Are the effects of toluene on the vestibulo and opto-ocular motor system inhibited by the action of GABAB antagonist CGP 35348?

The acute effects of toluene and a selective GABAB-antagonist, CGP 35348, on the vestibulo and opto-ocular motor (VOOM) system in rats were investigated by recording of compensatory eye-movements during vestibular and optokinetic stimulations. It has previously been demonstrated that toluene enhances the performance of the basic vestibulo-oculomotor reflex (VOR) and depresses the effects of the visual input to this reflex. It has been proposed that these effects are caused by alterations of the GABA-transmission system in the cerebellum. It has now been demonstrated that the exaggerating effects of toluene on the VOR, tested by angular horizontal acceleration/deceleration of the animals in darkness, are inhibited by CGP 35348 in a dose related way. On the contrary, the depressing effects on the visual input, tested by optokinetic stimulation, by angular acceleration/deceleration with a simultaneous conflicting visual stimulation and by eliciting saccades, could not be prevented by CGP 35348. The results support the hypothesis that toluene causes some of the effects on the VOOM system by influence on the GABA-transmission. The findings are in agreement with a recent report of increased levels of extracellular GABA in the cerebellar cortex during exposure to toluene.