Background: Tolerance to the analgesic effects of opioids and non-steroidal anti-inflammatory drugs (NSAIDs) is a major concern for relieving pain. Thus, it is highly valuable to find new pharmacological strategies for prolonged therapeutic procedures. Biguanide-type drugs such as metformin (MET) are effective for neuroprotection and can be beneficial for addressing opioid tolerance in the treatment of chronic pain. It has been proposed that analgesic tolerance to NSAIDs is mediated by the endogenous opioid system. According to the cross-tolerance between NSAIDs, especially sodium salicylate (SS), and opiates, especially morphine, the objective of this study was to investigate whether MET administration can reduce tolerance to the anti-nociceptive effects of SS. Methods: Fifty-six male Wistar rats were used in this research (weight 200–250 g). For induction of tolerance, SS (300 mg/kg) was injected intraperitoneally for 7 days. During the examination period, animals received MET at doses of 50, 75, or 100 mg/kg for 7 days to evaluate the development of tolerance to the analgesic effect of SS.The hot plate test was used to evaluate the drugs' anti-nociceptive properties. Results: Salicylate injection significantly increased hot plate latency as compared to the control group, but the total analgesic effect of co-treatment with SS + Met50 was stronger than the SS group. Furthermore, the effect of this combination undergoes less analgesic tolerance over time. Conclusions It can be concluded that MET can reduce the analgesic tolerance that is induced by repeated intraperitoneal injections of SS in Wister rats.

Background: Tolerance to the analgesic effects of opioids and non-steroidal anti-inflammatory drugs (NSAIDs) is a major concern for relieving pain. Thus, it is highly valuable to find new pharmacological strategies for prolonged therapeutic procedures. Biguanide-type drugs such as metformin (MET) are effective for neuroprotection and can be beneficial for addressing opioid tolerance in the treatment of chronic pain. It has been proposed that analgesic tolerance to NSAIDs is mediated by the endogenous opioid system. According to the cross-tolerance between NSAIDs, especially sodium salicylate (SS), and opiates, especially morphine, the objective of this study was to investigate whether MET administration can reduce tolerance to the anti-nociceptive effects of SS. Methods: Fifty-six male Wistar rats were used in this research (weight 200–250 g). For induction of tolerance, SS (300 mg/kg) was injected intraperitoneally for 7 days. During the examination period, animals received MET at doses of 50, 75, or 100 mg/kg for 7 days to evaluate the development of tolerance to the analgesic effect of SS.The hot plate test was used to evaluate the drugs' anti-nociceptive properties. Results: Salicylate injection significantly increased hot plate latency as compared to the control group, but the total analgesic effect of co-treatment with SS + Met50 was stronger than the SS group. Furthermore, the effect of this combination undergoes less analgesic tolerance over time. Conclusions It can be concluded that MET can reduce the analgesic tolerance that is induced by repeated intraperitoneal injections of SS in Wister rats.

Background: Tolerance to the analgesic effects of opioids and non-steroidal anti-inflammatory drugs (NSAIDs) is a major concern for relieving pain. Thus, it is highly valuable to find new pharmacological strategies for prolonged therapeutic procedures. Biguanide-type drugs such as metformin (MET) are effective for neuroprotection and can be beneficial for addressing opioid tolerance in the treatment of chronic pain. It has been proposed that analgesic tolerance to NSAIDs is mediated by the endogenous opioid system. According to the cross-tolerance between NSAIDs, especially sodium salicylate (SS), and opiates, especially morphine, the objective of this study was to investigate whether MET administration can reduce tolerance to the anti-nociceptive effects of SS. Methods: Fifty-six male Wistar rats were used in this research (weight 200–250 g). For induction of tolerance, SS (300 mg/kg) was injected intraperitoneally for 7 days. During the examination period, animals received MET at doses of 50, 75, or 100 mg/kg for 7 days to evaluate the development of tolerance to the analgesic effect of SS.The hot plate test was used to evaluate the drugs' anti-nociceptive properties. Results: Salicylate injection significantly increased hot plate latency as compared to the control group, but the total analgesic effect of co-treatment with SS + Met50 was stronger than the SS group. Furthermore, the effect of this combination undergoes less analgesic tolerance over time. Conclusions It can be concluded that MET can reduce the analgesic tolerance that is induced by repeated intraperitoneal injections of SS in Wister rats.

Objective: To explore the effect of ethyl acetate gum resin extract of Boswellia serrata on lipopolysaccharide (LPS) induced inflammation and oxidative damage in hepatic and renal tissues of rats. Methods: The rats were divided into four groups: control, LPS, LPS+Boswellia serrata extracts (100 mg/kg and 200 mg/kg). LPS (1 mg/kg) and the extract (100 and 200 mg/kg, 30 min before LPS) were administered intraperitoneally for 3 weeks. The levels of liver enzymes, albumin, total protein, creatinine, blood urea nitrogen (BUN), interleukin (IL)-6, malondialdehyde (MDA), and total thiol groups and superoxide dismutase (SOD) and catalase (CAT) activities were measured. Results: The levels of liver enzymes, creatinine, and BUN, IL-6, MDA in the LPS group were markedly increased (P<0.001) while albumin, total protein, and total thiol concentration, as well as SOD and CAT activities, were decreased compared with the control group (P<0.05 or 0.01). Boswellia serrata extracts diminished the levels of liver enzymes, creatinine, BUN, IL-6, and MDA (P<0.01 and P<0.001), and elevated the concentration of total protein and total thiol and SOD and CAT activities (P<0.05 or 0.01). Conclusions: The ethyl acetate gum resin extract of Boswellia serrata reduces LPS-induced inflammatory reactions and oxidative damage, thus ameliorating hepatic and renal function.