A Chinese scientist and his team have recently uncovered a previously uncharacterized neural pathway that holds promise for treating opioid withdrawal more effectively by suppressing urges at their origin within the brain.

“Studying the neural mechanisms underlying withdrawal symptoms will provide new insights for the development of novel drugs or therapeutic strategies to prevent continuous opioid use,” said Xiaoke Chen, the principal investigator of the research, which was published in the current issue of Nature.

“Prescription opioid abuse is the fastest growing drug problem in the United States. Now, deaths from overdose of opioid pain relievers exceed those from all illegal drugs,” said Chen, an assistant professor of biology at Stanford.

The death rate from drug overdoses is jumping to an average of 15 per 100,000 in 2014 from nine per 100,000 in 2003. During 2014, a total of 47,055 people died of drug overdoses nationally, the equivalent of about 125 Americans every day, according to a January report by the Centers for Disease Control and Prevention.

Opioids, including heroin and fentanyl, a painkiller 100 times more powerful than morphine, were involved in more than 61 percent of overdose deaths in 2014.

Opioids’ potent euphoric effects and excessive withdrawal symptoms make them the most commonly abused prescription drugs. Both negative physical withdrawal symptoms, such as nausea, diarrhea, vomiting and pain, as well as emotional symptoms, such as anxiety, depression and irritability are extremely unpleasant to dependent individuals, Chen said.

“The desire to avoid these unpleasant withdrawal symptoms is thought to be an important motivator to continuous drug use,” Chen said.

The researchers have successfully manipulated the brains of morphine-addicted mice and allowed them to overcome withdrawal symptoms.

“Chronic morphine use altered the neural transmission in this pathway, and restoring its normal activity in this pathway can completely block the expression of withdrawal symptoms in morphine-dependent mice,” Chen said.

In their research, they used fluorescent proteins to illuminate brain centers and view the pathways that connect them. The experiment highlighted a particularly clear link between the nucleus accumbens (NAc) and a small group of cells in the paraventricular nucleus of the thalamus (PVT).

“Morphine can act on all neurons that express the mu-opioid receptor, which is wildly expressed in many regions in the brain,” said Chen. “Here, we only manipulated one single pathway and eliminated the withdrawal behavior suggested that the pathological change at the PVT to NAc pathway is the origin of the withdrawal symptoms.

liazhu@chinadailyusa.com