Effects of ketamine on the in vivo toxicity of quinolinate and N-methyl-D-aspartate in the rat hippocampus.

Systemic injections of ketamine (30 mg/kg, i.p.) decreased the neurotoxicity of the NMDA agonists NMDA (N-methyl-D-aspartic acid) and quinolinic acid injected into the hippocampus of the rat, although such protection was incomplete. Simultaneous injections of ketamine into the hippocampus decreased rather than increased these protective effects. In contrast, almost complete protection was provided by intra-hippocampal injections of DL-2-amino-5-phosphonovaleric acid (DL-APV). The duration of anaesthesia was not responsible for the protective effects of systemic ketamine, as the intracerebral injections of the NMDA agonists produced similar neuronal lesions under both halothane or nembutal anaesthesia.