*Review* **Understanding the Molecular Mechanisms Underlying the Pathogenesis of Arthritis Pain Using Animal Models**

**Jeong-Im Hong 1,2,**†**, In Young Park 1,2,**† **and Hyun Ah Kim 1,2,\***


Received: 20 November 2019; Accepted: 9 January 2020; Published: 14 January 2020

**Abstract:** Arthritis, including osteoarthritis (OA) and rheumatoid arthritis (RA), is the leading cause of years lived with disability (YLD) worldwide. Although pain is the cardinal symptom of arthritis, which is directly related to function and quality of life, the elucidation of the mechanism underlying the pathogenesis of pain in arthritis has lagged behind other areas, such as inflammation control and regulation of autoimmunity. The lack of therapeutics for optimal pain management is partially responsible for the current epidemic of opioid and narcotic abuse. Recent advances in animal experimentation and molecular biology have led to significant progress in our understanding of arthritis pain. Despite the inherent problems in the extrapolation of data gained from animal pain studies to arthritis in human patients, the critical assessment of molecular mediators and translational studies would help to define the relevance of novel therapeutic targets for the treatment of arthritis pain. This review discusses biological and molecular mechanisms underlying the pathogenesis of arthritis pain determined in animal models of OA and RA, along with the methodologies used.

**Keywords:** osteoarthritis; rheumatoid arthritis; animal model; pain
