Nudging the Brain Toward Addiction
Lab Tests Show a Single Dose of Morphine May Affect the Brain
April 25, 2007 -- A single dose of morphine may affect a brain region
involved in addiction, making addiction more likely, scientists report in
They studied rats, not people, to see how one dose of morphine affects the
brain's ventral tegmental area (VTA).
The VTA is a brain region involved in the development of drug addiction,
write the researchers, who included Julie Kauer, PhD, a professor of medical
science at Brown University.
Kauer and colleagues focused on certain nerve cell connections in the VTA
that usually limit levels of a brain chemical called dopamine.
One dose of morphine blocked those nerve cell connections in the rats'
brains. That created a surge in dopamine levels, throwing off the brain's
"It's as if a brake were removed," Kauer says in a Brown University
The activity in the rats' brains after one shot of morphine "could
increase vulnerability to addiction," Kauer says. "The brain may, in
fact, be learning to crave drugs."
The dopamine-inhibiting nerve cell connections in the VTA may be good
targets for new drugs to treat addiction, note Kauer and colleagues.
Their study appears in Nature.