Abstract
In epilepsy, allegedly, a neurotransmitter imbalance between the inhibitory GABA and the excitatory glutamate prevails. Therefore, some antiepileptic drugs (AEDs) are thought to increase GABA release. Because little is known about corresponding presynaptic effects of AEDs in the human brain, this study investigated the effects of carbamazepine, lamotrigine, phenytoin, gabapentin, pregabalin, levetiracetam, and valproate on 3H-GABA release from human neocortical synaptosomes preincubated with 3H-GABA. To obtain information on possible species differences, rat neocortical synaptosomes were investigated concomitantly. Release was evoked by either veratridine (1, 3.2, or 10 μM), which prevents activated voltage-dependent Na+ channels from closing, or elevation of extracellular [K+] from 3 to 15 mM. The exocytosis inhibitor tetanus toxin (TeT) or withdrawal of buffer Ca2+ (Ca 2+e ) reduced K+-evoked release in both species, while blockade of Na+ channels with tetrodotoxin had no effect. K+-evoked release was characterized as predominant, Ca2+-dependent and Na+-independent, exocytosis. Carbamazepine and phenytoin in the rat and carbamazepine, phenytoin, lamotrigine, and valproate in human tissue reduced K+-evoked 3H-GABA release. With respect to veratridine-evoked release, Ca 2+e withdrawal did not reduce release in the rat; it even increased the release in human tissue. TeT was slightly inhibitory in the rat. Blockade of GABA transport diminished veratridine-evoked 3H-GABA release in either species. This release was characterized as mediated mainly by transporter reversal. Carbamazepine, lamotrigine, and phenytoin in rat tissue and carbamazepine and phenytoin in human decreased veratridine-induced 3H-GABA release. Interestingly, no AED increased 3H-GABA release. The reduction by AEDs of veratridine-evoked release was more intense than that of K+-evoked release. In conclusion, reduction of GABA release by AEDs may be the actual objective in a pathologically altered neuronal network where GABA acts in a depolarizing fashion.
Similar content being viewed by others
References
Altman DG (1991) Statistics in medical journals: developments in the 1980 s. Stat Med 10:1897–1913
Armijo JA, Shushtarian M, Valdizan EM, Cuadrado A, de las Cuevas I, Adín J (2005) Ion channels and epilepsy. Curr Pharm Des 11:1975–2003
Attwell D, Barbour B, Szatkowski M (1993) Nonvesicular release of neurotransmitter. Neuron 11:401–407
Berry D, Millington C (2005) Analysis of pregabalin at therapeutic concentrations in human plasma/serum by reversed-phase HPLC. Ther Drug Monit 27:451–456
Borden LA, Murali Dhar TG, Smith KE, Weinshank RL, Branchek TA, Gluchowski C (1994) Tiagabine, SK&F 89976-A, CI-966, and NNC-711 are selective for the cloned GABA transporter GAT-1. Eur J Pharmacol 269:219–224
Brawek B, Löffler M, Weyerbrock A, Feuerstein TJ (2009) Effects of gabapentin and pregabalin on K+-evoked 3H-GABA and 3H-glutamate release from human neocortical synaptosomes. Naunyn-Schmiedeberg's arch Pharmacol 379:361–369
Cammack JN, Rakhilin SV, Schwartz EA (1994) A GABA transporter operates asymmetrically and with variable stoichiometry. Neuron 13:949–960
Cheung H, Kamp D, Harris E (1992) An in vitro investigation of the action of lamotrigine on neuronal voltage-activated sodium channels. Epilepsy Res 13:107–112
Cohen I, Navarro V, Clemenceau S, Baulac M, Miles R (2002) On the origin of interictal activity in human temporal lobe epilepsy in vitro. Science 298:1418–1421
Cohen I, Navarro V, Le Duigou C, Miles R (2003) Mesial temporal lobe epilepsy: a pathological replay of developmental mechanisms? Bio Cell 95:329–333
Crowder JM, Bradford HF (1987) Common anticonvulsants inhibit Ca2+ uptake and amino acid neurotransmitter release in vitro. Epilepsia 28:378–382
