DISTRIBUTION OF CATECHOLAMINERGIC NEUROTRANSMITTERS AND RELATED RECEPTORS IN HUMAN BRONCHUS-ASSOCIATED LYMPHOID TISSUE

Background: The functions of the bronchus-associated lymphoid tissue (BALT) are under the control of the autonomic nervous system ( sympathetic and parasympathetic nerve fibers). Objectives: The relationships between the adrenergic nerve fibers and beta-adrenergic receptors were studied in the human BALT with the aim to demonstrate a probable neuromodulation. Methods: Morphological observations ( staining with hematoxylineosin and scanning electron microscopy images) were carried out on samples of human BALT harvested during autopsies. Moreover, histochemical staining for norepinephrine ( adrenaline = adrenergic nerve fibers) as well as for other catecholamines was performed. Finally, beta-adrenergic receptors were stained by means of a beta-blocking, radiolabeled drug ( pindolol I-125). All our data were submitted to morphometric analysis ( quantitative analysis of images and statistical analysis of data). Results: Our results provide direct evidence of the presence and distribution of catecholaminergic nerve fibers and related beta-adrenergic receptors in BALT. beta-Adrenergic receptors are present above all in the most richly innervated part of the BALT, and are, therefore, in close relationship with their related adrenergic nerve fibers. Conclusions: Studies on the distribution of adrenergic neurotransmitters and related beta-adrenergic receptors in the human BALT are the first step for the demonstration of a probable neuromodulation of BALT. Copyright (C) 2004 S. Karger AG, Basel.