Impulse noise transiently increased the permeability of nerve and glial cell membranes, an effect accentuated by a recent brain injury.
A single exposure to intense impulse noise may cause diffuse brain injury, revealed by increased expression of immediate early gene products, transiently altered distribution of neurofilaments, accumulation of beta-amyloid precursor protein, apoptosis, and gliosis. Neither hemorrage nor any gross structural damage are seen. The present study focused on whether impulse noise exposure increased the permeability of nerve and glial cell membranes to proteins. Also, we investigated whether a preceding, minor focal surgical brain lesion accentuated the leakage of cytosolic proteins. Anaesthetized rats were exposed to a single impulse noise at either 199 or 202 dB for 2 milliseconds. Transiently elevated levels of the cellular protein neuron specific enolase (NSE) and the glial cytoplasmic protein S-100 were recorded in the cerebrospinal fluid (CSF) during the first hours after the exposure to 202 dB. A surgical brain injury, induced the day before the exposure to the impulse noise, was associated with significantly increased concentrations of both markers in the CSF. It is concluded that intense impulse noise damages both nerve and glial cells, an effect aggravated by a preexisting surgical lesion. The impulse of the shock wave, i.e. the pressure integrated over time, is likely to be the injurious mechanism. The abnormal membrane permeability and the associated cytoskeletal changes may initiate events, which eventually result in a progressive diffuse brain injury.
Säljö
Annette
A
Institute of Anatomy and Cell Biology, University of Göteborg, Göteborg, Sweden.
Huang
Ying-Lai
YL
Hansson
Hans-Arne
HA
D000818:Animals; D001930:Brain Injuries / Q000134:cerebrospinal fluid* / Q000503:physiopathology; D002463:Cell Membrane Permeability; D008297:Male; D009457:Neuroglia / Q000473:pathology*; D009474:Neurons / Q000473:pathology*; D009622:Noise / Q000009:adverse effects*; D010751:Phosphopyruvate Hydratase / Q000134:cerebrospinal fluid; D051381:Rats; D017207:Rats, Sprague-Dawley; D009418:S100 Proteins / Q000134:cerebrospinal fluid
D009418:S100 Proteins; D010751:Phosphopyruvate Hydratase