Barbiturate anaesthesia reduces the neurotoxic effects of quinolinate but not ibotenate in the rat pedunculopontine tegmental nucleus.

We have previously demonstrated that ibotenate (IBO) injected into the pedunculopontine tegmental nucleus (PPTg) damages all neurones there while quinolinate (QUIN) makes relatively selective lesions of cholinergic neurones. We now compare the effects of two anaesthetics, sodium pentobarbitone and Avertin (tribromoethanol/tert-amylalcohol dissolved in ethanol, saline and phosphate buffer) on three doses of IBO and QUIN in the PPTg. Diaphorase-positive cell loss after QUIN was attenuated under barbiturate, the relative selectivity of QUIN for diaphorase-positive neurones was lost and lesion volumes were uniformly small compared with lesions made under Avertin anaesthesia. IBO toxicity was unaffected by anaesthesia. These data are discussed with reference to the actions of excitotoxins at glutamate receptor subtypes and interactions of barbiturates with the GABAA receptor.