Ethanol affects striatal interneurons directly and projection neurons through a reduction in cholinergic tone

Craig Peter Blomeley (1) , Sarah Cains (1) , Richard J.H. Smith (1) , Enrico Bracci (1)

1 Life Sciences

The acute effects of ethanol on the neurons of the striatum, a basal ganglia nucleus crucially involved in motor control and action selection, were investigated using whole-cell recordings. An intoxicating concentration of ethanol (50 mM) produced inhibitory effects on striatal large aspiny cholinergic interneurons (LAIs) and low-threshold spike interneurons (LTSIs). These effects persisted in the presence of tetrodotoxin and were due to an increase in potassium currents, including those responsible for medium and slow afterhyperpolarizations. In contrast, fast-spiking interneurons (FSIs) were directly excited by ethanol, which depolarised these neurons through the suppression of potassium currents. Medium spiny neurons (MSNs) became hyperpolarized in the presence of ethanol, but this effect did not persist in the presence of tetrodotoxin and was mimicked and occluded by application of the M1 muscarinic receptor antagonist telenzepine. Ethanol effects on MSNs were also abolished by 100 µM barium. This showed that the hyperpolarisations observed in MSNs were due to decreased tonic activation of M1 muscarinic receptors, resulting in an increase in Kir2 conductances. Evoked GABAergic responses of MSNs were reversibly decreased by ethanol with no change in paired-pulse ratio. Furthermore, ethanol impaired the ability of thalamostriatal inputs to inhibit a subsequent corticostriatal glutamatergic response in MSNs. These results offer the first comprehensive description of the highly cell-type specific effects of ethanol on striatal neurons and provide a cellular basis for the interpretation of ethanol influence on a brain area crucially involved in the motor and decisional impairment caused by this drug.

Mots clés: GABA; Glutamate; Acetylcholine; Neuropharmacology; striatum; ethanol; basal ganglia; cholinergic interneuron; fast spiking interneuron

Craig Peter Blomeley, Sarah Cains, Richard J.H. Smith, Enrico Bracci. Ethanol affects striatal interneurons directly and projection neurons through a reduction in cholinergic tone. Neuropsychopharmacology, 2011, ⟨10.1038/npp.2010.241⟩. ⟨hal-00612960⟩