Electrophysiological data showing the acute alcohol effect on intrinsic excitability in the murine posterior parietal cortex

Description

It is well established that alcohol interacts with multiple molecular targets, including ligand- and voltage-gated ion channels and intracellular signal proteins, leading to molecular and cellular neuroadaptations in various brain regions, including the cerebral cortex, hippocampus, amygdala, and cerebellum. Little is known about the effects of alcohol on the posterior parietal cortex (PPC), a cortical region involved in multiple cognitive and executive functions. To fill this important gap in the literature, we performed a series of ex vivo electrophysiological recordings in current-clamp mode to characterize the acute effects of alcohol (50 mM) and subsequent washout on pyramidal neurons and interneurons located in layers V-VI of PPC. Adult male and female mice (postnatal days 100-110) were sacrificed, and their brains were rapidly removed. Coronal brain slices (300 µM) containing PPC were cut using a Leica VT1000 Plus vibratome. After starting the whole-cell recording, stable current-clamp responses were observed for 15 minutes. We then recorded the baseline activity, applied 50 mM alcohol, and monitored the responses at 5-minute interval. Washout effects were characterized 10 minutes following alcohol application. Only recordings with a stable access resistance that varied < 25% and did not exceed 25 ΜΩ were included in the analysis. Cells recorded with capacitance values > 100 pF were considered pyramidal neurons, while cells showing values < 100 pA were analyzed as interneurons. Recordings were digitized at 5 kHz and filtered at 2 kHz using an analog-to-digital signal converter Model 1440A, and acquired using Clampex Software 10.7. Off-line analysis was performed using Clampfit 10.7 (Molecular Devices, Sunnyvale, CA). Resting membrane potential, input resistance, rheobase, action potential (AP) threshold, and firing frequency were assessed at baseline, after 10 minutes of bath application of alcohol and following a 10-minute washout period. Resting membrane potential was calculated by averaging the membrane voltage measured immediately before each current injection. Input resistance was calculated by measuring voltage responses to seven hyperpolarizing current injections (ranging from –300 pA to 0 pA) and applying Ohm’s law (V = IR), with the slope of the current–voltage relationship used to determine input resistance. Rheobase was defined as the lowest depolarizing current step that induced the first action potential. AP threshold was identified as the membrane potential at which the neuron began to fire. AP frequency was determined by averaging the firing rate during the last three depolarizing current steps (+200, +250, and +300 pA), which were selected to provide a representative measure of overall excitability during steady-state firing. The excel file included here is organized into several tabs (sheets) as follows: 1. Males Interneurons 2. Females Interneurons 3. Males Pyramidal Neurons 4. Females Pyramidal Neurons

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