Assessment of Knee Hyperalgesia in Mice using Pressure Application Measurement

Summary

The protocol describes how to measure knee hyperalgesia in mice. We show examples in mouse models of acute knee pain as well as in models of osteoarthritis (OA).

Abstract

Assessment of knee hyperalgesia provides a robust assay for measuring peripheral sensitization in the knee, and represents a clinically relevant pain-dependent behavior that can be used in rodent models of arthritis. Several methods have been reported to determine the threshold for responses to knee compression in rodents. Here, we aimed to adapt existing methods to develop a standardized method for assessing knee hyperalgesia in adult mice, using a Pressure Application Measurement (PAM) device. The protocol includes detailed steps, training recommendations for new experimenters, and tips for achieving consistent results. We provide suggestions for optimal training of a new experimenter. Finally, representative outcomes are provided for both acute models of transient hyperalgesia and experimental osteoarthritis (OA) models, which are characterized by chronic pain. This method is highly sensitive to pharmacological interventions, making it suitable for evaluating the effects of mediators like cytokines and for medium-throughput drug screening assays. In summary, the described approach provides a robust and clinically relevant method for quantifying knee hyperalgesia.

Introduction

Osteoarthritis (OA), the most common form of arthritis, is characterized by progressive cartilage degradation, synovitis, bone remodeling, and osteophyte growth¹, and presents clinically as pain and loss of joint function. OA is one of the major sources of chronic pain in the world, profoundly impacting patients' lives due to reduced mobility and associated health issues such as anxiety and depression^2,3. Commonly prescribed drugs for OA pain include nonsteroidal anti-inflammatory drugs (NSAIDs), visco-supplementation, corticosteroids, and opioids, but their efficacy is limited, and....

Protocol

All experimental protocols were approved under the category E by the Rush University Institutional Animal Care and Use Committee. The protocol described is to assess knee hyperalgesia in the right knee in response to a mechanical stimulus in adult C57BL/6 mice (10 weeks- 2 years of age) of either sex. To measure knee hyperalgesia in the left knee, switch hands.

1. Setting up the Pressure Application Measurement (PAM) device

1. Connect one cable from the PAM device to the computer and the second cable from the PAM device to the force transducer.
2. Turn on the computer and start the PAM software. Set the maxi....

Results

Time course of knee hyperalgesia in a model of acute knee pain
All results shown have been previously reported by our group, and we refer to¹⁰for a detailed description. The first example shows a model for inducing acute, transient knee hyperalgesia. In this experiment, we injected Pam3CSK4, a synthetic toll-like receptor 2 (TLR2) ligand (1 µg or 3 µg, dissolved in sterile water) at 5 µL, into the knee cavity of 10-week-old naïve male C57BL/6 mice, using a Hamilton syringe wit.......

Discussion

Measurement of knee hyperalgesia in mice offers a relatively fast and straightforward means of assessing knee hyperalgesia associated with experimental arthritis. As can be observed from the representative results shown, the assay can detect acute onset and transient hyperalgesia (Figure 2A). We have reported this behavior in response to several mediators injected into the knee joint, including an aggrecan fragment¹⁰, a neurotrophin, nerve growth factor (NGF)

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
C-C chemokine 2 receptor antagonist (CCR2RA)	Tocris	RS 504393
computer (any type)			windows 7 minimum
Lidocaine	Sigma	L5647
Pressure Application Measurement (P.A.M)	Ugo Basile	38500	included transducer, computer, cables
sandwich bag	whole food market	6-1/2 x 5-7/8	cover the transducer
toll-like receptor 2 ligand Pam3CSK4	invitrogen	tlrl-pms