Fig. 4.

Effects of CX546 on AMPA receptors in different brain regions. A, effect of CX546 on [³H]FW binding to membranes from eight brain regions of adult rats (3–5 months). Binding was measured at room temperature by using a centrifugation assay. [³H]FW was kept constant at 20 nM, and the concentration of CX546 was varied between 0 and 6 mM. The data are averages from three separate experiments with two membrane preparations. Binding for each region was normalized to that in the absence of CX546. The percentage values from three experiments were then averaged and are presented as mean and S.E.M. The E_max and EC₅₀ values and binding densities are summarized in Table 2. B, comparison of the same eight brain regions from rat pups (PND14). C, drug effect on receptors from adult hippocampus and thalamus before and after solubilization with 5% Triton X-100 (30 min at 4°C; insoluble material removed by centrifugation). Binding to solubilized receptors was measured by a filtration assay and is the average of two separate preparations of hippocampus and thalamus. E_max and EC₅₀ values are given in the text. Solubilization reduced the disparity in E_max between the brain regions and generally lowered the EC₅₀.