Morphine and cocaine both do a very good job of hitting the reward centers of your brain — but new research has shown that they do so in opposite ways.

Up until now, most experts believed that opiates and stimulants used the same pathways to trigger the reward centers of your brain, making using the drugs rather pleasurable — but turns out they're very different. In this week's issue of Science, researchers have discovered a mechanism that alters them oppositely.

The scientists were working with mice to surpress the protein brain-derived neurotrophic factor (BDNF), which would would dampen the effects of stimulants like cocaine. What they found, surprisingly, was that knocking down the BDNF in part of the brain had the opposite effect on morphine, causing it to increase dopamine excitability and reward you more. The opposite held true, too — boost BDNF, and morphine becomes less potent.


They were also able to identify the genes that regulate BDNF when associated with morphine addiction.This also seems to suggest that heavy morphine users might have a much greater reaction to cocaine.

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