Neuroprotective Effect of AM404 Against NMDA-Induced Hippocampal Excitotoxicity

Soraya Wilke Saliba,Tsvetan Serchov,Tiziana Bonifacino,Giambattista Bonanno,Bernd L Fiebich,Antônio Carlos Pinheiro De Oliveira

doi:10.3389/fncel.2019.00566

Abstract

Different studies have demonstrated that inflammation and alterations in glutamate neurotransmission are two events contributing to the pathophysiology of neurodegenerative or neurological disorders. There are evidences that N-arachidonoylphenolamine (AM404), a cannabinoid system modulator and paracetamol metabolite, modulates inflammation and exerts neuroprotective effects on Huntington’s (HD) and Parkinson’s diseases (PD), and ischemia. However, the effects of AM404 on the production of inflammatory mediators and excitotoxicity in brain tissue stimulated with N-methyl-D-aspartic acid (NMDA) are not elucidated. In this present study, we investigated the effects of AM404 on the production of inflammatory mediators and neuronal cell death induced by NMDA in organotypic hippocampal slices cultures (OHSC) using qPCR, western blot (WB), and immunohistochemistry. Moreover, to comprehend the mechanism of excitotoxicity, we evaluated the effects of AM404 on glutamate release in hippocampal synaptosomes and the NMDA-induced calcium responses in acute hippocampal slices. Our results showed that AM404 led to a significant decrease in cell death induced by NMDA, through a mechanism possibly involving the reduction of glutamate release and the calcium ions responses. Furthermore, it decreased the expression of the interleukin (IL)-1β. This study provides new significant insights about the anti-inflammatory and neuroprotection effects of AM404 on NMDA-induced excitotoxicity. To understand the effects of AM404 in these processes might contribute to the therapeutic potential of AM404 in diseases with involvement of neuroinflammation and neurodegeneration and might lead to a possible future treatment of neurodegenerative diseases.

Highlights

The role of excitotoxicity in the etiology or progression of several human neurodegenerative disorders such as Alzheimer’s (AD), Parkinson’s (PD) and Huntington’s (HD) diseases, epilepsy or amyotrophic lateral sclerosis (ALS) has been proposed (Palop et al, 2006; Dong et al, 2009)
The effects of AM404 on the excitotoxicity and production of inflammatory mediators in brain tissue stimulated with N-methyl-D-aspartic acid (NMDA) are not elucidated. In this current study, we evaluated if AM404 is able to prevent NMDA-induced excitotoxicity and inflammation by evaluating cell death and inflammatory parameters in organotypic hippocampal slices cultures (OHSC), glutamate release in synaptosomes, and intracellular calcium responses in acute hippocampal slices stimulated with NMDA
We studied whether AM404 has a neuroprotective effect on excitotoxicity induced by NMDA in OHSC

Summary

Introduction

The role of excitotoxicity in the etiology or progression of several human neurodegenerative disorders such as Alzheimer’s (AD), Parkinson’s (PD) and Huntington’s (HD) diseases, epilepsy or amyotrophic lateral sclerosis (ALS) has been proposed (Palop et al, 2006; Dong et al, 2009). Some studies have suggested that the endocannabinoid system plays a protective role against excitotoxic damage (Marsicano et al, 2003; Mechoulam, 2003; Veldhuis et al, 2003), mostly via cannabinoid CB1 receptor inhibiting N-type Ca2+ channels activity and reduces glutamatergic transmission (Shen et al, 1996; Lévénès et al, 1998; van der Stelt et al, 2002). The CB1 receptor is the most abundant G protein-coupled receptor in the brain (Howlett et al, 1990, 2010) and it is expressed on glutamatergic and GABAergic neurons in brain regions such as the hippocampus, cortex, and basal ganglia (Tsou et al, 1998; Mackie, 2005). TRPV1 is a non-selective cation channel and expressed in numerous regions in the brain, including cortex, hippocampus, and corpus callosum (Tóth et al, 2005)

Methods

Results

Discussion

Conclusion