Opiates are drugs made of analgesic alkaloid compounds found naturally in the opium poppy plant, which include morphine, codeine, and thebaine. They are considered drugs of high abuse potential, since produce a sense of euphoria that is highly addictive. Abrupt cessation or reduction of prolonged opiate usage cause opiate withdrawal symptoms like anxiety, sweeting, diarrhea, nausea, vomiting, insomnia, muscle aches and runny nose.
Stanford researchers, headed by assistant professor of biology Xiaoke Chen, focused their attention in the nucleus accumbens. This group of neurons in the hypothalamus has an important role in addiction since they are involved with the cognitive processing of motivation, aversion, reward, pleasure, and reinforcement learning.
For the research, published in Nature, Chen’s team used fluorescent proteins in opiate-addicted mice to identify a pathway between their paraventricular nucleus of the thalamus (PVT), which is another neuronal nucleus that is considered part of the drug-seeking circuitry, and the nucleus accumbens.
Once they identified the PVT- nucleus accumbens pathway, they turn the neurons in this pathway off by using a method called optogenetics, in which light-sensitive molecules are introduced and then hit with light from an optical fiber.
The results showed that this method erased the effect of the drug, rehabilitating the pathway to its original strength. These results may suggest that reprogramming the circuit may help for treating opiate addiction in humans.
“Most research that studies drug addiction is focused on the reward pathway because that is the reason you start to take drugs, but people who really get addicted also take drugs to get rid of the withdrawal effect. This is especially important in opiate addiction,” said Chen.
Chen’s findings are also promising for the development of treatments for people with aversive response to stimuli, including those with drug addiction, anxiety and depression.
Source: Stanford Medicine