• P K Nayak, H Zhang, and D S Kerr.
• Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand.
• Neuroscience. 2013 Mar 1;232:139-50.

AbstractPreviously we showed that 1-(4'-aminophenyl)-4-methyl-7,8-methylene-dioxy-2,3-benzodiazepine (GYKI-52466), an ionotropic AMPA receptor antagonist, can trigger strong, presumably metabotropic, protection against seizures and stroke at very low doses. To date, no study has determined brain and plasma concentrations of GYKI-52466 following subcutaneous administration in animals with or without brain damage. Here we developed and validated a rapid method of high-performance liquid chromatography with diode array detection. Chromatographic separation was achieved by a Luna C18 column using a mixture of 25 mM phosphate buffer (pH 7.0)-methanol-acetonitrile (40:37.5:22.5, v/v/v) as the mobile phase at a flow rate of 1.2 mL/min. The method showed acceptable precision and accuracy and allowed a precise quantification of 25 ng/mL GYKI-52466 in the plasma and brain. Recovery of GYKI-52466 from the plasma and brain was >87%, and GYKI was stable at room temperature and during prolonged storage at -20 °C. The method was successfully applied in measuring levels of GYKI-52466 following administration of 3 and 20 mg/kg of GYKI-52466 in control and brain damaged rats. A low brain concentration of 0.56 μM GYKI-52466 was observed with 3mg/kg compared to 10.7 μM with 20 mg/kg at 90 min post drug administration. Severe ataxia was observed with the 20mg/kg dose for up to 90 min. Furthermore, in ischaemic animals, there was no evidence of a 'surge' in brain GYKI concentrations at the injury site, confirming the integrity of the blood-brain barrier in the region of infarct. Taken together, our findings support a metabotropic mode of action underlying the low-dose neuroprotective efficacy of GYKI-52466.Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

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