European journal of pharmacology
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Comparative Study
Hyperbaric oxygen treatment reduces carrageenan-induced acute inflammation in rats.
The present study was designed to assess the anti-inflammatory activity of hyperbaric oxygen treatment by comparing it with that of diclofenac, a nonsteroidal anti-inflammatory drug, and also to investigate whether hyperbaric oxygen treatment enhances the anti-inflammatory effect of diclofenac in carrageenan-induced paw edema which is commonly employed as an acute inflammation model in rats. Hyperbaric oxygen treatment and diclofenac (20 mg/kg) markedly reduced the carrageenan-induced paw edema in rats. In other words, they displayed anti-inflammatory activity. On the other hand, hyperbaric oxygen treatment did not consistently modify the anti-inflammatory effect of diclofenac in this model.
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This study was designed to determine (1) whether chronic amitriptyline administration was effective in alleviating symptoms of neuropathic pain in a rat model of spinal nerve injury, and (2) whether the effect of amitriptyline involved manipulation of endogenous adenosine, by determining the effect of caffeine, a non-selective adenosine A(1) and A(2) receptor antagonist, on its actions. Nerve injury was produced by unilateral spinal nerve ligation of the fifth and sixth lumbar nerves distal to the dorsal root ganglion, and this resulted in stimulus-evoked thermal hyperalgesia and static tactile mechanical allodynia. Animals received pre- and post-surgical intraperitoneal doses of amitriptyline (10 mg/kg) and caffeine (7.5 mg/kg), alone or in combination, and following surgery, were administered amitriptyline (15-18 mg/kg/day) and caffeine (6-8 mg/kg/day), alone or in combination, in the drinking water. ⋯ The results of this study indicate that chronic administration of amitriptyline is effective in alleviating thermal hyperalgesia, but not static tactile allodynia, in the hindpaw ipsilateral to nerve injury, and the block of this effect by caffeine suggests that this effect is partially achieved through manipulation of endogenous adenosine systems. Additionally, chronic amitriptyline administration induces contralateral hyperaesthetic responses that are augmented by caffeine. Both the symptom-specific effect, and adenosine involvement in amitriptyline action may be important considerations governing its use in neuropathic pain.