[Immunohistochemical identification of adrenomedullin in adrenal diseases]

Adrenomedullin (ADM) is a hypotensive peptide isolated from human pheochromocytoma tissue. In order to identify the pathophysiological effects of ADM on the etiology of adrenal diseases which can induce hypertension, the localization of immunoreactive adrenomedullin (ir-ADM) in adrenal tissue of subjects with normal adrenal and patients with different adrenal diseases was investigated by means of immunohistochemical staining.

Peroxidase anti-peroxidase complex method was undertaken in the tissue of human adrenal cortex (n = 10) and medulla (n = 10)of subjects with normal adrenal, as well as in the tissue of pheochromocytoma (n = 31), primary aldosteronism including adrenocortical adenoma (n = 13) and hyperplasia (n = 9), Cushing's syndrome including adrenocortical adenoma (n = 12), hyperplasia (n = 10), carcinoma (n = 4) and non-functional adrenocortical carcinoma (n = 7).

Positive immunohistochemical staining of ir-ADM was observed in all the cases of normal adrenal medulla and 16 of the 31 cases of pheochromocytoma. The intensity of immunohistochemical staining of ir-ADM in the majority of pheochromocytoma was lower than that in normal adrenal medulla (P < 0.01). The number of pheochromocytoma cases with positive staining in paroxysmal hypertensive group was higher than that in sustained hypertensive group (P < 0.05). Negative immunohistochemical staining was found in all the cases of normal human adrenal cortex, adrenocortical adenoma, hyperplasia and carcinoma.

It is suggested that heterogeneous of localization of ir-ADM in pheochromocytoma tissue may be correlated to the diversity of blood pressure in patients with pheochromocytoma. The pathophysiological effects of ADM on the etiology of pheochromocytoma should be further investigated.