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Summary Lipofuscin is an autofluorescent and undegradable material, which accumulates in tissues during ageing and under different types of stress. Among these, oxidative stress represents a major trigger for lipofuscin formation. However, prolonged noise exposure is also an effective stressful stimuli. Diazepam may inhibit lipofuscinogenesis in liver and prevent the noise-induced reduction of the steroidogenesis in the adrenal gland. The aim of the study was to ascertain whether chronic noise exposure causes lipofuscin accumulation in mouse testis, and to evaluate the effects of diazepam administration. Eight-week old mice were either exposed for 6 weeks (6 h day−1) to white-noise (group A), or received diazepam (3 mg kg−1, i.p.) before noise exposures (group B), while a further group was used as control (group C). Light fluorescence and transmission electron microscopy revealed lipofuscin in large amounts in the Leydig cells in mice of group A, which concomitantly had low serum testosterone levels; pre-treatment with diazepam occluded both effects. The present study indicates that: (i) chronic noise exposure causes lipofuscin accumulation at the level of the Leydig cells and a decrease in testosterone; (ii) all these effects are suppressed by pre-treatment with diazepam. As the Leydig cells represent the only cellular type of the interstitial testicular tissue having peripheral benzodiazepine receptors, these results could be explained by the capacity of the peripheral benzodiazepine receptors to prevent reactive oxygen species damage and to increase the resistance of these cells to oxidative stress.

Several works have reported that nitric oxide and free oxygen radicals are up-regulated in nasal polyposis. This study aimed to assess the distribution of peroxynitrite in nasal polyps from nonatopic patients. Occurrence of peroxynitrite also was analyzed in relation with eosinophil infiltration and epithelial alterations.Hematoxylin and eosin staining was used for histologic study. Peroxynitrite was assessed by 3-nitrotyrosine immunohistochemistry. Quantitative evaluation was done by measuring the total number of eosinophils, the number of 3-nitrotyrosine-positive eosinophils, and the extension of the various epithelial alterations.Hematoxylin and eosin staining showed that the nasal polyp epithelium is characterized by progressive disruption or squamous metaplasia. In both cases, infiltrating eosinophils were found in the epithelium and lamina propria. The regions featuring epithelial disruption exhibited 3-nitrotyrosine immunostaining in eosinophils and epithelial cells; hematoxylin-and-eosin - stained eosinophils and 3-nitrotyrosine - positive eosinophils showed conspicuous variations in number. Within the regions featuring squamous metaplasia, 3-nitrotyrosine-positive eosinophils were rarely found, and the epithelium exhibited 3-nitrotyrosine only in the superficial cells. In these regions, hematoxylin-eosin - stained eosinophils showed slight variations in number.Peroxynitrite plays a pivotal role in the pathophysiology of nasal polyps. In fact, strong expression of peroxynitrite is associated with epithelial disruption, while poor expression of peroxynitrite is associated with squamous metaplasia. Peroxynitrite could influence afflux of eosinophils in the nasal mucosa; moreover, the total number of eosinophils is not critical in generating alterations of nasal polyp mucosa.