The role of adrenergic receptors and pain: The good, the bad, and the unknown

Adrenergic receptors appear to play an important role in the modulation of pain. There is now abundant evidence that activation of adrenergic receptors can, in certain circumstances, generate impressive analgesic effects. However, under other circumstances, adrenergic receptors can contribute to chronic neuropathic pain and hyperalgesia. This review will focus on the beneficial effects of adrenergic pain modulation, and the circumstances when this modulation appears to magnify pain. This review will also address controversies surrounding how these two opposing processes occur via the same mediators.