Catecholaminergic nerve fibers in bronchus-associated lymphoid tissue: age-related changes.
Age-related changes of the catecholaminergic nerve fibers of the trachea, bronchial smooth muscle, lung capillaries and bronchus-associated lymphoid tissue (BALT) were studied in male Wistar rats aged 3 months (young), 12 months (adult) and 24 months (old/aged). Catecholamine histo- and immuno-fluorescence techniques were used, associated with image analysis and high pressure liquid chromatography with electrochemical detection of nor-epinephrine (nor-adrenaline). In young rats, blue-green fluorescent nerve fibers supply the trachea-bronchial smooth muscle and tracheal and bronchial glands. These structures are innervated by a delicate network of nerve fibers, being rich in varicosities. Pulmonary capillaries are sparsely innervated. The highest nor-epinephrine concentration was found in the trachea and bronchi, followed by BALT. The density and the pattern of noradrenergic nerve fibers of the trachea-bronchial tree or of the pulmonary vessels were similar in young and adult rats. In aged rats, a loss of noradrenergic nerve fibers, involving primarily the supply to the smooth muscle of the trachea-bronchial tree, was observed. Fluorescence microscopic techniques demonstrated a higher sensitivity than nor-epinephrine assay in detecting changes of the sympathetic nerve supply of the trachea-bronchial tree, pulmonary vessels and BALT. The possible significance of reduced noradrenergic nerve supply of the trachea-bronchial-pulmonary tree in aged rats is discussed.
Cavallotti
C
C
Department of Cardiovascular and Respiratory Sciences, Sezione di Anatomia, Via A. Borelli 50, I-00161 Rome, Italy. cavallotti@uniromal.it
Tranquilli Leali
F M
FM
Galea
N
N
Tonnarini
G
G
D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001980:Bronchi / Q000294:innervation*; D002395:Catecholamines / Q000502:physiology*; D008221:Lymphoid Tissue / Q000294:innervation*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013194:Staining and Labeling
D002395:Catecholamines