Effect of MPEP on rat's behavioral activity in experimental episodes of hypoxia.

PURPOSE The influence of the selective antagonism of metabotropic glutamate receptor subtype 5 (mGluR5) by MPEP (2-methyl-6-(phenylethynyl)-pyridine) on some behaviors was tested in control groups of rats and in rats exposed to short-term hypoxia once or to repeated episodes of hypoxia. MATERIAL AND METHODS We used the following methods: the open field test, the passive avoidance test and the object recognition test. Experimental hypoxia was produced by placing rats in a glass chamber flushed with a mixture of 2% O2 in N2. RESULTS MPEP applied intravenously (IV) at the dose of 1 mg kg-1 significantly enhanced locomotor and exploratory activity, impaired acquisition, but improved consolidation and retrieval in the passive avoidance situation and did not alter rats' activity in the object recognition test. The single short-term hypoxia significantly inhibited motility of rats and profoundly impaired acquisition, consolidation and retrieval processes, but the positive effect of MPEP on retrieval was preserved. Hypoxia also did not influence the activity of rats in the object recognition object. The repeated episodes of short-term hypoxia were induced for five consecutive days and it also inhibited motility of rats, but did not change consolidation and retrieval processes. The episodes of hypoxia significantly diminished the beneficial effect of MPEP on consolidation and retrieval, and also the enhancement of locomotor and exploratory activity. MPEP, used in rats subjected to the single or the repeated episodes of short-term hypoxia, did not change recognition memory. CONCLUSION MPEP used before the single episode of hypoxia only, had beneficial effect on retrieval.