Title:Peripheral Anti-nociceptive and Anti-inflammatory Effect of Oleanolic Acid in a Rat Model of Osteoarthritis
Volume: 20
Issue: 3
Author(s): Israa Salman, Marc Fakhoury, Malak Fouani and Nada Lawand*
Affiliation:
- Department of Anatomy, Cell biology & Physiological Sciences; Faculty of Medicine; American University of Beirut, Beirut,Lebanon
Keywords:
Inflammation, Kaolin/carrageenan, motor coordination, nociception, oleanolic acid, osteoarthritis, pain.
Abstract:
Background: Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid with
multifarious actions. The anti-inflammatory effect it exerts when taken orally is the most
important; however, the underpinning mechanisms of such effects have not yet been fully explored.
Methods: In the present study, we evaluated the anti-inflammatory and anti-nociceptive effect of
OA by injecting it directly into the knee joint using an animal model of osteoarthritis. Behavioral
and electrophysiological studies were conducted to determine whether OA exerts a direct modulatory
effect on primary sensory afferents that can lead to a decrease in pain-related behaviors and inflammatory
responses. Rats were divided into two main groups: a pre- and a post-treatment group.
Knee joint inflammation was induced by injecting a mixture of 3% kaolin and carrageenan (K/C).
In the pre-treatment group, two different doses of OA [5 mg/ml (n=5) and 30 mg/ml (n=4); 0.1 ml
per injection] were administered into the synovial cavity of the knee joint before induction of inflammation.
In the post-treatment group, rats received only one dose [5 mg/ml (n=5)] of OA after
induction of inflammation.
Results: Results indicate that intra-articular injection of OA improves motor coordination and attenuates
nociceptive behavior and inflammatory reactions. More importantly, we observed a direct depolarizing
action of OA on articular sensory fibers, a crucial mechanism that activates descending
inhibitory pathways and controls incoming nociceptive signals to the spinal cord.
Conclusion: Overall, our findings suggest that OA can be used as a preventive and therapeutic approach
for the management of osteoarthritis.
