A Thermal Injury Model by Monopolar Radiofrequency on Sciatic Nerve in Mice

Summary

This study applied radiofrequency systems to the sciatic nerves of mice, establishing a radiofrequency ablation model of thermal nerve injury. This approach resolves issues of controllability in mice peripheral nerve thermal injury models, providing a practical modeling method for research on nerve injury repair and neuropathic pain.

Abstract

Peripheral nerve injury often results in neuropathic pain and triggers nerve repair processes. Whilst controllable physical injury models are now well-established, existing thermal injury models remain exploratory and exhibit poor controllability. In clinical practice, radiofrequency ablation (RFA) systems are frequently employed to induce thermal injury to tissues and nerves. RFA is a therapeutic modality that has been demonstrated to effectively block pain transmission by inducing thermal damage to nerves. The extent of the ablation can be modified by adjusting specific parameters, as well as the degree of numbness and motor dysfunction in the affected nerve distribution area. This study used a monopolar radiofrequency system to create a stable, controllable nerve injury model in the sciatic nerve of mice by applying 75°C for 30 s. A significant increase in mechanical withdrawal threshold (MWT) was observed from days 7–14 post-surgery, with recovery occurring by day 28. This research addresses the current gap in RFA nerve injury models, replicates the nerve damage observed clinically after RFA procedures, and provides a methodological framework for subsequent studies on RFA-induced nerve injury.

Introduction

Neuropathic pain presents ongoing challenges in clinical management, as its pain mechanisms continue to be investigated. To study the molecular and cellular mechanisms of neuropathic pain, spinal nerve ligation (SNL)¹, chronic constriction injury (CCI)², partial sciatic nerve ligation (pSNL)³, and sciatic nerve transection (SNT)⁴, and spared nerve injury (SNI)⁵ have been successfully used in rodents to simulate peripheral physical nerve injury. To enhance the controllability and stability of the model, previous studies proposed improvements, such as ....

Protocol

Animal experiments were approved by the Animal Ethics Committee of the Experimental Animal Center, Xuanwu Hospital, Capital Medical University, and were conducted in accordance with the NIH Guide for the Care and Use of Laboratory Animals¹⁴. Adult male C57BL/6 mice (8–10 weeks old, 20–25 g) were group-housed (4–5 per cage) under controlled environmental conditions (22 ± 2 °C, 50%–60% humidity, 12 h light/dark cycle with lights on at 07:00) with ad libitum access to standard rodent chow and water. All behavioral assessments were performed during the light phase between 08:00 and 12:00. Details of the reagents, s....

Results

Successful model establishment was confirmed by both intraoperative and postoperative indicators. At the completion of RFA (75 °C, 30 s), mild adhesion between the RFA needle tip and the sciatic nerve was observed upon withdrawal. This adhesion results from localized protein denaturation and coagulation at the contact site and suggests appropriate thermal energy delivery along with direct nerve contact. Absence of adhesion may indicate needle displacement during the procedure, leading to inconsistent or suboptimal nerve .......

Discussion

With the rapid development of minimally invasive surgery, radiofrequency technology has become increasingly widespread^6,7,18. As radiofrequency technology has expanded in clinical practice, related research has facilitated its broader adoption. However, the effects of radiofrequency current on tissue require further investigation, especially after radiofrequency technology is applied to the treatment of neuropathic pain, and the.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
4-0 suture	Jinhuan Medical	C412	Close the skin
6-0 suture	Jinhuan Medical	KCR631	Close the muscular layer
Alexa Fluor 488 secondary antibody	Invitrogen	A-11008	Secondary antibody
ATF3 rabbit polyclonal antibody	Novus Biologicals	NBP1-85816	Polyclonal antibody
Curved fine forceps	Beyotime Biotechnology	FS031	Cut muscle and fascia
DAPI antifade mounting medium	Beyotime Biotechnology	P0131	Antifade medium
Glass minute hand	Yuyan Instruments	BLFZ10	Lift up the nerve
GraphPad Prism	Graphpad Software, LLC	version 9.0	Output data images
Micro Scissors	Beyotime Biotechnology	FS217	Cut skin incision
Modified Ringer’s solution	Self-prepared	N/A	Sodium lactate 3.10 g/L; NaCl 6.00 g/L; KCl 0.30 g/L; CaCl2·2H2O 0.20 g/L
Needle Holder	Yuyan Instruments	Y32010	Hold needles
QuickBlock blocking solution	Beyotime Biotechnology	P0260	Blocking reagent for immunofluorescence
Radiofrequency therapeutic device	Cosman Medical	RFG-1A	Radiofrequency system
radiofrequency thermo-coagulation electrode trocar	Cosman Medical	TCD-10	Insulated RF needle
Sodium Lactate Ringer's Injection	Sichuan Kelun Pharmaceutical Co., Ltd	86902180001566	ionic liquid to reduce the resitance
SPSS Statistics	IBM Corp	version 27.0	Statistical analysis software
Straight fine forceps	Beyotime Biotechnology	FS027	Cut muscle and fascia
Von Frey fiber wire	Danmic Global	Aesthesio Semmes-Weinstein	Behaviour test