Increased hippocampal GABAergic inhibition after long-term high-intensity sound exposure

Abstract

Exposure to loud sounds has been related to deleterious mental and systemic effects in addition to auditory maladies. Hippocampal function has been shown to be affected to either high intensity sound exposure or long-term sound deprivation. Hippocampal long-term potentiation (LTP) is inhibited after 10 days of daily exposure to 2 minutes of high-intensity noise (110 dB), in the hippocampi of Wistar rats. He we investigate how the glutamatergic and GABAergic neurotransmission mediated by ionotropic receptors is affected by the same protocol of high intensity sound exposure. We found that while the glutamatergic transmission both by AMPA/kainite and NMDA receptors in the Schaffer-CA1 synapses is largely unaffected by long-term exposure to high intensity sound, the amplitude of the inhibitory GABAergic currents is potentiated, but not the frequency of the both spontaneous and miniature currents. We conclude that GABAergic transmission is potentiated at the post-synaptic level in the hippocampal CA1 pyramidal neurons after a prolonged exposure to short periods of high-intensity sound. This effect could be an important factor for the reduced LTP in the hippocampi of these animals after high intensity sound exposure, and demonstrated that prolonged exposure to high- intensity sound can affect hippocampal inhibitory transmission and consequently its function.