Temporal lobe epilepsy is a common, chronic neurologic disorder characterized by recurrent spontaneous seizures. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate posttranscriptional expression of protein-coding mRNAs, which may have important roles in the pathogenesis of neurologic disorders. In models of prolonged, injurious seizures (status epilepticus) and in experimental and human epilepsy, we found up-regulation of miR-134, a brainspecific, activity-regulated miRNA implicated in the control of dendritic spine morphology. Silencing of miR-134 expression in vivo using antagomirs reduced hippocampal CA3 pyramidal neuron dendrite spine density by 21%, and rendered mice refractory to seizures and hippocampal injury caused by status epilepticus. Depletion of miR-134 after status epilepticus reduced the later occurrence of spontaneous seizures by over 90% and mitigated attendant pathologic features of temporal lobe epilepsy. Thus, silencing miR-134 exerts prolonged seizure suppressant and Users may view, print, copy, download and text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

When an otherwise harmful insult to the brain is preceded by a brief, noninjurious stimulus, the brain becomes tolerant, and the resulting damage is reduced. Epileptic tolerance develops when brief seizures precede an episode of prolonged seizures (status epilepticus). MicroRNAs (miRNAs) are small, noncoding RNAs that function as post-transcriptional regulators of gene expression. We investigated how prior seizure preconditioning affects the miRNA response to status epilepticus evoked by intra-amygdalar kainic acid in mice. The miRNA was extracted from the ipsilateral CA3 subfield 24 hours after focal-onset status epilepticus in animals that had previously received either seizure preconditioning (tolerance) or no preconditioning (injury), and mature miRNA levels were measured using TaqMan low-density arrays. Expression of 21 miRNAs was increased, relative to control, after status epilepticus alone, and expression of 12 miRNAs was decreased. Increased miR-132 levels were matched with increased binding to Argonaute-2, a constituent of the RNA-induced silencing complex. In tolerant animals, expression responses of >40% of the injury-group-detected miRNAs differed, being either unchanged relative to control or down-regulated, and this included miR-132. In vivo microinjection of locked nucleic acid-modified oligonucleotides (antagomirs) against miR-132 depleted hippocampal miR-132 levels and reduced seizure-induced neuronal death. Thus, our data strongly suggest that miRNAs are important regulators of seizure-induced neuronal death.

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Prolonged seizures (status epilepticus) are associated with brain region-specific regulation of apoptosis-associated signaling pathways. Bcl-2 homology domain 3-only (BH3) members of the Bcl-2 gene family are of interest as possible initiators of mitochondrial dysfunction and release of apoptogenic molecules after seizures. Previously, we showed expression of the BH3-only protein Bim increased in the rat hippocampus but not neocortex following focal-onset status epilepticus. Here, we examined Bim expression in mice and compared seizure-damage between wild-type and Bim-deficient animals. Status epilepticus induced by intra-amygdala kainic acid caused extensive neuronal death within the ipsilateral hippocampal CA3 region. Hippocampal activation of factors associated with transcriptional and post-translational activation of Bim, including CHOP and c-Jun NH(2)-terminal kinases, was significant within 1 h. Up-regulation of bim mRNA was evident after 2 h and Bim protein was increased from 4-24 h. Hippocampal CA3 neurodegeneration was reduced in Bim-deficient mice compared to wild-type animals following seizures in vivo, and short interfering RNA molecules targeting bim reduced cell death following kainic acid treatment of hippocampal organotypic cultures. In contrast, neocortical Bim expression declined after status epilepticus and neocortex damage in Bim-deficient mice was comparable to wild-type animals. These results demonstrate region-specific differential contributions of Bim to seizure-induced neuronal death. KeywordsApoptosis; Bax; Bcl-2; FKHR; Hippocampus; JNK; Neuroprotection; Temporal lobe epilepsy Signaling pathways associated with the orchestration of apoptosis may contribute to neuronal death after experimental seizures.1 Both caspase-dependent and -independent apoptosis pathways have been implicated. 1 The Bcl-2 gene family are critical upstream regulators of the mitochondrial (intrinsic) apoptotic pathways. 2 Prolonged seizures (status epilepticus), and glutamate excitotoxicity in certain models, cause mitochondrial dysfunction and release of NIH Public Access Author ManuscriptCell Death Differ. Author manuscript; available in PMC 2010 October 6. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript apoptogenic molecules, including cytochrome c ,3 and apoptosis inducing factor (AIF). 4 Support for involvement of Bcl-2 family members comes from several observations. Seizures cause multi-domain pro-apoptotic Bax to cluster around mitochondria at the time of cytochrome c release, 5 and Bax-deficient neurons have been reported to be abnormally resistant to excitotoxicity. 6 Moreover, over-expression of anti-apoptotic Bcl-xl reduces cell death after seizure-like insults in vivo ,7 and, conversely, mice deficient in anti-apoptotic Bcl-w are abnormally vulnerable to hippocampal damage after seizures. 3 However, a functional role for Bax in excitotoxicity has been excluded by some studies. 4 Also, calcium exposure of mitochondria alone, 8 and calpain activity, 9 can trigger release...

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Giant cell reparative granuloma (GCRG) is an uncommon and nonneoplastic reactive tumor that involves the maxilla and mandible in the region of the head and neck. It is rare in the nasal cavity, and it might be misdiagnosed. We reported a very aggressive GCRG with intracranial invasion, which was treated surgically via a combined approach of a lateral rhinotomy with a craniotomy by bilateral coronal incision. The pathology was consistent with GCRG. A short literature review about diagnosis, clinical behavior, and treatment of this tumor entity is given.

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