Influence of diazepam on rat cardiac noradrenergic innervation in response to noise stress.

The effects of pretreatment with a benzodiazepine (diazepam) on the cardiovascular system of rats exposed to noise were evaluated. Animals were given diazepam before noise treatment; time exposure was one and six consecutive hours. Examination of preparations (corresponding portions of right atrium and ventricle), obtained using the histofluorescence method, showed that noise treatment increased the density of noradrenergic pattern. In diazepam-pretreated tissues the fluorescent fibres resulted to be thinner and less numerous, in particular after one hour of noise exposure. Our present data demonstrate that diazepam exerts a protective action on the heart, more evident after one hour of treatment.