Neuropathic Pain: The Paradox of Dynorphin

NMDA receptor agonists attenuate the specific binding of [³H]dynorphin A(2–17) to rat brain membranes. The specific binding of [³H]dynorphin A(2–17) was reduced by 30% in the collective presence of glutamate, glycine, and spermine.

^a Units are arbitrary. Crude membranes (300 μg) from rat brain were incubated (5 mM Tris buffer, pH 7.5) with 1 nM [³H]dynorphin A(2–17) with or without agonists (10 μM glutamate, 10 μM glycine, and 10 μM spermidine) in a final volume of 0.5 mL for 2 h at 25°C. Non-specific binding was defined as the binding of the radiolabeled ligand in the presence of unlabeled 200 μM dynorphin A(2–17).