Just one dose of morphine can permanently change the brain

Depressing, isn't it? Especially since heroin turns into morphine once it enters the body.

"A single dose of morphine may affect a brain region involved in addiction, making addiction more likely, scientists report in Nature. 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 chemical balance.
"It's as if a brake were removed," Kauer says in a Brown University news release.
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."

Definitely makes chemical dependency tough to treat, since people are causing irreversible neurochemical brain changes. Hopefully they'll eventually make better drugs to fix this someday.

http://www.webmd.com/mental-health/news/20070425/nudging-the-brain-toward-addiction?src=RSS_PUBLIC