January 3, 2013
Opiate-Like Substance Released Using Electric Brain Stimulation
April Flowers for redOrbit.com - Your Universe Online
A research team from the University of Michigan used electricity on certain regions in the brain of a patient with chronic, severe facial pain to release an opiate-like substance that's considered one of the body´s most powerful painkillers.
The findings, published in Frontiers in Psychiatry, expanded on a previous study with Harvard University and the City University of New York, in which scientists delivered electricity through sensors on the skulls of chronic migraine patients. They found a decrease in the intensity and pain of their headache attacks. The researchers were unable to completely explain how or why at that point in time.
Alexandre DaSilva, assistant professor of biologic and materials sciences at the U-M School of Dentistry and director of the school's Headache & Orofacial Pain Effort Lab, says the new study helps to explain what happens in the brain that decreases pain during the brief sessions of electricity.
DaSilva and colleagues administered an intravenous radiotracer that reached important brain areas in a patient with trigeminal neuropathic pain (TNP). TNP is a type of chronic, severe facial pain. The team applied electrodes to electrically stimulate the skull right above the motor cortex of the patient for 20 minutes during a positron emission tomography (PET) scan. This type of stimulation is called transcranial direct current stimulation (tDCS).
The radiotracer was designed to indirectly measure the release of mu-opioid in the brain. Mu-opioid is a natural substance that alters pain perception, and in order for opiate to function, it needs to bind to the mu-opioid receptor. The team assessed levels of this receptor during the study.
"This is arguably the main resource in the brain to reduce pain," DaSilva said. "We're stimulating the release of our (body's) own resources to provide analgesia. Instead of giving more pharmaceutical opiates, we are directly targeting and activating the same areas in the brain on which they work. (Therefore), we can increase the power of this pain-killing effect and even decrease the use of opiates in general, and consequently avoid their side effects, including addiction."
DaSilva says that most pharmaceutical opiates, especially morphine, target the brain's mu-opioid receptors.
The dose of electricity is very small, especially in comparison to other electric brain treatments. For example, electroconvulsive therapy (ECT) used to treat depression and other psychiatric conditions uses amperage ranging from 200 to 1600 milliamperes (mA). tDCS protocol, on the other hand, delivers only 2mA to the brain.
The patient's threshold for cold pain was improved by 36 percent from just one session, but not the patient's clinical, TNP/facial pain, suggesting that repetitive electrical stimulation over several sessions are required to have a lasting effect on clinical pain as shown in the team's earlier migraine study.
The research team has completed further study with more test subjects. The initial results seem to confirm the findings of this current study, but they say further analysis is necessary.
The team plans to investigate long-term effects of electrical stimulation on the brain and find specific targets in the brain that may be more effective depending on pain condition and patient status. The frontal regions, for example, may be more efficacious for chronic pain patients with symptoms of depression.