Cannabidiol Reduces Glutamate Release from Cortical Synaptic Terminals Obtained from Epilepsy Surgery of Patients with Drug-resistant Temporal Lobe Epilepsy
Abstract number :
1.04
Submission category :
1. Basic Mechanisms / 1D. Mechanisms of Therapeutic Interventions
Year :
2022
Submission ID :
2204137
Source :
www.aesnet.org
Presentation date :
12/3/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:23 AM
Authors :
Luisa Rocha, PhD – Center for Research and Advanced Studies; Christopher Martínez-Aguirre, M. Sci. – Student, Pharmacobiology, Center for Research and Advanced Studies; Cindy Santiago-Castañeda, M. Sci. – Student, Pharmacobiology, Center for Research and Advanced Studies; Francia Carmona-Cruz, Ms. – Assistant investigator, Pharmacobiology, Center for Research and Advanced Studies; Mario Alonso-Vanegas, M.D. – Neurosurgeon, International Center for Epilepsy Surgery, HMG-Coyoacán Hospital; Manola Cuellar-Herrera, Ph.D. – Clinic of Epilepsy – General Hospital of Mexico
This abstract has been invited to present during the Basic Mechanisms platform session.
Rationale: Temporal lobe epilepsy (TLE) is the most frequent type of epilepsy. A third of the patients with TLE are drug-resistant. Drug-resistant TLE is associated with high extracellular levels of glutamate, a condition that facilitates excitotoxicity and neuronal damage. On the other hand, studies support that cannabidiol (CBD) decreases glutamate release in cell culture of microglia and in a rat model of cocaine-induced seizures. However, at present, it is unknown if CBD modifies the over-release of glutamate in the brain of patients with drug-resistant TLE. The aim of this study was to investigate if CBD reduces the evoked glutamate release in cortical synaptic terminals obtained from patients with drug-resistant TLE.
Methods: Synaptic terminals (synaptosomes) were obtained from the temporal neocortex of patients with drug-resistant TLE submitted to epilepsy surgery (n=5). Immediately after resected, the tissue was immersed in saccharose (0.32 M), oxygenated by bubbling (0.5 l/h), and transported (< 45 min) from the surgery room to the laboratory. Synaptosomes were highly purified by Percoll-sucrose density gradient and resuspended in artificial cerebrospinal fluid. Synaptosome-homogenates were divided and exposed to different concentrations of CBD (100 nM, 1 µM, 10 µM, 100 µM, or 1 mM) for 15 min. Then, membranal depolarization was evoked by the addition of KCl at 33 mM. Synaptosomes were centrifugated and the supernatant was used to estimate the glutamate release by HPLC. The results were compared with values obtained under basal conditions as well as high KCl without CBD exposure.
Results: The KCl-induced depolarization augmented the extrasynaptosomal glutamate concentration (220%, p=0.002 vs basal). The pre-exposure of synaptosomes to CBD reduced the glutamate release in a concentration dependent way (100 nM, 32%. p=0.16; 1 µM, 40%, p< 0.05; 10 µM, 40%, p< 0.05). However, CBD at higher concentrations did not induce significant changes (100 µM, p=0.2590; 10 mM, p=0.9996).
Basic Mechanisms