Effects of subacute exposure to noise on the noradrenergic innervation of the cardiovascular system in young and aged rats: a morphofunctional study

Abstract

The effects of subacute noise stress on the noradrenergic pattern and receptor-mediated responses were examined in aorta and atria of young and aged rats. Noise exposure increased the density of noradrenergic fibres and responses to the beta-adrenergic agonist isoprenaline in the cardiac tissue of young animals. In aged rats, the stressing stimulus markedly increased the maximal response to the alpha-agonist on the aortic musculature; on the contrary, a reduced responsiveness to the beta-agonist was observed at the cardiac level, without any noteworthy changes in the noradrenergic pattern in comparison to aged controls. The present results indicate that subacute noise stress induces both morphological and functional modifications of the noradrenergic nervous system and also that after subacute noise stress, morphological changes do not necessarily correspond exactly to functional data; the latter show responses that are more widely differentiated than the morphological ones.

DNA damage associated with ultrastructural alterations in rat myocardium after loud noise exposure.

“…Measurement of NA levels in specific areas of myocardial atrium and ventricle demonstrated the presence of higher amounts of this catecholamine in control tissue from the ventricle compared with that from the atrium (Table 1). Extending what was previously reported on the basis of histofluorescence qualitative measurements (Paparelli et al 1992), the amount of NA and its metabolites dihydroxymandelic acid and vanilmandelic acid in myocardial tissue after noise exposure indicated that loud noise increases NA levels and NA utilization. Increase in extracellular metabolites significantly exceeded increases in NA levels, leading to a significant rise in the turnover index (ratio between extracellular metabolites and NA).…”

“…In particular, here we found that noise exposure produces a significant increase of NA release as measured by myocardial levels of NA and metabolites. This latter finding lends substance to previous observations obtained in noise-exposed rats showing an increased fluorescence in the myocardial tissue as revealed by the histochemical technique of Falck-Hillarp (Paparelli et al 1992). These original findings did not address the functional relevance of an increased myocardial histofluorescence, leaving open the question of whether this was accompanied by increased NA release.…”

“…On the other hand, experimental studies have demonstrated ultrastructural modifications in rat cardiomyocytes mainly involving mitochondria (Paparelli et al 1995;Reuter 1966;Soldani et al 1997;Yatani et al 1999). These subcellular alterations are related to an imbalance in calcium homeostasis , which is supposed to be sustained by increased catecholamine innervation (Breschi et al 1994;Paparelli et al 1992). …”

Effects of loud noise exposure on mouse myocardium: A comparison with the rat

“…In particular, in the rat, heart noradrenergic innervation is reported to increase, following loud noise exposure (Breschi et al, 1994;Paparelli et al, 1992). At the same time, ultrastructural investigation shows that rat cardiomyocytes exhibit several subcellular changes (Paparelli et al, 1995;Soldani et al, 1997a).…”

Noise-Stress-Induced Brain Neurotransmitter Changes and the Effect of Ocimum sanctum (Linn) Treatment in Albino Rats

“…On the other hand, experimental studies have demonstrated ultra structural modifications in rat cardiomyocytes mainly involving mitochondria. These subcellular alterations are related to an imbalance in calcium homeostasis, which is supposed to be sustained by increased catecholamine innervations (1).…”