Osteoarthritis Pain Model Induced by Intra-Articular Injection of Mono-Iodoacetate in Rats

Summary

This study describes the method of intra-articular injection of mono-iodoacetate in rats and discusses the resulting pain-related behaviors and histopathological changes, which provide references for future applications.

Abstract

The current animal models of osteoarthritis (OA) can be divided into spontaneous models and induced models, both of which aim to simulate the pathophysiological changes of human OA. However, as the main symptom in the late stage of OA, pain affects the patients' daily life, and there are not many available models. The mono-iodoacetate (MIA)-induced model is the most widely used OA pain model, mainly used in rodents. MIA is an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, which causes chondrocyte death, cartilage degeneration, osteophyte, and measurable changes in animal behavior. Besides, expression changes of matrix metalloproteinase (MMP) and pro-inflammatory cytokines (IL1 β and TNF α) can be detected in the MIA-induced model. Those changes are consistent with OA pathophysiological conditions in humans, indicating that MIA can induce a measurable and successful OA pain model. This study aims to describe the methodology of intra-articular injection of MIA in rats and discuss the resulting pain-related behaviors and histopathological changes.

Introduction

Osteoarthritis (OA) is the most common joint disease in the world, affecting an estimated 10-12% populations in adults¹. The most generally involved joint is the knee, and OA has a higher incidence in older adults, especially women². As a chronic disease, OA develops progressively over decades into joint failure with symptoms such as cartilage loss, synovial inflammation, osteophytosis, decreased function, and chronic pain³. According to the World Health Organization (WHO), OA is the fourth most prevalent disease in females and the eighth most prevalent disease in males. By 2020, OA may become the....

Protocol

Procedures involving animal subjects have been approved by the Medical Norms and Ethics Committee of Zhejiang Chinese Medical University and are in accordance with the China legislation on the use and care of laboratory animals.

1. Intra-articular injection of mono-iodoacetate in the knee

1. After one-week of acclimation, randomly and equally divide 40 male Sprague-Dawley rats weighing 180−200 g (4−5 weeks old) into four groups (n = 10 rats/group).
   NOTE: Rats in the control group will be intra-articularly injected with 50 µL of saline, while rats in the experimental groups will be treated with 0.5, 1.5 or 3 ....

Results

With this methodology, we established an OA pain model in the rat and detected the resulting changes. MWT and TWL reflected mechanical allodynia and thermal hyperalgesia, respectively. As shown in Figure 1, MIA induced mechanical allodynia and thermal hyperalgesia present in a dose-dependent manner. Remarkably, the decrease of MWT reached a peak from 21 days to 28 days, and then rebounded, suggesting that joint repair may occur at this stage, but MWT of 3 mg MIA group was still at a low leve.......

Discussion

The rat model of OA induced by MIA is a well-established, widely used model. Intra-articular injection of MIA initially causes severe and acute inflammation, which gives rise to the longer and degenerative phase of OA^17,18. In this research, we measured nociceptive sensitivity by MWT and TWL, and assessed gait alterations with an imaging system. Previous reports found that the injection of MIA could raise the sensitivity of afferent knee joint fibers leading to n.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Anti-Collagen II antibody	Abcam(UK)	34712	Primary antibody for immunohistochemistry (IHC)
Anti-Collagen X (Col10) antibody	Abcam(UK)	49945	Primary antibody for IHC
DigiGait Imaging System	Mouse Specifics (Boston, MA, USA)		Equipment for gait patterns analyses
Eosin	Sigma-Aldrich	861006	The dye for HE staining
Fast Green FCF	Sigma-Aldrich	F7252	The dye for SO staining
Goat anti-mouse antibody	ZSGQ-BIO (Beijing, China)	PV-9002	Secondary antibody for IHC
Goat anti-rabbit antibody	ZSGQ-BIO (Beijing, China)	PV-9001	Secondary antibody for IHC
Hematoxylin	Sigma-Aldrich	H3163	The dye for HE staining
MIA	Sigma-Aldrich	I4386-10G	powder
MMP13	Cell Signaling Technology, Inc. (Danvers, MA, USA)	69926	Primary antibody for IHC
Modular tissue embedding center	Thermo Fisher Scientific (USA)	EC 350	Produce paraffin blocks.
Plantar Test apparatus	UgoBasile (Italy)	37370	Equipment for TWL assay
PrimeScript RT reagent Kit (Perfect Real Time)	TaKaRa Biotechnology Co. Ltd. (Dalian, China)	RR037A	Extracte total RNA from cultured cells
Rotary and Sliding Microtomes	Thermo Fisher Scientific (USA)	HM325	Precise paraffin sections.
Safranin-O	Sigma-Aldrich	S2255	The dye for SO staining
Tissue-Tek VIP 5 Jr	Sakura (Japan)		Vacuum Infiltration Processor