New Studies Show that Alcohol Makes You Stupid and that Stress Makes Mice Want to do Coke
|Stressed-out mice find that nothing is as good as Coke, er, coke.|
Anyhoo, it turns out that when mice get stressed, their brains release hormones that tell the kappa-optoid receptors on their neurons to release a protein (called p38α mitogen-activated protein kinase, or p38α MAKP) that tells the cells to produce less serotonin, the neurotransmitter that helps keep them happy. When the mouse-brains have less serotonin, the mice start acting like depressed coke addicts.
"We call these responses 'depression-like' and 'addiction-like' behaviors because we can't ask mice if they're addicted or sad," said Wash. U. researcher Michael R. Bruchas in a press release. "But just as depressed people often withdraw from social interactions, stressed mice do the same thing. We also observed that stressed mice return more often to the place where they received cocaine."
However, when the scientists used new genetic technology to disable the p38α MAKP protein, the mice stopped acting withdrawn and looking for their next fix, even when they were in a stressful situation -- in this case, stuck in a cage with a particularly obnoxious "aggressor mouse." (Bruchas compared the aggressor mouse to a mean boss or a bully.)
These studies, naturally, have implications for humans.
"When people take antidepressant drugs called selective serotonin reuptake inhibitors, or SSRIs, to relieve depression, the drugs act on a cellular pump called the serotonin transporter, and this results in more serotonin in the brain," Bruchas explained. "We think that the involvement of the p38α protein and kappa-opioid receptors represents an important finding in figuring out how it is that cells regulate depressive and addictive behaviors."
Next up: Running experiments to see if disabling p38α MAKP affects serotonin levels in amphetamine- and nicotine-addicted mice.
The study was written up in the journal Neuron.