The present study examined potential neuroprotective effects of HU-211, a synthetic non-psychotropic cannabinoid with non-competitive NMDA antagonist properties on neurones exposed to various excitotoxins in culture. HU-211 was found to protect neurones from NMDA and quisqualate-induced toxicity but not that produced by AMPA or kainate. NMDA-mediated neurotoxicity was blocked by HU-211 in a dose dependent manner with an EC50 = 3.8 +/- 0.9 microM. Radioligand binding studies have shown that HU-211 inhibits the binding of [3H]MK-801 to rat forebrain membranes (KI = 11.0 microM +/- 1.323) in a competitive manner, but was unable to displace [3H]kainate and [3H]AMPA binding. These data suggest that the neuroprotective activity of HU-211 is directly associated with the NMDA receptor channel and possibly with the quisqualate receptor of the metabotropic class. Thus, HU-211 appears to act as an NMDA open channel blocker and shows promise as a novel neuroprotectant for clinical use.
Amino Acids Animals