PB2-AFFINITY SITES - DEVELOPMENTAL AND REGIONAL BRAIN EXPRESSION( INHIBITS NMDA RECEPTOR FUNCTION AT HIGH AND LOW)

Lead (Pb2+) is a potent inhibitor of the NMDA receptor complex. In the present study we have measured high and low affinity components of NM DA receptor inhibition by Pb2+ using [H-3]-MK-801 binding as a biochem ical indicator of NMDA receptor function. The inhibitory effects of Pb 2+ were dependent on the age of the rat and the brain region analyzed. The number of [H-3]-MK-801 binding sites associated with the high and low affinity sites of Pb2+ inhibition in the hippocampus increased as a function of age, peaking at postnatal day 28 and 21, respectively. In the cerebellum, a steady decrease in the number of both types of Pb 2+-sensitive [H-3]-MK-801 binding sites was measured from postnatal da y 1 to adulthood High and low affinity Pb2+-sensitive [H-3]-MK-801 bin ding sites were measured in the cerebral cortex in early development, but the resolution of the two sites was not possible after postnatal d ay 14. The Pb2+ sensitivity of the NMDA receptor complex also appeared to be regulated developmentally. (C) 1997 Inter Press, Inc.