Noise-induced duodenal lesions: a light and electron microscopy study of the lesions of the rat duodenal mucosa exposed to low frequency noise

Abstract

Background and aims: Non-auditory effects of noise, including digestive disorders have long being reported. Low frequency noise (LFN) is considered to be responsible to most of non-auditory effects of noise and is widely spread in modern societies. Only a few studies were designed to evaluate these noise-induced digestive alterations. The pathogenesis of duodenal ulcers and erosions is complex and noise may be an environmental co-factor. The aim of the present study was to investigate the morphological injury of LFN-exposed duodenal mucosa.

Materials and methods: Five groups of Wistar rats were exposed to continuous LFN, during increasing periods, since 1 to 13 weeks. A control group was kept in silence. Duodenal specimens were studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: We disclosed several changes in LFN-exposed rats: on LM, mucosa showed superficial erosions of the epithelial layer, degeneration, picnosis and cell death, with no inflammation. On SEM, epithelium presented displacement of cells and unequal distribution of microvilli, with coalescence and fusion. On TEM, microvilli were irregularly distributed, damaged and fragmented. The terminal web was destroyed. Morphological alterations occurred early, after just 1 week of LFN-exposure, persisted with longer noise exposition and did not suffer any evolution. Changes were similar among all LFN-exposed groups.

Conclusions: LFN-exposed duodenal mucosa develops destruction of microvilli and terminal web, leading to cellular death and development of superficial erosions. These lesions of cytoskeleton structures could explain why cells with actinic and tubulinic structures like cilia and microvilli present severe destruction after LFN-exposure. These erosions are similar to those seen in dyspeptic patients.