TUESDAY, Dec. 11 (HealthDay News) -- A novel antidepressant compound, a glycine site functional partial agonist, GLYX-13, works by modulating NR2B-containing N-methyl-D-aspartate (NMDA) receptors (NMDARs) in the brain, according to a study presented at the annual meeting of the American College of Neuropsychopharmacology, held from Dec. 2 to 6 in Hollywood, Fla.
Joseph Moskal, Ph.D., from the Falk Center for Molecular Therapeutics in Evanston, Ill., and colleagues examined the in vitro effects of GLYX-13, including the functional agonist and antagonist effects.
The researchers found that, based on [3H]MK-801 potentiation assays, GLYX-13 exhibited partial agonist activity at the glycine site (half maximal effective concentration [EC50], 64 nM; 26.1 percent activity relative to glycine). Similar potencies to the NMDAR were measured in the presence of a full agonist, in [3H]MK-801 assays, and by direct NMDAR current measured from CA1 pyramidal neurons in rat hippocampal slices. GLYX-13 did not affect the affinity or rate of [3H]glycine binding in purified rat cortical membranes. GLYX-13 was ineffective when competing with the high affinity glycine site agonist [3H]L-689,560. The effect of GLYX-13 was antagonized by the NR2B-specific inhibitor Ro 25-6981, in a dose-dependent manner. GLYX-13 was inactive at the glutamate and polyamine sites of the NMDAR. Using a doxycycline inducible HEK cell line expressing the functional human NR1/NR2B receptor subtype, the [3H]MK-801 results were corroborated, with partial agonist activity of GLYX-13 seen at the glycine site (EC50: 52 nM; 43.8 percent activity relative to glycine) and no activity at the glutamate site.
"Our study showed that this compound is capable of eliciting a robust and rapid antidepressant effect without the typical side effects seen with other drugs that also modulate the NMDA receptor," Moskal said in a statement.
The lead author is the founder of Naurex Inc., which conducted the clinical study.
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