Journal of Pain Research (Dec 2021)
Implantable, Programmable, and Wireless Device for Electrical Stimulation of the Dorsal Root Ganglion in Freely-Moving Rats: A Proof of Concept Study
Abstract
Ivana Vuka,1 Tihana Marciuš,1 Damir Kovačić,2 Antonio Šarolić,3 Livia Puljak,4,* Damir Sapunar1,* 1Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia; 2Laboratory for Biophysics and Medical Neuroelectronics, University of Split Faculty of Science, Split, Croatia; 3Laboratory for Applied Electromagnetics (EMLab), FESB, University of Split, Split, Croatia; 4Centre for Evidence-Based Medicine and Health Care, Catholic University of Croatia, Zagreb, Croatia*These authors contributed equally to this workCorrespondence: Damir SapunarLaboratory for Pain Research, University of Split School of Medicine, Šoltanska 2, Split, 21000, CroatiaTel +385 21-557-809Email [email protected]: This was a proof of concept study, based on systematic reviews of the efficacy and safety of the dorsal root ganglion (DRG) stimulation. The main objective was to develop an implantable, programmable, and wireless device for electrical stimulation of DRG and a methodology that can be used in translational research, especially to understand the mechanism of neuromodulation and to test new treatment modalities in animal models of pain.Methods: We developed and tested a stimulator that uses a battery-powered microelectronic circuit, to generate constant current square biphasic or monophasic pulsed waveform of variable amplitudes and duration. It is controlled by software and an external controller that allows radio frequency communication with the stimulator. The stimulator was implanted in Sprague–Dawley (SD) rats. The lead was positioned at the L5 DRG level, while the stimulator was placed in the skin pocket at the ipsilateral side. Forty-five animals were used and divided into six groups: spinal nerve ligation (SNL), chronic compression injury of the DRG (CCD), SNL + active DRG stimulation, intact control group, group with the implanted sham stimulator, and sham lead. Behavioral testing was performed on the day preceding surgery and three times postoperatively (1st, 3rd, and 7th day).Results: In animals with SNL, neurostimulation reduced pain-related behavior, tested with pinprick hyperalgesia, pinprick withdrawal test, and cold test, while the leads per se did not cause DRG compression. The rats well tolerated the stimulator. It did not hinder animal movement, and it enabled the animals to be housed under regular conditions.Conclusion: A proof-of-concept experiment with our stimulator verified the usability of the device. The stimulator enables a wide range of research applications from adjusting stimulation parameters for different pain conditions, studying new stimulation methods with different frequencies and waveforms to obtain knowledge about analgesic mechanisms of DRG stimulation.Keywords: neurostimulation, implantable stimulator, DRG, SNL, pain-related behavior
