Microdialysis for the determination of acetaldehyde and ethanol concentrations in the striatum of freely moving rats

Abstract

The subject of the present paper is the simultaneous determination of ethanol (EtOH) and acetaldehyde (AcH) concentrations in the striatum of freely moving rats using an in vivo microdialysis followed by head-space gas chromatography (GC). Major operation conditions of GC were as follows: column, injector and detector temperatures 90, 110 and 200 °C, respectively; Supelcowax™ wide bore capillary column (60 m length, 0.53 mm i.d., 2 μm film thickness); carrier gas, nitrogen; flow rate, 20 ml/min. The recovery of EtOH and AcH at a concentration 40 mM and 250 μM, respectively, by microdialysis showed a maximum of 83.8±12.2 and 51.2±6.5%, respectively, at a flow rate of 0.8 μl/min. A good linear calibration curve in the concentration range of 5–50 mM for EtOH ( r=0.998), and 10–250 μM for AcH ( r=0.988) was observed. Microdialysates were collected for 10 min each after insertion of probe into the striatum. Rats were treated with cyanamide (100 mg/kg, a potent aldehyde dehydrogenase inhibitor) and 60 min later with EtOH (1 g/kg) intraperitoneally. A 10 min sample was about 8 μl. This volume was mixed with 40 μl of 0.002% t-butanol as an internal standard in 0.6N perchloric acid, and then analyzed by head-space GC method. The peak EtOH and AcH concentrations in the striatal dialysates reached maximum at 30 min, and then gradually decreased. This method represents a reasonable tool to quantify in vivo both AcH and EtOH levels simultaneously in rat brain.