Effects of ethanol on sensory stimulus-evoked responses in the cerebellar molecular layer in vivo in mice

• Sensory stimulation (SS) evokes field potential responses in the cerebellar molecular layer via mossy fiber pathway.
• Ethanol enhances the GABAergic components of the SS evoked response at low concentration.
• High concentration of ethanol decrease the GABAergic components of the SS evoked response.
• Ethanol modulates GABAA receptors or GABA release in cerebellar molecular layer.

Overdose intake of ethanol can impair cerebellar cortical neurons to integrate and transfer external information, resulting in a dysfunction of cerebellar motor regulation or cerebellar ataxia. However, the mechanisms underlying ethanol-impaired transfer of sensory information from cerebellar cortical molecular layer neurons remain unclear. In the present study, we investigated the effects of ethanol on sensory stimulation-evoked responses in the cerebellar molecular layer of urethane-anesthetized mice, by electrophysiological and pharmacological methods. Our results demonstrated that air-puff stimulation (30 ms, 50–60 psi) of the ipsilateral whisker-pad evoked field potential responses in the molecular layer of the cerebellar cortex folium Crus II, which expressed a negative component (N1) followed by a gamma-aminobutyric acid receptor A (GABAA)-mediated positive component (P1). Cerebellar surface perfusion of ethanol between 2 and 5 mM did not change the latency of the evoked responses and the amplitude of N1, but enhanced the amplitude and the area under the curve of P1. Interestingly, high concentrations (>20 mM) of ethanol induced a significantly decrease in the amplitude and area under the curve of P1. Furthermore, high concentration ethanol (300 mM) significantly decreased the rise in tau and tau decay value of P1, whereas low concentration ethanol (2–5 mM) significantly increased these values of P1. Inhibition of GABAA receptor activity reversed P1 and also abolished the effects of ethanol on sensory stimulation-evoked responses. These results indicated that ethanol induced a bidirectional effect on the sensory stimulation-evoked GABAergic responses in the cerebellar cortical molecular layer, suggesting that acute alcohol intake impacted the sensory information processing of cerebellar cortex.