The antinarcoleptic drug modafinil increases glutamate release in thalamic areas and hippocampus

THE antinarcoleptic drug modafinil [(diphenyl-methyl)sulfinyl-2- acetamide; Modiodal] dose-dependently inhibits the activity of GABA neurons in the cerebra cortex and in the nucleus accumbens, as well as in sleep- related brain areas such as the medial preoptic area and the posterior hypothalamus. This study examined the effects of modafinil (30-300 mg/kg, i.p.) on dialysate glutamate and GABA levels in the ventromedial (VMT) and ventrolateral (VLT) thalamus and hippocampal formation (Hip) of the awake rat. The results show a maximal increase in glutamate release in these brain regions at the 100 mg/kg dose, associated with a lack of effect on GABA release. Thus modafinil may increase excitatory glutamatergic transmission in these regions, altering the balance between glutamate and GABA transmission.