Purpose: Beta (Î²-)-adrenergic receptor antagonists, such as metoprolol, are often used to avoid circulatory complications during anesthesia for their antihypertensive and anti-tachycardia effects in patients with cardiovascular diseases. Although a few previous studies have been reported to exert antinociceptive and anesthetic effects of these drugs, knowledge about their action mechanisms in nociceptive process including pain perception is limited. This study therefore designed to identify the roles underlying the probable anti or hyper nociceptive effects of metoprolol, a Î²-adrenergic receptor antagonist. In addition, effects of metoprolol were compared the dobutamin, a Î²-adrenergic agonist.
Material and Methods: To investigate the effects of Î²-adrenergic receptor blocker, metoprolol, sensor functions using thermal plantar test (hyperalgesia) and dynamic plantar aesthesiometer (allodynia) techniques were examined in the rats after local (intraplantar) injection to paws.
Results: Metoprolol, an antagonist, significantly decreased the thermal latency and mechanical thresholds with dose and time dependent manner. However, dobutamine, an agonist, enhanced the latency and thresholds dose and time dependent.
Conclusions: This results suggest that ın contrast to dobutamine, locally treated metoprolol may cause hyperalgesic and allodynic actions. In addition, our results can demonstrate that peripheral Î²-adrenergic receptors can play important roles in nociceptive process.
Metoprolol, Intraplantar, Hyperalgesia, Allodynia, rat