Electrophoretic Delivery of γ-aminobutyric Acid (GABA) into Epileptic Focus Prevents Seizures in Mice

Summary

The challenge of epilepsy research is to develop novel treatments for patients where classical therapy is inadequate. Using a new protocol—with the help of an implantable drug delivery system—we are able to control seizures in anesthetized mice by the electrophoretic delivery of GABA into the epileptic focus.

Abstract

Epilepsy is a group of neurological disorders which affects millions of people worldwide. Although treatment with medication is helpful in 70% of the cases, serious side effects affect the quality of life of patients. Moreover, a high percentage of epileptic patients are drug resistant; in their case, neurosurgery or neurostimulation are necessary. Therefore, the major goal of epilepsy research is to discover new therapies which are either capable of curing epilepsy without side effects or preventing recurrent seizures in drug-resistant patients. Neuroengineering provides new approaches by using novel strategies and technologies to find better solutions to cure epileptic patients at risk.

As a demonstration of a novel experimental protocol in an acute mouse model of epilepsy, a direct in situ electrophoretic drug delivery system is used. Namely, a neural probe incorporating a microfluidic ion pump (µFIP) for on-demand drug delivery and simultaneous recording of local neural activity is implanted and demonstrated to be capable of controlling 4-aminopyridine-induced (4AP-induced) seizure-like event (SLE) activity. The γ-aminobutyric acid (GABA) concentration is kept in the physiological range by the precise control of GABA delivery to reach an antiepileptic effect in the seizure focus but not to cause overinhibition-induced rebound bursts. The method allows both the detection of pathological activity and intervention to stop seizures by delivering inhibitory neurotransmitters directly to the epileptic focus with precise spatiotemporal control.

As a result of the developments to the experimental method, SLEs can be induced in a highly localized manner that allows seizure control by the precisely tuned GABA delivery at the seizure onset.

Introduction

Epilepsy is the fourth most common neurological disorder: about 1% of the population suffers from epilepsy, and about one-third of the affected have recurrent seizures. In most cases, seizures can be controlled with medication. However, drug treatment needs to be set for every patient individually, where proper dosing can take years to find^1,2. Additionally, most of the medication has serious side effects that reduce the quality of life^3,4,5,6,7. Fi....

Protocol

All experimental procedures were performed according to the ethical guidelines of the Institut de Neurosciences des Systèmes and approved by the local Ethical Committees and Veterinary Offices.

NOTE: Seventeen adult male OF1 mice were used for the experiments. Mice were entrained to a 12 h light/dark cycle with food and water available ad libitum.

1. Anesthesia

1. Inject intraperitoneally a mixture of ketamine and xylazine (100 mg/kg body weight and 10 mg/kg body weight, respectively) to anesthetize the animal.
2. Check the level of anesthesia by observing th....

Results

Using the procedure presented here with a 4AP epilepsy model in anesthetized mice, control of epileptic seizures can be achieved in the epileptic focus. The precise localization of the implants (Figure 2) helped to record hippocampal local field potentials (LFPs, Figure 4), to induce small hippocampal seizures and to deliver GABA at the seizure onset. The localization of the implants was verified after each experiment by post hoc.......

Discussion

By developing a new experimental protocol in an acute mouse model of epilepsy, SLEs could be successfully controlled with the help of a µFIP implanted in the epileptic focus. Thanks to its capability to deliver GABA with temporal and spatial precision, 4AP-induced SLEs were controlled at the onset of the seizures. Treatment of epilepsy is theoretically possible if the control of the neural network discharges is achieved at the place of the seizure start. The presented protocol proved this possible if the localizatio.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
4AP	Sigma	275875
Alexa Fluor 488	Abcam	ab15007
Amplifier	Neuralynx, Montana, USA	Digital Lynx 4SX
Amplifier	Ampliplex	KJE-1001
Atlas Stereotaxique	Allen Atlas	978-0470054086
Borosilica glass pipette	Sutter	BF120-69-15
Brain Matrix	WPI	RBMA-200C
Bone trimmer	FST	16109-14
Confocal microscope	Zeiss	LSM 510
Connector	INSTECH	SC20/15
Coton tige	Monoprix	EMD 6107OD
Cover slip	Menzel-Glass	15747592
DiI Stain	Thermo Fisher	D282
DMSO	Sigma	11412-11
Drill	FOREDOM	K1070
Forceps	F.S.T.	11412-11
GABA	Sigma	A2129
GFAP Monoclonal Antibody	Thermofisher	53-9892-80
GOPS	Sigma	440167-100M
Hamilton seringe	Hamilton	80330
Headscrew	Component Supply	TX00-2FH
Heating pad	Harvard apparatus	341446
Injection Pump	WPI	UMP3-3
Keithley	Tektoronix	216A
Ketamine	Renaudin	5787419
Magnetic holder	Supertech Instruments	MH-1
Mice	Charles River	612
Motoric manipulator	Scientifica, UK	IVM
Na2HPO4	Sigma	255793
NaH2PO4	Sigma	7558807
NeuroTrace DiI	Thermofisher	N22880
Paper towel	KIMBERLY CLARK	7552000
PB	Sigma	P4417
PEDOT:PSS	CLEVIOS	81076212
PFA	Acros Organic	30525-89-4
Rectal temperature probe	Harvard apparatus	521591
Ropivacaine	KABI	1260216
Saline	Sigma	7982
Scalpel	F.S.T	AUST R195806
Seringue	BD Medical	324826
Serrefine clamp	F.S.T	18050-28	4 is recommended
Silicon probe	NeuroNexus, Michigan, USA	A2x16-10mm-50-500-177 or A1x16-5mm-150-703
Stereotoxic frame	Stoelting	51733U
Superfrost Slide	ThermoScientific	J38000AMNZ
Tubing	INSTECH	LS20
Vaseline	Laboratoire Gilbert	3518646126611
Vectashield DAPI	Vector Laboratories, California, USA	H-1200-10
Vibratome, Leica VT1200S	Leica Microsystems	1491200S001
Xylazine	Bayer	4007221032311
Silicon probe	Neuromicrosystems Ltd	A1x32_dbl_5.0_50_0_176_50