Swallowing pain relief

Anew study shows that, in the presence of morphine, low doses of an opiate analogue can induce receptor endocytosis, thereby reducing the development of tolerance to morphine. Jennifer Whistler and colleagues at the Gallo Institute (University of California, San Francisco, CA) demonstrated that rats treated with morphine together with subanalgesic doses of a second opiate did not develop tolerance to the morphine even after seven days of treatment.

Although morphine is a favored choice for easing pain, a major drawback of its long-term use is the development of tolerance, which results in reduced analgesic effects upon long-term use. Morphine binds the μ opioid receptor (MOR), one member of the large G protein–coupled receptor family. Once bound by natural ligands such as endorphins, or several opiate drugs such as methadone, opioid receptors normally undergo desensitization via uncoupling...