Ethanol sensitivity of postsynaptic receptors in the abdominal ganglion of Aplysia californica.

We examined the effects of ethanol on post-synaptic receptors in the abdominal ganglion of Aplysia californica, including those sensitive to acetylcholine (ACh) and gamma-aminobutyric acid (GABA). Current elicited by direct application of acetylcholine to the cell body was composed of two components; a fast component (peak current - ca. 800 ms) and a slower component (peak current - ca. 12.2 s). These two components were differentially sensitive to ethanol. The fast component, which represents a chloride conductance, was significantly reduced in ethanol concentrations as low as 50 mM, while the slow component of the response, carried by potassium ions, was unaffected by ethanol at to ethanol, showing no change in 50 mM ethanol, and a slight, but statistically significant reduction of the response to GABA in 100 mM ethanol. These results suggest that the cholinergic system warrants further study, since the receptors gating the fast response consistently show sensitivity in the clinically-relevant range. In addition, results obtained studying these receptors may bear on the question of ethanol's site of action, since the receptor-channel complexes associated with the fast and slow responses are differentially sensitive to ethanol, although they are found in the same cell, and therefore would share the same bulk lipid matrix.