Preventive and therapeutic effects of a beta adrenoreceptor agonist, dobutamine, in carrageenan-induced inflammatory nociception in rats.

We hypothesized that locally administrated β-adrenoreceptor agonist can modulate the inflammatory nociceptive parameters in carrageenan (CG)-induced peripheral inflammatory pain. This study was therefore aimed to assess the preventive and therapeutic effects of a β-agonist, dobutamine, by investigating its pretreatment and posttreatment actions on the inflammation-induced hypersensitivities (thermal hyperalgesia, mechanical allodynia) to cutaneous stimulation, edema, and several biochemical oxidant and anti-oxidant parameters in a rat model of CG-induced hind paw inflammation. Effects of dobutamine were compared with those of esmolol, a β-adrenoreceptor antagonist. CG injection to healthy rats lowered the thermal latencies (from 10.1 ± 0.2 to 4.9 ± 0.1 s) and mechanical thresholds (from 32.9 ± 0.5 to 18.9 ± 1.3 g) and caused the hyperalgesia and allodynia. In CG-induced inflamed paws, while intraplantar esmolol treatment (1 mg) produced significant decreases in latencies (4.1 ± 0.1 s) and thresholds (15.2 ± 2.4 g), dobutamine (1 mg) increased the latencies (11.3 ± 0.5 s) and thresholds (26.3 ± 2.8 g). In contrast to esmolol, dobutamine increased the superoxide dismutase level and decreased the myeloperoxidase, malondialdehyde, and nitric oxide levels in CG-induced inflamed paws. The present results can reveal that β-adrenoreceptors may play a role in inflammatory nociceptive processes, and locally treated β-adrenoreceptor agonists such as dobutamine can be a preferable, appropriate choice for the management of inflammatory nociception due to their preventive and therapeutic effects on CG-induced peripheral inflammatory nociception.