Coactivation of GABA(A) and GABA(B) receptor results in neuroprotection during in vitro ischemia.
OBJECTIVE
The possible neuroprotective effect of endogenous gamma-aminobutyric acid (GABA) on the irreversible electrophysiological changes induced by in vitro ischemia on striatal neurons was investigated. In particular, the aim of the study was the characterization of the neuroprotective action of 2 antiepileptic drugs increasing GABAergic transmission such as tiagabine, a GABA transporter inhibitor, and vigabatrin, an irreversible inhibitor of GABA transaminase.


METHODS
Extracellular field potential recordings were obtained from rat corticostriatal slice preparations. In vitro ischemia was delivered by switching to an artificial cerebrospinal fluid solution in which glucose was omitted and oxygen was replaced with N(2).


RESULTS
An irreversible loss of the field potentials recorded from striatal neurons was observed after 10 minutes of ischemia in control solution. Conversely, tiagabine and vigabatrin partially prevented the ischemia-induced field potential loss. Surprisingly, both GABA(A) and GABA(B) receptor antagonists blocked these effects. Accordingly, neuroprotection could be obtained only when GABA(A) and GABA(B) receptor agonists were coapplied, but not when a single agonist was given in isolation.


CONCLUSIONS
Antiepileptic drugs targeting GABAergic transmission can exert neuroprotective effects against ischemia by increasing endogenous GABA levels and via the activation of both GABA(A) and GABA(B) receptors.
Costa
Cinzia
C
Clinica Neurologica, Dipartimento di Neuroscienze, Università di Tor Vergata, Rome, Italy.
Leone
Giorgia
G
Saulle
Emilia
E
Pisani
Francesco
F
Bernardi
Giorgio
G
Calabresi
Paolo
P
D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D002545:Brain Ischemia / Q000188:drug therapy* / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004558:Electric Stimulation; D018755:GABA Agonists / Q000494:pharmacology; D050485:GABA Plasma Membrane Transport Proteins; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000037:antagonists & inhibitors; D026901:Membrane Transport Proteins; D018696:Neuroprotective Agents / Q000494:pharmacology*; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology; D009557:Nipecotic Acids / Q000494:pharmacology; D027361:Organic Anion Transporters; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D000078308:Tiagabine; D020888:Vigabatrin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000927:Anticonvulsants; D002352:Carrier Proteins; D018755:GABA Agonists; D050485:GABA Plasma Membrane Transport Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D018696:Neuroprotective Agents; D014179:Neurotransmitter Uptake Inhibitors; D009557:Nipecotic Acids; D027361:Organic Anion Transporters; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; D020888:Vigabatrin; D000078308:Tiagabine