Comparative Effect of Antidepressants (Duloxetine) and NSAID (Dexibuprofen) in a New Rat Model of Chronic Pain Induced Depression Associated with Monosodium Iodo Acetate (MIA) Induced Osteoarthritis in Rats

Objective: To evaluate the role of anti-depressants (Duloxetine) and NSAID (Dexibuprofen) in a new rat model of chronic induced depression.
Methods: Twenty four male wistar rats were divided into 4 groups of 6 animals each. Group I to IV served as vehicle control, osteoarthritis (OA) control, duloxetine and dexibuprofen treated groups respectively. Group I received intra-articular Injection of 50 µl of 0.9% normal saline, and Group II to IV received 50 µl MIA, and the treatment of drugs started on the same day. The animals will be monitored for OA parameters and/or depression on pre-dose day (day 0) and on day 1, 3, 5, 7, 11, 14, 18, 21 and 28 th day.
Results and Discussion: In MIA treated group, the rise in knee inflammation is maximum on day 3 (12.31±0.85 mm; p<0.001) and reduced near to normal on day 7 (9.26±0.57 mm; p<0.001). Dexibuprofen and duloxetine decreased the inflammation from day 3, and the decrease is comparatively better in dexibuprofen group. Also, dexibuprofen increased vocalization threshold of knee compression force for 7 days and decreased thereafter, whereas duloxetine has no effect for first 7 days and increased thereafter. Duloxetine was significantly (p<0.001) effective on neuropathic pain (Punctate allodynia, mechanical gripstrength, threshold angle of knee extension) and depression (forced swim test and locomotor activity) compared to dexibuprofen.
Conclusion: The present study has shown that dexibuprofen has the potential in the initial phase of chronic OA and duloxetine in the later stage, where neuropathic and depressive component dominates.