Neurotransmitter Diminishes Morphine's Potency in the Brain
While a neurotransmitter is enhancing morphine’s effects in the spine, it also is diminishing the drug’s addictive characteristics in the brain, a Yale study shows.
“In the spinal cord, the neuropeptide galanin makes morphine a better pain drug. It actually can increase its potency up to 10 times,” said Marina Picciotto, assistant professor of psychiatry and pharmacology at Yale School of Medicine . “What this study says is that at the same time as galanin increases morphine’s potency as a pain drug, it is decreasing its ability to be addictive.”
The study published in a recent issue of the journal Neuropsychopharmacology also could have implications for efforts to develop galanin mimics as an appetite suppressant. Galanin is a neuropeptide that stimulates feeding, but it also neutralizes the reward and withdrawal effects of morphine in the brain, she said.
Neuropeptides are a chain of amino acids that are used in the brain to communicate with other nerve cells.
“There are many drug companies making small molecule drugs to block galanin to use as an appetite suppressant. But our data shows that galanin can counteract the reward and withdrawal mechanisms of morphine in the brain,” Picciotto said. “What this means is that galanin blockers might decrease appetite, but they might also have the effect of stimulating the reward and withdrawal affects of opiates in the brain.”
She said galanin also would be effective in increasing the efficacy of opiates as pain medication.
Picciotto said she and her colleagues became interested in galanin because of the way it interacts with morphine in the spinal cord. Since galanin increases morphine’s effects in the spinal cord, the investigators theorized it also would intensify morphine’s addictive characteristics in the brain, which turned out not to be the case.