MK-801 does not prevent development of ischemic tolerance in rat brain

Tolerance against ischemia can be induced in the CA1 region of the hippocampus of the brain. In gerbils tolerance evolvement is blocked by the NMDA-antagonist MK-801. To examine this mechanism in rats, MK-801 was administered i.p. 1 h prior to tolerance inducing ischemia. Body temperature and activity were monitored before and after ischemia, and show that MK-801 results in hyperthermia immediately after the injection, the post-ischemic body temperature remain elevated until 5 h post-ischemia in spite of the animals being less active than control animals. Histology shows that pre-treatment with MK-801 does not affect the CA1 neuronal density, and we thus conclude that for the used rat model, MK-801 does not affect development of ischemic tolerance.