Errante LD, Petroff OA (2003) Acute effects of gabapentin and pregabalin on rat forebrain cellular GABA, glutamate, and glutamine concentrations. Seizure 12:300–306
Errante LD, Williamson A, Spencer DD, Petroff OA (2002) Gabapentin and vigabatrin increase GABA in the human neocortical slice. Epilepsy Res 49:203–210
Fink K, Meder W, Dooley DJ, Göthert M (2000) Inhibition of neuronal Ca2+ influx by gabapentin and subsequent reduction of neurotransmitter release from rat neocortical slices. Br J Pharmacol 130:900–906
Fink K, Dooley DJ, Meder WP, Suman-Chauhan N, Duffy S, Clusmann H, Göthert M (2002) Inhibition of neuronal Ca2+ influx by gabapentin and pregabalin in the human neocortex. Neuropharmacology 42:229–236
Gee NS, Brown JP, Dissanayake VU, Offord J, Thurlow R, Woodruff GN (1996) The novel anticonvulsant drug, gabapentin (Neurontin), binds to the alpha2delta subunit of a calcium channel. J Biol Chem 271:5768–5776
Johannessen SI, Battine D, Berry DJ, Bialer M, Krämer G, Tomson T, Patsalos PN (2003) Therapeutic drug monitoring of the newer antiepileptic drugs. Ther Drug Monit 25:347–363
Kammerer M, Rassner M, Freiman TM, Feuerstein TJ (2010) Effects of antiepileptic drugs on GABA release in rat and human neocortical synaptosomes. Naunyn-Schmiedeberg's arch Pharmacol 381(Suppl 1):47
Kammerer M, Brawek B, Freiman TM, Jackisch R, Feuerstein TJ (2011) Effects of antiepileptic drugs on glutamate release from rat and human neocortical synaptosomes. Naunyn-Schmiedeberg’s Arch Pharmacol (in press)
Kelly MK, Gross RA, Macdonald RL (1990) Valproic acid selectively reduces the low-threshold (T) calcium current in rat nodose neurons. Neurosci Lett 166:233–238
Landmark CJ (2007) Targets for antiepileptic drugs in the synapse. Med Sci Monit 13:1–7
Lanneau C, Green A, Hirst WD, Wise A, Brown JT, Donnier E, Charles KJ, Wood M, Davies Ch, Pangalos MN (2001) Gabapentin is not a GABAB receptor agonist. Neuropharmacology 41:965–975
Leach MJ, Marden CM, Miller AA (1986) Pharmacological studies on lamotrigine, a novel potential antiepileptic drug: II. Neurochemical studies on the mechanism of action. Epilepsia 27:490–497
Leach JP, Sills GJ, Butler E, Forrest G, Thompson GG, Brodie MJ (1997) Neurochemical actions of gabapentin in mouse brain. Epilepsy Res 27:175–180
Levi G, Gallo V, Raiteri M (1980) A reevaluation of veratridine as a tool for studying the depolarization-induced release of neurotransmitters from nerve endings. Neurochem Res 5:281–295
Löscher W, Böhme G, Schäfer H, Kochen W (1981) Effect of metabolites of valproic acid on the metabolism of GABA in brain and brain nerve endings. Neuropharmacology 20:1187–1192
Lu CC, Hilgemann DW (1999) GAT1 (GABA:Na+:Cl−) cotransport function. Steady state studies in giant Xenopus oocyte membrane patches. J Gen Physiol 114:429–444
Lynch BA, Lambeng N, Nocka K, Kensel-Hammens P, Bajjalieh SM, Matagne A, Fuks B (2004) The synaptic vesicle protein SV2A is the binding site for the antiepileptic drug levetiracetam. Proc Natl Acad Sci USA 101:9861–9866
Macdonald RL, McLean MJ (1982) Cellular bases of barbiturate and phenytoin anticonvulsant drug action. Epilepsia 23:7–18
Mann EO, Mody I (2008) The multifaceted role of inhibition in epilepsy: seizure-genesis through excessive GABAergic inhibition in autosomal dominant nocturnal frontal lobe epilepsy. Curr Opin Neurol 21:155–160
Mantovani M, Moser A, Haas CA, Zentner J, Feuerstein TJ (2009) GABAA autoreceptors enhance GABA release from human neocortex: towards a mechanism for high-frequency stimulation (HFS) in brain? Naunyn-Schmiedberg´s arch Pharmacol 380:45–58
McLean MJ, Macdonald RL (1986a) Sodium valproate, but not ethosuximide, produces use- and voltage-dependent limitation of high frequency repetitive firing of action potentials of mouse central neurons in cell culture. J Pharmacol Exp Ther 237:1001–1011
