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A Modified Inflammatory Pain Model to Study the Analgesic Effect in Mice
Published on: November 15, 2024
COX-2 expression and function in the hyperalgesic response to paw inflammation in mice
Naveen K Jain1, Tomo-o Ishikawa, Igor Spigelman
1Department of Biological Chemistry, UCLA School of Medicine, 341 Boyer Hall, University of California, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.
Prostaglandins, Leukotrienes, and Essential Fatty Acids
|October 3, 2008
Summary
Cyclooxygenase-2 (COX-2) does not mediate primary hyperalgesia in a mouse paw inflammation model. However, COX-2 plays a significant role in the central mechanisms of this pain response.
Area of Science:
- Neuroscience
- Pharmacology
- Immunology
Background:
- Peripheral inflammation and edema often lead to primary and secondary hyperalgesia.
- Cyclooxygenase-2 (COX-2)-mediated prostanoid production is a key area of interest in understanding hyperalgesia.
- A murine foot-pad inflammation model was developed to study COX-2's role in hyperalgesia.
Purpose of the Study:
- To investigate the role of COX-2 in mediating primary and central hyperalgesia in a zymosan-induced inflammation model.
- To differentiate the contributions of COX-2 to peripheral versus central pain mechanisms.
Main Methods:
- Induction of inflammation and edema in the mouse hindpaw using zymosan injection.
- Assessment of primary hyperalgesia via hindpaw withdrawal latency to thermal stimuli.
- Evaluation of central hyperalgesia using tail flick latency to heat stimulus.
- Pharmacological inhibition of COX-2 using parecoxib.
- Genetic analysis using cyclooxygenase-2 knockout (Cox-2-/-) mice.
Main Results:
- Zymosan induced edema and increased COX-2 expression in the paw, spinal cord, and brain.
- Primary hyperalgesia was not inhibited by systemic COX-2 inhibition or absent in Cox-2-/- mice.
- Central hyperalgesia was reduced by parecoxib and significantly diminished in Cox-2-/- mice compared to controls.
- Central hyperalgesia resolved faster in Cox-2-/- mice.
Conclusions:
- COX-2 function is not essential for the development of primary hyperalgesia in this zymosan-induced paw inflammation model.
- COX-2 plays a critical role in the central component of hyperalgesia in this inflammatory pain model.
- These findings highlight distinct roles for COX-2 in peripheral and central pain processing during inflammation.
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