Neuronal function spontaneously recovers in organotypic hippocampal slice cultures after repetitive exposure to occupational-level shock waves

Abstract

Blast-induced traumatic brain injury has long been a prevalent health issue. There is growing concern for repeated exposures to low-level blasts with studies suggesting effects on neurological impairments and long-term health problems. The purpose of this study was to expand our understanding of the neurophysiological consequences of repetitive mild blast from a range of occupational exposure levels. We studied shock waves of peak overpressures ranging from 45 to 270 kPa and impulses of 54 to 295 kPa\(\cdot \)ms. We observed the effects of these shock waves in organotypic hippocampal slice cultures generated from neonatal rat pups. This model allowed us to isolate the effects of blast on neuronal function without the confounding factors of scaling and peripheral systemic input. We found that blast severity and inter-blast interval were both integral in understanding non-injurious limits for blast exposure. With higher blast severity, the inter-blast interval needed to be extended to avoid deficits in long-term potentiation (LTP), a form of synaptic plasticity. Furthermore, blast exposures too close in time synergistically affected LTP negatively, producing a dose response with more exposures leading to greater deficits in LTP. Overall, even the lowest blast tested was capable of producing functional deficits under the appropriate conditions. These findings can aid in the improvement of safety and training protocols to set occupational exposure limits to avoid neurological impairments and negative long-term health effects.