Pharmacological stimulation of chromaffin cell proliferation in the adult adrenal medulla.

Many strains of rats develop adrenal medullary hyperplasia and/or neoplasia after chronic administration of a wide variety of pharmacologic agents. The same changes may occur spontaneously in the course of aging. Current evidence suggests that chromaffin cell proliferation in adult rats is regulated by a combination of hormonal and neurogenic signals. Drugs associated with adrenal medullary tumors might act directly or indirectly on the hypothalamic-endocrine axis or the autonomic nervous system to stimulate chromaffin cell proliferation through mechanisms which normally adjust cell number to meet physiological needs. The increased cell turnover rate might be a prelude to other events leading to neoplastic transformation.