APPEARANCE OF BETA-5-MICROGLOBULIN IN RAT HYPOTHALAMIC MAGNOCELLULAR NEURONS AFTER HYPOPHYSECTOMY

To clarify the relationship between neuronal cell degeneration and MHC class-I complex expression, we have immunohistochemically examined th e distribution of beta(2)-microglobulin in the hypophysectomized rat h ypothalamus. In the sham-operated control rats, positive stainings wer e distributed only in blood vessels in the hypothalamic areas where ma gnocellular neurons were localized. Three days after hypophysectomy, p ositive stainings appeared in a large number of magnocellular neurons in the paraventricular and supraoptic nuclei. Most of such beta(2)-mic roglobulin-positive cells were simultaneously stained with antivasopre ssin serum. The pattern of distribution of positive cells and the inte nsity of the stainings remained unchanged at least until the 14th day. These morphological findings suggest that the process of degeneration of hypothalamic magnocellular neurons after hypophysectomy is a usefu l model to investigate the role of MHC class I complex in the brain.