Effect of tramadol on immune responses and nociceptive thresholds in a rat model of incisional pain

Abstract

Abstract:Objective: To evaluate the effects of tramadol on the proinflammatory responses in a rat model of incisional pain by investigating its effects on nociceptive thresholds and serum interleukin-6 (IL-6) and IL-2 levels. Methods: Forty-two male Sprague-Dawley (SD) rats scheduled for plantar incision were randomly divided into 7 groups (n=6 in each group). Rats in Group 1 receiving general anesthesia with no incision were served as control; At 30 min before skin incision, Groups 2~5 were given 5 ml normal saline or 1, 10, and 20 mg/kg tramadol, respectively, intraperitoneally (i.p.); Group 6 received 10 mg/kg tramadol after operation; Group 7 received 10 mg/kg tramadol before incision, followed by 200 μg/kg naloxone after operation. Mechanical allodynia was measured by electronic von Frey filament to evaluate the nociceptive thresholds 1 h before incision, and 1 h and 2 h after operation. Serum IL-6 and IL-2 levels were measured by enzyme-linked immunosorbent assay (ELISA) 2 h after operation. Results: Mechanical thresholds decreased significantly and serum IL-6 level increased significantly after operation in Group 2 compared with control (P<0.01), and these changes were reversed respectively by tramadol in a dose-dependent manner (P<0.05 and P<0.01, respectively). IL-2 level remained unchanged after operation in Group 2, but decreased in Group 3 (P<0.05), then gradually returned to the normal level in Groups 4 and 5. The intraperitoneally injected tramadol (10 and 20 mg/kg) produced a potent and dose-dependent antinocicptive effect on the lesioned paw. The antinocicptive effects of tramadol were partially antagonized by naloxone (200 μg/kg), suggesting an additional non-opioid mechanism. Conclusion: The results suggest that tramadol could be a good choice for the treatment of pain under the conditions that immunosuppression may be particularly contraindicated.

Reproductive Toxicity and Biomarker Response to a Daily Dose of Tramadol in Male Albino Rats (Rattus norvegicus)

“…The non-significant (P>0.05) effect of treatment of rats with tramadol also indicate that there were no change in the oxygen-carrying capacity of the blood and the amount of oxygen delivered to the tissues since RBC and haemoglobin (Hb) are very important in transferring respiratory gases. This is contrary to the result gotten by [15] which showed a marked decrease in erythrocytic variables in rats. This difference may be because in the study, tramadol was injected into the blood stream directly.…”

A Prospective Study to Assess the Levels of Interleukin-6 Following Administration of Diclofenac, Ketorolac and Tramadol After Surgical Removal of Lower Third Molars

“…In a study conducted on rats Yong-Min Liu et al [6] concluded that tramadol was associated with decreased IL-6 and unchanged IL-2 levels, thus suggesting that tramadol may supress the inflammation induced by incision and has beneficial role in the modulation of IL-2 associated cell mediated immunity.…”

Effects of tramadol and o-desmethyltramadol on canine innate immune system function

“…In contrast, low dosages of tramadol down‐regulated IL‐2 production while higher dosages had no effect (Liu et al. ). The mechanisms underlying the differential immunomodulatory effects are unclear.…”

“…) and improves immune function in rats by modulating inflammation through leukocyte cytokine release (Liu et al. ). Although immunomodulation by opioids has been studied in rodent models and humans, no studies to date have investigated the effect of tramadol on the innate immune system in dogs.…”