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A common side effect of opioids is intense itching, researchers at Washington University School of Medicine in St. Louis have found a drug- nalfurafine hydrochloride, it reliefs itching by targeting opioid receptors on neurons in the spinal cord. The drug is used for alleviate itching in dialysis patients with kidney and liver disease.
The drug may be effective against many types of chronic itching that don’t respond to conventional drugs such as antihistamines. The drug targets kappa opioid receptors on neurons in the spinal cord. While other opioid receptors on the same neurons can ramp up itching, this study shows that activating the kappa receptor significantly reduces itching.
The kappa opioid receptors activate a pathway that tamps down the activity of GRPR, which our lab previously identified as the first itch gene,” said senior investigator Zhou-Feng Chen, PhD, director of the Center for the Study of Itch at Washington University School of Medicine in St. Louis. This gene relays itch signals from the spine to the brain.
Researchers studied mice treated with a substance to make them feel itchy. Others had been genetically engineered to develop chronic itching. When the researchers injected the drug directly into the spinal cords of the animals, their scratching was reduced. Half of the neurons in the spinal cord that transmit itch signals have kappa opioid receptors.
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