IMMUNOHISTOCHEMICAL LOCALIZATION OF ENDOTHELIN-1 IN NONNEOPLASTIC ANDNEOPLASTIC ADRENAL-GLAND TISSUE

Endothelin (ET)-1 is a 21-amino acid peptide with potent vasopressor a nd vasocontrictive properties. Biochemical studies suggest that this-p eptide occurs in adrenal glands, where it influences steroid hormone p roduction. However, we have found no report of the topographical distr ibution of this peptide. The localization of ET-1 immunoreactivity in non-neoplastic (37 cases) and neoplastic adrenal glands (48 cases) was investigated with a sensitive immunohistochemical technique applied t o routinely processed tissue specimens. ET-1 immunoreactivity was regu larly seen in the cortex, especially in the zona fasciculata and to a varying extent also in the other two zones, but not in the medulla. Th e immunoreactive material appeared in the cytoplasm mostly in the form of vacuolar structures but also as grains. Focally, the cell membrane also showed immunoreactive staining. In the zona reticularis the immu noreactivity appeared mainly as cytoplasmic grains. Most cortical aden omas displayed numerous immunoreactive cells. The immunoreactivity in the tumour tissue appeared in the same forms as in normal cortex, but the reactive products were generally fewer in number. No obvious diffe rences in immunostaining were seen between the aldosterone- and cortis ol-producing adenomas or the non-functioning ones. Three of the ten ca rcinomas contained immunoreactive cells, but they were few, appearing focally and the ET-1 immunoreactive structures were seen as 'dust-like ' material. The difference in immunoreactivity between the benign and the malignant cortical neoplasms may be of diagnostic value. Functiona lly our results support a relationship between ET-1 and steroid regula tion in non-neoplastic cortical tissue.