The significant increase of areas of the cells and their nuclei, area of mitochondria and secretory granules was established since 7th day after imunofan treatment.

Pituitary thyrotropic cells are affected by steroid hormones

The pituitary gland is a heterogeneous tissue comprised of several hormone-secreting cells most of which are targeted by sex steroids. Our long-term studies were concentrated on the response of rat pituitary TSH cells to gonadal steroids applied to animals of different age. With this goal, we examined immunoreactive and morphometric, as well as subcellular organization of pituitary TSH cells in rats of both sexes after neonatal and perinatal estradiol-dipropionate (EDP) treatment. The results undoubtedly indicated persistent EDP-related inhibitory changes of tyrotrophs up to the adulthood. At the subcellular level, a delayed differentiation of TSH cells was noticed. Besides, a special attention has been paid to the changes in the structure of immunoreactive TSH cells of middle-aged (14-month-old) rat females, chronically treated with EDP, calcium (Ca) or a combination of EDP and Ca. Based on our results it can be concluded that both EDP and Ca act inhibiting the thyrotrophs under the applied experimental conditions.