Behavioral effects of the selective blockade of metabotropic glutamate receptor subtype 5 in experimental hypoxia.

The behavioral activity of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective antagonist of metabotropic glutamate receptor subtype 5 (mGluR5), was assesed in control groups of rats and in rats that underwent short-term hypoxia. MPEP applied intravenously (iv) at the dose of 1 mg/kg was tested using the open field test, the passive avoidance test and the elevated "plus" maze test. MPEP significantly increased the number of crossings, rearings and bar approaches in the open field test. It improved the consolidation and retrieval in the passive avoidance situation and did not produce any significant effects in control rats in the elevated "plus" maze test. Hypoxia (2% O2, 98% N2) significantly inhibited locomotor and exploratory activity of rats and also impaired consolidation and retrieval processes, but it did not evoke any changes in the elevated "plus" maze test. MPEP in hypoxia-exposed groups of rats inhibited locomotor and exploratory activity in comparison with MPEP-treated control group. Hypoxia significantly diminished beneficial effect of MPEP on consolidation. In spite of experimental conditions of hypoxia, the effect of MPEP on retrieval was preserved. MPEP used before hypoxia did not significantly influence all parameters of the elevated "plus" maze test. In conclusion, MPEP had beneficial effect on retrieval in hypoxia.