Low-frequency noise effects on the rat parotid gland: A transmission electron microscopy study

Introduction: Low-frequency noise (LFN) is a ubiquitous physical stressor known to cause degenerative cellular changes and organ alterations with functional repercussions both in humans and animals. Materials and methods: After acceptance of the study protocol by a local ethics committee, 20 Wistar rats were randomly divided into two equal groups. One group was kept in silence and the other continuously exposed to LFN during 13 weeks. The rats had unlimited access to water and were fed standard rat chow. After exposure, the animals were sacrificed and the parotid glands were excised and prepared for transmission electron microscopy. Results: The acinar cells showed marked ultrastructural alterations, such as intracellular vacuolization, loss of cell polarity, increased heterochromatin, cytoplasmic inclusions, and oncocytic transformation. Conclusions: LFN induces ultrastructural changes in the rat parotid gland that correlate with previously described functional changes.