Fluoxetine accelerates epileptogenesis and magnifies disease severity in a rat model of acquired epilepsy.

OBJECTIVE: Many people with epilepsy experience comorbid anxiety and depression, and antidepressants remain a primary treatment for this. Emerging evidence suggests that these agents may modulate epileptogenesis to influence disease severity. Here, we assessed how treatment with the selective serotonin reuptake inhibitor (SSRI) antidepressant fluoxetine impacts epileptogenic, behavioral, and pathological sequelae following status epilepticus. METHODS: Male Wistar rats received kainic acid to induce status epilepticus (SE) or vehicle (sham). Animals then received either fluoxetine (10 mg/kg/day) or vehicle for 8 weeks via subcutaneous osmotic pump. Video-electroencephalography was recorded continuously until behavioral testing at day 56, including assessments of anxiety- and depression-like behavior and spatial cognition. Postmortem immunocytochemistry studies examined mossy fiber sprouting. RESULTS: Fluoxetine treatment significantly accelerated epileptogenesis following SE, reducing the average period to the first spontaneous seizure (from 32 days [vehicle] to 6 days [fluoxetine], p < .01). Also, fluoxetine exposure magnified the severity of the resultant epilepsy, increasing seizure frequency compared to vehicle (p < .01). Exposure to fluoxetine was associated with improved anxiety- and depression-like behaviors but significantly worsened cognition. Mossy fiber sprouting was more pronounced in fluoxetine-treated rats compared to vehicle (p < .0001). SIGNIFICANCE: Our studies demonstrate that, using a model exhibiting spontaneous seizures, epileptogenesis is accelerated and magnified by fluoxetine, an effect that may be related to more severe pathological neuroplasticity. The differential influence of fluoxetine on behavior indicates that different circuitry and mechanisms are responsible for these comorbidities. These findings suggest that caution should be exercised when prescribing SSRI antidepressants to people at risk of developing epilepsy.

Inflammasomes at the crossroads of traumatic brain injury and post-traumatic epilepsy.

Post-traumatic epilepsy (PTE) is one of the most debilitating consequences of traumatic brain injury (TBI) and is one of the most drug-resistant forms of epilepsy. Novel therapeutic treatment options are an urgent unmet clinical need. The current focus in healthcare has been shifting to disease prevention, rather than treatment, though, not much progress has been made due to a limited understanding of the disease pathogenesis. Neuroinflammation has been implicated in the pathophysiology of traumatic brain injury and may impact neurological sequelae following TBI including functional behavior and post-traumatic epilepsy development. Inflammasome signaling is one of the major components of the neuroinflammatory response, which is increasingly being explored for its contribution to the epileptogenic mechanisms and a novel therapeutic target against epilepsy. This review discusses the role of inflammasomes as a possible connecting link between TBI and PTE with a particular focus on clinical and preclinical evidence of therapeutic inflammasome targeting and its downstream effector molecules for their contribution to epileptogenesis. Finally, we also discuss emerging evidence indicating the potential of evaluating inflammasome proteins in biofluids and the brain by non-invasive neuroimaging, as potential biomarkers for predicting PTE development.

ComBating inter-site differences in field strength: harmonizing preclinical traumatic brain injury MRI data.

Integrating datasets from multiple sites and scanners can increase statistical power for neuroimaging studies but can also introduce significant inter-site confounds. We evaluated the effectiveness of ComBat, an empirical Bayes approach, to combine longitudinal preclinical MRI data acquired at 4.7 or 9.4 T at two different sites in Australia. Male Sprague Dawley rats underwent MRI on Days 2, 9, 28, and 150 following moderate/severe traumatic brain injury (TBI) or sham injury as part of Project 1 of the NIH/NINDS-funded Centre Without Walls EpiBioS4Rx project. Diffusion-weighted and multiple-gradient-echo images were acquired, and outcomes included QSM, FA, and ADC. Acute injury measures including apnea and self-righting reflex were consistent between sites. Mixed-effect analysis of ipsilateral and contralateral corpus callosum (CC) summary values revealed a significant effect of site on FA and ADC values, which was removed following ComBat harmonization. Bland-Altman plots for each metric showed reduced variability across sites following ComBat harmonization, including for QSM, despite appearing to be largely unaffected by inter-site differences and no effect of site observed. Following harmonization, the combined inter-site data revealed significant differences in the imaging metrics consistent with previously reported outcomes. TBI resulted in significantly reduced FA and increased susceptibility in the ipsilateral CC, and significantly reduced FA in the contralateral CC compared with sham-injured rats. Additionally, TBI rats also exhibited a reversal in ipsilateral CC ADC values over time with significantly reduced ADC at Day 9, followed by increased ADC 150 days after injury. Our findings demonstrate the need for harmonizing multi-site preclinical MRI data and show that this can be successfully achieved using ComBat while preserving phenotypical changes due to TBI.