Effects of barbital and lorazepam in the AT and ANT rats: motor performance and brain monoamine functions.

The motor impairing effects and central monoaminergic neuronal effects of barbital (120 mg/kg, IP) and lorazepam (3 mg/kg, IP) were studied in the alcohol tolerant (AT) and alcohol non-tolerant (ANT) rat lines developed for low and high sensitivity to motor impairment from ethanol (2 g/kg, IP), respectively. Like ethanol, both barbital and lorazepam impaired the performance of the ANT rats more than that of the AT rats. Ethanol increased the synthesis of catecholamines in the striatum and hypothalamus, but barbital and also lorazepam decreased it in both rat lines. Ethanol increased or did not modify the synthesis of 5-HT in the cerebral cortex and hypothalamus, while barbital and lorazepam decreased it; the rat lines did not differ in these neuronal effects.