Quantitative autoradiography of L-[3H]glutamate binding to rat brain.

A technique has been developed to investigate sodium-independent L-[3H]glutamate binding in rat brain sections using quantitative autoradiography and tritium-sensitive film. Binding is rapid (reaching equilibrium in 5 min) and reversible (having a t 1/2 of dissociation of 0.38 min). Glutamate apparently bound to a single population of sites with a Kd of about 1.0 microM. The pharmacology of this binding site is similar to that observed in homogenate studies. There is marked regional variation in the amount of glutamate bound. Of the areas analyzed in detail, the density of sites is greatest in stratum moleculare of hippocampus, followed by striatum and cortex.