Does dipyrone produce anxiolytic-like effects in mice?

Purpose: Paracetamol has been shown to exert anxiolytic-like effects mediated by endocannabinoids via cannabinoid CB1 receptors. Dipyrone is an analgesic with similar effects to paracetamol rather than non-steroidal anti-inflammatory drugs. Involvement of central structures to its effects are long under debate, whereas recent findings suggesting contribution of cannabinoid CB1 receptors to its antinociceptive effect support this argument. Taken together, the purpose of this study was to investigate whether dipyrone possesses anxiolytic-like behavior; contribution of cannabinoid CB1 and CB2 receptors and TRPV1 receptors will be determined in case of observing any effect of dipyrone in anxiety tests. Materials and Methods: Balb-c mice effects of dipyrone (150, 300, 600 mg/kg, i.p.) were assessed in three-chamber social interaction, open-field, elevated plus-maze and rota rod tests. The cannabinoid CB1 antagonist AM251 (1 mg/kg i.p.), the CB2 antagonist SR 144528 (1 mg/kg i.p.) and the TRPV1 antagonist capsazepine (3 mg/kg i.p.) were going to be administered before dipyrone injections if any effect of dipyrone occurs. Results: Dipyrone had no effect at any dose in behavioral tests (three-chamber social interaction, open-field, elevated plus-maze and rota rod tests). Therefore, dipyrone is not tested together with the cannabinoid CB1 and CB2 antagonists and the TRPV1 receptor antagonist. Conclusion: Unlike paracetamol, dipyrone did not possess anxiolytic-like effects in mice. Discrepancies in experimental models and methodologies may be the reason of our results