Ethanol and acetaldehyde: in vivo quantitation and effects on cholinergic function in rat brain.

First, ethanol (EtOH) and acetaldehyde levels were determined simultaneously in the striatum of free-moving rats after administration of their major oxidative enzyme inhibitors followed by EtOH. The results showed that acetaldehyde was present in the cyanamide (CY) + EtOH, CY + 4-methylpyrazole (4-MP) + EtOH and CY + sodium azide + EtOH groups. The CY + EtOH-induced peak acetaldehyde level was 195.2 +/- 19.4 microM, and this value was significantly higher than those in the other groups. The peak EtOH level was 25.9 +/- 2.3mM in the CY + 4-MP + EtOH group, and this level was considerably higher than the value in EtOH. No significant difference in brain EtOH levels was found in any of the other groups studied. Second, the effects of EtOH and acetaldehyde on choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) were investigated in the frontal cortex and hippocampus of high acetaldehyde-producing rats using RT-PCR and Western blot. The results showed that EtOH and acetaldehyde decreased ChAT expression at 40 and 240 min after EtOH dosing in the brain. The acetaldehyde-induced reduction in ChAT expression was significantly higher than that induced by EtOH. No remarkable alteration of AChE expression was observed. The study suggested that catalase made a significant contribution to acetaldehyde formation in the rat brain, and that EtOH and acetaldehyde decreased ChAT expression at 40 and 240 min after EtOH dosing.