Correlation of 3-mercaptopropionic acid induced seizures and changes in striatal neurotransmitters monitored by microdialysis.
OBJECTIVE
The goal of this study was to use a status epilepticus steady-state chemical model in rats using the convulsant, 3-mercaptopropionic acid (3-MPA), and to compare the changes in striatal neurotransmission on a slow (5min) and fast (60s) timescale. In vivo microdialysis was combined with electrophysiological methods in order to provide a complete evaluation of the dynamics of the results obtained.


OBJECTIVE
To compare the effects of a steady-state chemical model pof status epilepticus on striatal amino-acid and amine neurotransmitters contents, as measured via in vivo microdialysis combined with electrophysiological methods. Measurements were performed on samples collected every 60s and every 5min. "Fast" (60s) and "slow" (5min) sampling timescales were selected, to gain more insight into the dynamics of GABA synthesis inhibition and of its effects on other neurotransmitters and on cortical electrical activity.


METHODS
3-MPA was administered in the form of an intra-venous load (60mg/kg) followed by a constant infusion (50mg/kg/min) for min. Microdialysis samples were collected from the striatum at intervals of 5min and 60s and analyzed for biogenic amine and amino acid neurotransmitters. ECoG activity was monitored via screws placed over the cortex.


RESULTS
In the 5min samples, glutamate (Glu) increased and γ-aminobutyric acid (GABA) decreased monotonically while changes in dopamine (DA) concentration were bimodal. In the sixty second samples, Glu changes were bimodal, a feature that was not apparent with the 5min samples. ECoG activity was indicative of status epilepticus.


CONCLUSIONS
This study describes the combination of in vivo microdialysis with electrophysiology to monitor the effect of 3-MPA on neurotransmission in the brain. This led to a better understanding of the chemical changes in the striatum due to the applied 3-MPA chemical model of status epilepticus.
R.N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, United States.
Eric W
EW
Crick
Comprehensive Epilepsy Center, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, United States; Flint Hills Scientific, LLC, 5040 Bob Billings Parkway, Suite A, Lawrence, KS 66049, United States.
Ivan
I
Osorio
Flint Hills Scientific, LLC, 5040 Bob Billings Parkway, Suite A, Lawrence, KS 66049, United States.
Mark
M
Frei
R.N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, United States.
Andrew P
AP
Mayer
R.N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, United States. Electronic address: clunte@ku.edu.
Craig E
CE
Lunte
D015097:3-Mercaptopropionic Acid; D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism*; D001679:Biogenic Amines / Q000378:metabolism*; D058256:Brain Waves; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism; D004569:Electroencephalography; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D017208:Rats, Wistar; D013226:Status Epilepticus / Q000139:chemically induced* / Q000378:metabolism* / Q000503:physiopathology; D009435:Synaptic Transmission; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D001679:Biogenic Amines; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D015097:3-Mercaptopropionic Acid; D004298:Dopamine
3-Mercaptopropionic acid; Catecholamines; Microdialysis sampling; Neurotransmitter amino acids; Status epilepticus steady-state chemical model