Behavioural pharmacology
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Behavioural pharmacology · Apr 2015
Postinjury treatment with magnesium sulfate attenuates neuropathic pains following spinal cord injury in male rats.
Spinal cord injury (SCI) has a number of severe and disabling consequences including chronic pain. Approximately 40% of patients experience neuropathic pain, which appears to be persistent. Previous studies have demonstrated the neuroprotective effects of magnesium sulfate (MgSO4). ⋯ Tail-flick latency and acetone drop test scores were evaluated before surgery and once a week for 4 weeks after surgery. Rats in groups SCI+Mg300 and SCI+Mg600 showed significantly higher mean tail-flick latencies and lower mean scores in the acetone test compared with those in the SCI+veh group 4 weeks after surgery (P<0.05). These findings revealed that systemic single-dose administration of MgSO4 can attenuate thermal hyperalgesia and cold allodynia induced by SCI in rats.
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Tapentadol, a new analgesic drug with a dual mechanism of action (μ-opioid receptor agonism and norepinephrine reuptake inhibition), is indicated for the treatment of moderate to severe acute and chronic pain. In this paper, the possible additional involvement of the nitric oxide synthase (NOS) system in the antinociceptive activity of tapentadol was investigated using an unspecific inhibitor of NOS, L-NOArg, a relatively specific inhibitor of neuronal NOS, 7-NI, a relatively selective inhibitor of inducible NOS, L-NIL, and a potent inhibitor of endothelial NOS, L-NIO. ⋯ All four NOS inhibitors, administered intraperitoneally in the dose range 0.1-10 mg/kg, potentiated the analgesic action of tapentadol at a low dose of 2 mg/kg in both models of pain. We conclude that NOS systems participate in tapentadol analgesia.