THE N-METHYL-D-ASPARTATE RECEPTOR PATHWAY IS INVOLVED IN HYPOXIA-INDUCED C-FOS PROTEIN EXPRESSION IN THE RAT NUCLEUS OF THE SOLITARY TRACT

Immediate early genes, like c-fos, are believed to be involved in trig gering the expression of other genes such as those involved in the syn thesis of neurochemicals. Exposure of unanesthetized rats to oxygen de privation induces activation of the c-fos gene within the nucleus trac tus solitarius, resulting in expression of fos-like immunoreactive pro tein (Fos). Prior administration of MK-801, a nonselective antagonist of the N-methyl-D-aspartate (NMDA)-sensitive glutamate receptor (1 or 2 mg/kg), significantly attenuated but did not completely block hypoxi a-induced Fos expression. However, blockade of muscarinic receptors by atropine sulfate (2, 10 or 25 mg/kg) had no measurable effects on Fos expression induced by oxygen deprivation. These results suggest that an NMDA receptor signalling pathway is partly involved in programming the expression of early response genes that regulate various aspects o f the response to oxygen deprivation.