Inhibition of ERK1/2 signaling prevents epileptiform behavior in rats prone to audiogenic seizures.

It has recently been proposed that extracellular signal-regulated kinases 1 and 2 (ERK1/2) are one of the factors mediating seizure development. We hypothesized that inhibition of ERK1/2 activity could prevent audiogenic seizures by altering GABA and glutamate release mechanisms. Krushinsky-Molodkina rats, genetically prone to audiogenic seizure, were recruited in the experiments. Animals were i.p. injected with an inhibitor of ERK1/2 SL 327 at different doses 60 min before audio stimulation. We demonstrated for the first time that inhibition of ERK1/2 activity by SL 327 injections prevented seizure behavior and this effect was dose-dependent and correlated with ERK1/2 activity. The obtained data also demonstrated unchanged levels of GABA production, and an increase in the level of vesicular glutamate transporter 2. The study of exocytosis protein expression showed that SL 327 treatment leads to downregulation of vesicle-associated membrane protein 2 and synapsin I, and accumulation of synaptosomal-associated protein 25 (SNAP-25). The obtained data indicate that the inhibition of ERK1/2 blocks seizure behavior presumably by altering the exocytosis machinery, and identifies ERK1/2 as a potential target for the development of new strategies for seizure treatment. Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are one of the factors mediating seizure development. Here we report that inhibition of ERK1/2 by SL 327 prevented seizure behavior and this effect was dose-dependent and correlated with ERK1/2 activity. Accumulation of VGLUT2 was associated with differential changing of synaptic proteins VAMP2, SNAP-25 and synapsin I. The obtained data indicate that the inhibition of ERK1/2 alters neurotransmitter release by changing the exocytosis machinery, thus preventing seizures.

[Induction of NO-synthase and glial fibrillary acidic protein in astrocytes of the temporal cortex in rats with audiogenic epileptiform reaction]. / Induktsiia NO-sintazy i glial'nogo kislogo fibrilliarnogo belka v astrotsitakh visochnoi kory krys s audiogennoi épileptiformnoi reaktsiei.

The localization of NADPH-diaphorase (NADPH-d), inducible NO-synthase (iNOS) and glial fibrillary acidic protein (GFAP) was studied in the astrocytes of the temporal cortex in rats of Krushinsky-Molodkina strain which are genetically prone to audiogenic seizures. The seizure was evoked by thrice-repeated acoustic stimulation. Wistar rats and acoustically untreated seizure-free Krushinsky-Molodkina rats were used as a control. The foci of brain damage were consistently found in the neocortex of the animals with audiogenic seizures. Epileptic foci, 300-400 microm in diameter, were localized in layers III-V; they were found to consist of the clusters of NADPH-d-positive astrocytes and to be present in both hemispheres. In the foci of cortical damage astrocytes expressed iNOS and an elevated level of GFAP. The number of GFAP-immunopositive astrocytes in the foci of damage was increased by 25-37% compared to the control and to undamaged areas of the cortex. Astrocyte NOS and GFAP induction found in this work, suggests the participation of glia in compensatory NO-dependent mechanisms, that are formed in the damage foci of neocortex during the audiogenic seizures.

Transplantation of M213-2O cells with enhanced GAD67 expression into the inferior colliculus alters audiogenic seizures.

The purpose of the present study was to examine the effects of GABA-producing cell transplants on audiogenic seizures (AGS). The M213-2O cell line was derived from fetal rat striatum and has GABAergic properties. This cell line was further modified to express human GAD(67) and produce elevated levels of GABA. The present study compares the effects of parent M213-2O cell transplants with those of GAD(67)-modified M213-2O cells in AGS-prone Long-Evans rats. Two weeks following implantation of engineered cells, latency to AGS-typical wild running was increased compared to nonimplanted subjects. Survival of the transplanted cells was confirmed by immunochemical labeling of GAD(67) and Epstein-Barr virus nuclear antigen. These findings support the use of GABA-producing cell lines to modify seizure activity.