Dimaprit--induced neurotoxicity.

The neurotoxicity of the histamine H2 agonist dimaprit was characterized. Dimaprit (100 micrograms administered into the lateral cerebral ventricle) induced a large area of brain necrosis 1-3 days later which was uniformly lethal. Lower doses caused dose - related effects on survival, gross brain pathology and body weight. Experiments with other H2 agonists and H2 antagonists, together with studies by others demonstrating a similar toxicity of the congener homodimaprit suggest that the neurotoxicity of dimaprit is independent of brain H2 receptors. Although dimaprit is a useful tool for the characterization of H2 receptor responses, the present results show that this agent must be used with caution, if at all, in classifying brain H2-receptor mediated events.