, 2004). Therefore, despite efforts to link GluK2 to HD, it seems unlikely that KARs are involved in the direct pathogenesis of this disease. There are several lines of evidence strongly suggesting that KARs might be involved in the excitatory EPZ6438 to inhibitory imbalances linked to epilepsy. Actually, KA injection has served as an animal model that reproduces details of human temporal lobe epilepsy (TLE). The inhibition of GABA release and the activation of postsynaptic KARs might account for the acute epileptogenic effect of KA (Rodríguez-Moreno

et al., 1997), although these events do not explain the chronic epilepsy generated months after KA treatment. Actually, the seizures provoked initiate a number of molecular changes and morphological rearrangements in structures with a low epileptogenic threshold, such as the hippocampus. For instance, it is well known that sprouting of glutamatergic fibers takes place in both the KA model of TLE and in human patients and, accordingly, a large number LBH589 nmr of aberrant synapses are established de novo. These functional aberrant synapses made on granule cells of the dentate gyrus are sprouted MFs and they incorporate KARs, which provide a substantial component of the excitatory input (Epsztein et al., 2005). Thus,

aberrant KAR-operated synapses formed under pathological conditions represent a morphological substrate likely to participate in the pathogenesis of TLE (Artinian et al., 2011). The data available from human epileptic tissue indicates an upregulation of GluK1 in the hippocampus of pharmacoresistant

TLE patients (e.g., ADAMTS5 Li et al., 2010), suggesting that rearrangements in neural circuits involving KARs could also take place in humans suffering epilepsy. Although these data should be considered with care due to the poor specificity of some KAR antibodies (e.g., GluK1), it raises the possibility of designing antiepileptic therapies based on the antagonism of KARs. Consistent with KARs influencing this imbalance, the genetic elimination of GluK2 subunits in mice reduced their sensitivity to develop seizures after KA injections (Mulle et al., 1998), illustrating that these receptors contribute to the establishment of overexcitability by exogenous KA that leads to epilepsy. Similarly, exogenous KA reduced GABA release in slices (Clarke et al., 1997 and Rodríguez-Moreno et al., 1997), dramatically preventing the recurrent inhibition of hippocampal principal neurons in vivo and provoking epileptic activity (Rodríguez-Moreno et al., 1997). According to these data, constituting the strongest evidence of the potential therapeutic utility of KARs, a consortium of academic and industry groups (Smolders et al., 2002) showed that antagonists of GluK1 (i.e., LY377770 and LY382884) prevent the development of epileptic activity in the CA3 area of hippocampal slices in a model of pilocarpine-induced epileptiform activity.