Neuroprotection by Exogenous Neuregulin-1 in a Mouse Model of Temporal Lobe Epilepsy
Abstract number :
1.01
Submission category :
1. Basic Mechanisms / 1A. Epileptogenesis of acquired epilepsies
Year :
2021
Submission ID :
1825770
Source :
www.aesnet.org
Presentation date :
12/4/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:50 AM
Authors :
Allison Peterson, - University of California, Riverside; Devin Binder, MD, PhD - Professor, Biomedical Sciences, University of California, Riverside; Byron Ford, PhD - Associate Dean, Pre-Clerkship Medical Education, Biomedical Sciences, University of California; Terese Garcia, BS - University of California, Riverside
Rationale: Temporal lobe epilepsy (TLE) is the most common form of epilepsy with focal seizures. Approximately 30% of patients suffer from refractory epilepsy whose seizures cannot be controlled with currently available antiepileptic drugs (AEDs). It is crucial we develop alternative therapeutics that target the underlying disease which could aid in treating patients with refractory TLE. Previous studies have also shown that neuregulin-1 (NRG-1), a growth factor with various functions in the central nervous system, increases glutamate uptake and is neuroprotective in various animal models of brain injury. In this study, we examine the regulation of endogenous NRG-1-ErbB4 signaling in epilepsy and determine the therapeutic effects of exogenous NRG-1 treatment at early phases of epileptogenesis.
Methods: 8-10-week-old CD1 male mice were injected with 64 nL of 20 mM kainic acid or 0.9% saline into the dorsal hippocampus to induce status epilepticus. Mice were given either NRG-1 (25 µg/kg/day) or vehicle (0.1% BSA) intraperitoneal daily for 7 days following kainic acid injection. Mice were euthanized at 7 days post-IHKA for immunohistochemistry. Sections were incubated overnight at 4oC in 10% bovine serum albumin with primary antibodies to NRG-1 (Abcam ab2324), ErbB4 phospho Y1284 (Abcam ab61059), GFAP (Abcam ab7260), EAAT3 (Abcam ab124802), and NeuN (EMD Millipore ABN78). Sections were then incubated with secondary antibodies conjugated with Alexa 488-tyramide or Alexa 594 for visualization.
Results: Phospho-ErbB4 immunoreactivity in the ipsilateral hippocampus revealed a main effect of treatment (t(df) = 1.156(7), p = 0.0467). Phospho-ErbB4 immunoreactivity in the contralateral hippocampus revealed a main effect of treatment (p = 0.0148). NRG-1 immunoreactivity was also significantly increased in the hippocampus ipsilateral to injection (p = 0.0018). Hippocampal EAAT3 immunoreactivity was also significantly increased in both hippocampi of NRG-1 treated mice (p < 0.05). Quantification of NeuN-immunoreactive neurons was examined in S. pyramidale of CA1, S. pyramidale of CA3, and dentate gyrus for both hippocampi. NeuN immunoreactivity in the dentate gyrus of the ipsilateral hippocampus revealed a main effect of treatment (p = 0.0192). Immunoreactivity in S. pyramidale of CA3 in the contralateral hippocampus revealed a main effect of treatment (p = 0.0028). Immunoreactivity in the dentate gyrus of the contralateral hippocampus revealed a main effect of treatment (p = 0.0095).
Conclusions: In this study, we used immunohistochemistry to demonstrate upregulation of endogenous NRG-ErbB4 signaling in the epileptic brain while exogenous NRG-1 treatment is neuroprotective at early time points during epileptogenesis. In summary, we report that treatment with NRG-1 upregulates glutamate transporter EAAT3 and is neuroprotective in the epileptic brain. We hypothesize that glutamate transporter dysregulation contributes to the development of epilepsy and modulation of glutamate transport could lead to novel therapeutics for the treatment of refractory epilepsies.
Funding: Please list any funding that was received in support of this abstract.: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Basic Mechanisms