Effect of amphetamine on the expression of the metabotropic glutamate receptor 5 mRNA in developing rat brain

Mechanisms underlying the acute effects of amphetamine (AMP) were examined by monitoring the expression of metabotropic glutamate receptor 5 (mGluR5) and specific H-3-glutamate binding in the developing rat brain. Each of the postnatal day (P) 4, P21 and P60 rats received one intraperitoneal injecti on of AMP, 5 mg/kg or saline and were sacrificed one hour later. In situ hy bridization analysis revealed that the AMP treatment raised the levels of t he mGluR5 mRNA by 9-28% in the neurons of the layer 5 of motor and somatose nsory cortices, whereas reduced the levels by 12-28% in the layer 5 of peri rhinal cortex and the ventromedial part of caudate-putamen of the 3 ages. I n the layer 2/3 neurons of cingular cortex, an 18% higher and 14% and 22% l ower than control levels of the mRNA were detected in the P4 and in the P21 and P60 rats injected with AMP. Moreover, the levels of mGluR5 mRNA in the hippocampi and dentate gyri were elevated by AMP to 110-151% of controls i n the rats of 3 ages. Reversible 3H-glutamate binding assay showed an incre ase of 25% and a 12% decrease in the binding levels in the cortices of AMP- treated P4 and P21 rats. The AMP administration also produced a 27% reducti on and 62% elevation in the binding of the hippocampi of P4 and P60 rats. T he results reveal age- and region-dependent changes in the expression of th e glutamate receptors induced by AMP and may indicate differential plastic capability of the neurons to the drug perturbation.