Flipping The Brain's Addiction Switch Without Drugs

ScienceDaily (May 29, 2009)

When someone becomes dependent on drugs or alcohol, the brain's pleasure center gets hijacked, disrupting the normal functioning of its reward circuitry.

Researchers investigating this addiction "switch" have now implicated a naturally occurring protein, a dose of which allowed them to get rats hooked with no drugs at all.

Chronic drug users, as noted by previous research, can experience an increase of a naturally-occurring protein called BDNF (brain-derived neurotrophic factor) in the brain's reward circuitry, a region scientists call the ventral tegmental area. In this study, the researchers took the drugs out of the equation and directly infused extra BDNF onto this part of the brain in rats.

The Toronto team noted that a single injection of BDNF made rats behave as though they were dependent on opiates (which they had never received). Though rats instinctively prefer certain smells, lighting and texture,