Interaction of topiramate with glycine receptor channels

Department of Neurology, Medical University Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
Pharmacological Research (Impact Factor: 4.41). 07/2005; 51(6):587-92. DOI: 10.1016/j.phrs.2005.02.021
Source: PubMed


Glycine receptor channels are pentameric ligand-gated ion channels that respond to the application of inhibitory neurotransmitters by opening of a chloride-selective central pore. Topiramate (TPM) is a broad-spectrum antiepileptic drug used as add-on or monotherapy for focal seizures. In the present study the interaction of TPM with glycine receptor channels was studied on outside-out patches from HEK293 cells expressing alpha1beta glycine receptor channels. The patch clamp techniques combined with ultra fast solution exchange enabled us to investigate the kinetics of receptor channels in presence of TPM. Our study showed no agonistic or potentiating effect for TPM on glycine receptor channels. However, in presence of 1 mM glycine + 1 mM TPM, the desensitization got faster and the peak current amplitude decreased. After the end of glycine + TPM pulses, off-currents occurred, suggestive for a specific channel block mechanism.

3 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Alcohol dependence is a complex disorder affecting all social and ethnic groups. Although the scientific understanding of the mechanism governing this multifactorial disease is still in its infancy, understanding its biological bases, including the potential contribution of genetic factors, is key to characterizing individual's risk and developing efficacious therapeutic target to combat the disease. This review provides an overview of different approaches that are being increasingly integrated to extend our knowledge of the genetic underpinnings of alcohol dependence.
    Journal of Addictive Diseases 07/2013; 32(3):293-309. DOI:10.1080/10550887.2013.824329 · 1.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The substantia nigra pars reticulata (SNR) is known to play a role in gating and control of seizures. Prompted by the observation that intrahippocampal topiramate (TPM) administration does not suppress limbic seizures in the focal pilocarpine model, we investigated the role of the SNR in the anticonvulsant mechanism of action of TPM. Limbic seizures were evoked in freely moving rats by intrahippocampal administration of pilocarpine via a microdialysis probe. Changes in hippocampal extracellular (EC) glutamate and GABA concentrations were monitored. Effects of intraperitoneal (10-200 mg/kg), intrahippocampal (1-5 mM), and bilateral intranigral (100-300 nmol) TPM administration on pilocarpine-induced seizures and neurochemical changes were evaluated. Effects of TPM administration alone on hippocampal and nigral EC amino acid concentrations were also studied. Systemic and intranigral, but not intrahippocampal TPM administration suppressed pilocarpine-induced seizures and neurochemical changes. Nigral GABA(A) receptor blockade by picrotoxin abolished the anticonvulsant effect of TPM in SNR. Systemic TPM administration increased hippocampal glutamate and decreased GABA. Intranigral TPM administration increased hippocampal glutamate, but not GABA. Intrahippocampal TPM increased hippocampal glutamate and GABA, but only at high concentrations. In the focal pilocarpine model, TPM does not exert its anticonvulsant effect at the site of seizure initiation. We identified the SNR as a site of action of TPM, and showed that the nigral GABA-ergic system is central to TPM's anticonvulsant effect in SNR. Anticonvulsant effects and neurochemical changes in hippocampus following intranigral TPM administration suggest the existence of a nigro-hippocampal circuit, which may be involved in the control of limbic seizures.
    Epilepsia 10/2006; 47(9):1519-35. DOI:10.1111/j.1528-1167.2006.00625.x · 4.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Medical management and drug development for epilepsy emphasizes increasing pharmacological specificity to improve efficacy while minimizing side effects. However, growing evidence supports potential benefits of "magic shotgun" over "magic bullet" approaches to treatment of complex disease processes. We discuss experimental and theoretical evidence suggesting that seizures may be more amenable to a multi-target rather than a high-specificity approach, including evidence that individual anticonvulsants directly modulate a variety ion channel targets, the most direct determinants of neuronal excitability. Although the relevance of this promiscuity remains untested, it may contribute to anticonvulsant efficacy and should therefore be considered in drug development strategies and in therapeutic decision making.
    Medical Hypotheses 12/2008; 72(3):297-305. DOI:10.1016/j.mehy.2008.09.049 · 1.07 Impact Factor