Distribution of catecholaminergic neurotransmitters and related receptors in human bronchus-associated lymphoid
Carlo Cavallotti1, Paolo Bruzzone, Gianfranco Tonnarini
1Department of Cardiovascular and Respiratory Sciences, University of Rome La Sapienza, Rome, Italy. cavallotti@uniroma1.it
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 hematoxylin-eosin 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 125I). 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.
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