McLean MJ, Macdonald RL (1986b) Carbamazepine and 10,11-epoxycarbamazepine produce use- and voltage-dependent limitation of rapidly firing action potential of mouse central neurons in cell culture. J Pharmacol Exp Ther 238:727–738
McMahon HT, Nicholls DG (1991) The bioenergetics of neurotransmitter release. Biochim Biophys Acta 1059:243–264
Micheva KD, Taylor CP, Smith SJ (2006) Pregabalin reduces the release of synaptic vesicles from cultured hippocampal neurons. Mol Pharmacol 70:467–476
Minc-Golomb D, Eimerl S, Levy Y, Schramm M (1988) Release of D-[3H]aspartate and [14C]GABA in rat hippocampus slices: effects of fatty acid-free bovine serum albumin and Ca2+ withdrawal. Brain Res 457:205–211
Morris RG, Black AB, Harris AL, Batty AB, Sallustio BC (1998) Lamotrigine and therapeutic drug monitoring: retrospective survey following the introduction of a routine service. Br J Clin Pharmacol 46:547–551
Nicholls DG (1993) The glutamatergic nerve terminal. Eur J Biochem 212:613–631
Phillips NI, Fowler LJ (1982) The effects of sodium valproate on γ-aminobutyrate metabolism and behaviour in naïve and ethanolamine-O-sulphate pretreated rats and mice. Biochem Pharmacol 31:2257–2261
Rivera C, Voipio J, Payne JA, Ruusuvuori E, Lahtinen H, Lamsa K, Pirvola U, Saarma M, Kaila K (1999) The K+/Cl− co-transporter KCC2 renders GABA hyperpolarizing during neuronal maturation. Nature 397:251–255
Rogawski MA, Löscher W (2004) The neurobiology of antiepileptic drugs. Nat Rev Neurosci 5:553–564
Santos MS, Rodriguez R, Carvalho AP (1992) Effect of depolarizing agents on the Ca2+-independent and Ca2+-dependent release of [3H]GABA from sheep brain synaptosomes. Biochem Pharmacol 44:301–308
Schumacher TB, Beck H, Steinhäuser C, Schramm J, Elger CE (1998) Effects of phenytoin, carbamazepine, and gabapentin on calcium channels in hippocampal granule cells from patients with temporal lobe epilepsy. Epilepsia 39:355–363
Sitges M, Guarneros A, Nekrassov V (2007) Effect of carbamazepine, phenytoin, valproic acid, oxcarbazepine, lamotrigine, topiramate and vinpocetine on the presynaptic Ca2+ channel-mediated release of [3H]-glutamate: comparison with the Na + channel-mediated release. Neuropharmacology 53:854–862
Staley KJ, Proctor WR (1999) Modulation of mammalian dendritic GABAA receptor function by the kinetics of Cl− and HCO −3 transport. J Physiol 519:693–712
Twombly DA, Yoshii M, Narahashi T (1988) Mechanisms of calcium channel block by phenytoin. J Pharmacol Exp Ther 246:189–195
von Wegerer J, Heßlinger B, Berger M, Walden J (1997) A calcium antagonistic effect of the new antiepileptic drug lamotrigine. Eur Neuropharmacol 7:77–81
Voso MT et al (2009) Valproic acid at therapeutic plasma levels may increase 5-azacytidine efficacy in higher risk myelodysplastic syndromes. Clin Cancer Res 15:5002–5007
Walden J, Grunze H, Bingmann D, Liu Z, Düsing R (1992) Calcium antagonistic effects of carbamazepine as a mechanism of action in neuropsychiatric disorders: studies in calcium dependent model epilepsies. Eur Neuropsychopharmacol 2:455–462
Waldmeier PC, Baumann PA, Wicki P, Feldtrauer JJ, Stierlin C, Schmutz M (1995) Similar potency of carbamazepine, oxcarbazepine, and lamotrigine in inhibiting the release of glutamate and other neurotransmitters. Neurology 45:1907–1913
Wu Y, Wang W, Diez-Sampedro A, Richerson GB (2007) Nonvesicular inhibitory neurotransmission via reversal of the GABA transporter GAT-1. Neuron 56:851–865
Author information
Authors and Affiliations
Corresponding author
Additional information
M. Kammerer and M. P. Rassner contributed equally to this work.
Rights and permissions
About this article
Cite this article
Kammerer, M., Rassner, M.P., Freiman, T.M. et al. Effects of antiepileptic drugs on GABA release from rat and human neocortical synaptosomes. Naunyn-Schmiedeberg's Arch Pharmacol 384, 47–57 (2011). https://doi.org/10.1007/s00210-011-0636-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00210-011-0636-8