[31P]/[1H] nuclear magnetic resonance study of mitigating effects of GYKI 52466 on kainate-induced metabolic impairment in perfused rat cerebrocortical slices.
OBJECTIVE
Kainic acid (KA) has long been used in experimental animals to induce status epilepticus (SE). A mechanistic implication of this is the association between excitotoxicity and brain damage during or after SE. We evaluated KA-induced metabolic impairment and the potential mitigating effects of GYKI 52466 [1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine] in superfused rat cerebral cortical slices.


METHODS
Interleaved [31P]/[1H] magnetic resonance spectroscopy (MRS) was used to assess energy metabolism, intracellular pH (pHi), N-acetyl-L-aspartate (NAA) level, and lactate (Lac) formation before, during, and after a 56-min exposure to 4 mM KA in freshly oxygenated artificial cerebrospinal fluid (oxy-ACSF).


RESULTS
In the absence of GYKI 52466 and during the KA exposure, NAA, PCr, and ATP levels were decreased to 91.1 +/- 0.8, 62.4 +/- 3.9, and 59.1 +/- 4.3% of the control, respectively; Lac was increased to 118.2 +/- 2.1 %, and pH, was reduced from 7.27 +/- 0.02 to 7.13 +/- 0.02. During 4-h recovery with KA-free ACSF, pHi rapidly and Lac gradually recovered, NAA decreased further to 85.5 +/- 0.3%, and PCr and ATP showed little recovery. Removal of Mg2+ from ACSF during KA exposure caused a more profound Lac increase (to 147.1 +/- 4.0%) during KA exposure and a further NAA decrease (to 80.4 +/- 0.5%) during reperfusion, but did not exacerbate PCr, ATP, and pHi changes. Inclusion of 100 microM GYKI 52466 during KA exposure significantly improved energy metabolism: the PCr and ATP levels were above 76.6 +/- 2.1 and 82.0 +/- 2.9% of the control, respectively, during KA exposure and recovered to 101.4 +/- 2.4 and 95.0 +/- 2.4%, respectively, during reperfusion. NAA level remained at 99.8 +/- 0.6% during exposure and decreased only slightly at a later stage of reperfusion.


CONCLUSIONS
Our finding supports the notion that KA-induced SE causes metabolic disturbance and neuronal injury mainly by overexcitation through non-N-methyl-D-aspartate (NMDA) receptor functions.
Tang
P
P
Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, Pennsylvania 15261, USA.
Liachenko
S
S
Melick
J A
JA
Xu
Y
Y
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D014151:Anti-Anxiety Agents; D000927:Anticonvulsants / Q000494:pharmacology*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001569:Benzodiazepines / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D002555:Cerebrospinal Fluid / Q000378:metabolism; D004734:Energy Metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007608:Kainic Acid; D007773:Lactates / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010759:Phosphorus Isotopes; D011522:Protons; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013226:Status Epilepticus / Q000139:chemically induced* / Q000175:diagnosis / Q000378:metabolism*
D014151:Anti-Anxiety Agents; D000927:Anticonvulsants; D018691:Excitatory Amino Acid Antagonists; D007773:Lactates; D018696:Neuroprotective Agents; D010759:Phosphorus Isotopes; D011522:Protons; D016194:Receptors, N-Methyl-D-Aspartate; C061950:GYKI 52466; D001569:Benzodiazepines; D001224:Aspartic Acid; D000255:Adenosine Triphosphate; C000179:N-acetylaspartate; D008274:Magnesium; D007608:Kainic Acid