Chemogenetic suppression of pharmacologically induced frontal lobe epilepsy in a macaque monkey
Abstract number :
3.399
Submission category :
2. Translational Research / 2B. Devices, Technologies, Stem Cells
Year :
2021
Submission ID :
1886475
Source :
www.aesnet.org
Presentation date :
12/9/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:56 AM
Authors :
Naohisa Miyakawa, PhD - National Institutes for Quantum Science and Technology; Yuji Nagai, DVM, PhD – Department of Functional Brain Imaging – National Institutes for Quantum Science and Technology; Keisuke Kawasaki, PhD – Department of Physiology – Niigata University School of Medicine; Yukiko Hori, PhD – National Institutes for Quantum Science and Technology – Department of Functional Brain Imaging; Kei Oyama, PhD – Department of Functional Brain Imaging – National Institutes for Quantum Science and Technology; Asumi Orihara, MD – National Institutes for Quantum Science and Technology – Department of Functional Brain Imaging; Takeshi Matsuo, MD, PhD – Tokyo Metropolitan Neurological Hospital; Takafumi Suzuki, D.Eng – Center for Information and Neural Networks – National Institute of Information and Communications Technology; Ken-ichi Inoue, PhD – Kyoto University – Primate Research Institute; Masahiko Takada, PhD – Primate Research Institute – Kyoto University; Tetsuya Suhara, MD, PhD – Institute for Quantum Life Science – National Institutes for Quantum Science and Technology; Makoto Higuchi, MD, PhD – Department of Functional Brain Imaging – National Institutes for Quantum Science and Technology; Takafumi Minamimoto, PhD – Department of Functional Brain Imaging – National Institutes for Quantum Science and Technology
Rationale: Medical treatments and surgical lesions of epilepsy sometimes lead to unexpected side effects by affecting the surrounding normal tissues, and therefore, a more focused and on-demand approach is desirable. DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) is a recently developed “chemogenetics” tool that combines genetically introduced functional proteins (artificial receptors) and pharmacologically introduced chemicals (actuator drugs), offering focused and on-demand control of neuronal activities. We have recently developed a potent and selective actuator drug, Deschloroclozapine (DCZ), whose radiolabeled form can be used as a PET tracer to monitor DREADD expression in vivo. This study examined the utility of DREADDs on epilepsy treatment using a pharmacological model of epilepsy in a non-human primate (NHP).
Methods: We injected virus vectors carrying hM4Di, an inhibitory DREADD gene (AAV2.1-hSyn-FLAG-hM4Di-IRES-AcGFP) to the putative hand/arm-region of the motor cortex in a cynomolgus macaque. Five weeks after the vector injection, hM4Di expression was confirmed using PET imaging with [11C]DCZ. We performed additional surgery to open a cranial window and placed an epidural electrocorticogram (ECoG) electrode array and a chronic chamber to approach the target region. Acute injections of bicuculline methiodide (6~12 µg) into the hM4Di-expressing region were conducted to start artificial epilepsy. DCZ (100~200 µg/kg) or control vehicle (2% DMSO in saline) were injected intramuscularly while we monitored the ECoG and video for seizure and body responses. Nissl and anti-GFP antibody staining were performed after the animal was euthanized, and cardially fixated.
Results: Bicuculline injection caused paroxysmal cortical discharges with twitching and stiffening of the right arm. Recurrent cortical discharges (status epilepticus) spreading over a wider area of the cortex soon followed coinciding with hemi- and whole-body convulsions. Intramuscular injection of DCZ (100~200 µg/kg), but not the control vehicle (2% DMSO in saline), attenuated the body convulsions and spreading of recurrent seizures. Post-mortem histology confirmed the preserved cell condition of the DCZ-expressing cortex, but with some reduction of the layer 5 large pyramidal cells in the bicuculline-injected subregion.
Conclusions: Although further study is needed, these preliminary results are the first to demonstrate in an NHP model that epilepsy can be suppressed using the DREADD system, suggesting its promising utility for future clinical applications.
Funding: Please list any funding that was received in support of this abstract.: QST President's Strategic Grant (Creative Research) (to NM); MEXT/JSPS KAKENHI Grant Numbers JP19K07811, JP20H04596, (to NM), JP19K08138 (to YN), 18H04037 (to T Minamimoto); AMED Grant Numbers JP19dm0107146 (to T Minamimoto).
Translational Research