Effect of Anti-inflammatory Treatment with AMD3100 and CX3CR1 Deficiency on GABAA Receptor Subunit and Expression of Glutamate Decarboxylase Isoforms After Stroke

Georgios Michalettos,Tadeusz Wieloch,Daniela Talhada,Ana Rita Pombo Antunes,Karsten Ruscher,Helene L Walter

doi:10.1007/s12035-021-02510-x

Georgios Michalettos, Tadeusz Wieloch + Show 4 more

Open Access

https://doi.org/10.1007/s12035-021-02510-x

Copy DOI

Abstract

Following stroke, attenuation of detrimental inflammatory pathways might be a promising strategy to improve long-term outcome. In particular, cascades driven by pro-inflammatory chemokines interact with neurotransmitter systems such as the GABAergic system. This crosstalk might be of relevance for mechanisms of neuronal plasticity, however, detailed studies are lacking. The purpose of this study was to determine if treatment with 1,1′-[1,4-phenylenebis(methylene)]bis[1,4,8,11-tetraazacyclotetradecane] (AMD3100), an antagonist to the C-X-C chemokine receptor type 4 (CXCR4) and partial allosteric agonist to CXCR7 (AMD3100) alone or in combination with C-X3-C chemokine receptor type 1 (CX3CR1) deficiency, affect the expression of GABAA subunits and glutamate decarboxylase (GAD) isoforms. Heterozygous, CX3CR1-deficient mice and wild-type littermates were subjected to photothrombosis (PT). Treatment with AMD3100 (0.5 mg/kg twice daily i.p.) was administered starting from day 2 after induction of PT until day 14 after the insult. At this time point, GABAA receptor subunits (α3, β3, δ), GAD65 and GAD67, and CXCR4 were analyzed from the peri-infarct tissue and homotypic brain regions of the contralateral hemisphere by quantitative real-time PCR and Western Blot. Fourteen days after PT, CX3CR1 deficiency resulted in a significant decrease of the three GABAA receptor subunits in both the lesioned and the contralateral hemisphere compared to sham-operated mice. Treatment with AMD3100 promoted the down-regulation of GABAA subunits and GAD67 in the ipsilateral peri-infarct area, while the β3 subunit and the GAD isoforms were up-regulated in homotypic regions of the contralateral cortex. Changes in GABAA receptor subunits and GABA synthesis suggest that the CXCR4/7 and CX3CR1 signaling pathways are involved in the regulation of GABAergic neurotransmission in the post-ischemic brain.

Highlights

Stroke remains the leading cause of disability worldwide [1]
Cx3cr1 knockout mice subjected to PT showed a decrease in the mRNA levels of the GABAA subunits α3, β3, and δ in the ipsi- and contralateral hemisphere compared to sham/naïve mice of both genotypes (Fig. 2)
This decrease was more profound on the contralateral non-lesioned cortex with knockout mice subjected to PT exhibiting significantly lower mRNA levels of all three GABAA subunits compared to wt/hz littermates after PT (Fig. 2)

Summary

Introduction

Stroke remains the leading cause of disability worldwide [1]. Neurological deficits are the result of lost neuronal function and network integrity due to acute tissue demise and are perpetuated by delayed neuronal dysfunction and delayed neuronal cell death. Electrophysiological studies coupled with knockout experiments on the neuronal excitability in the peri-infarct area have demonstrated increased tonic inhibition mediated partially by α5- and δ-containing receptors. Pharmacological antagonism on these receptors resulted in improved outcome [12]. A down-regulation of α4 and δ subunits in cortical layers 2 and 3 in the peri-infarct area after transient middle cerebral artery occlusion (tMCAO) resulted in decreased tonic inhibition This was associated with improved motor performance but increased susceptibility to epileptic seizures [13]

Objectives

Methods

Results

Conclusion