Immunocytochemical correlates of an extrapituitary adrenocortical regulation in man.

Investigations reviewed in this article provide cytochemical and functional support for a significant involvement of extrapituitary factors in human adrenocortical functions. Among these factors neural messengers may play a crucial role in the adrenocortical regulation, arising from specifically coded postganglionic neurons with both, extrinsic and intrinsic locations, as well as from chemically characteristic afferent neurons. The close association of varicose transmitter segments with steroid hormone synthesizing cells and their occurrence at arteries and sinusoid capillaries are indicative for both direct and indirect regulatory mechanisms on cortical functions. The immunohistochemical presence of neuropeptides and cytokines in endocrine and/or immune cells of the human adrenal medulla and cortex as well as specific binding sites on steroidogenic cells indicate the modulatory implication of additional short-paracrine- and ultrashort-autocrine-feedback loops on cortical cell proliferation and steroid metabolism. The summarized data suggest that basal endocrine influence of the hypothalamo-pituitary axis on adrenocortical growth and functions in man is controlled by the nervous system that also regulates local fine-tuning of human cortical activity.