Dueling with Depression: Of Mice and Exercise

Turns out mice can get depressed. Like, really depressed.

So much so that in 2014, scientists at the Stockholm Karolinska Institutet observed mice that were so despondent, they didn’t even bother trying to navigate a maze filled with cold water. The mice just remained motionless and froze.

What’s the point? Those scientists are just going to throw me back into the maze when I finish. Same routine, day after day after day. Why bother?

Certainty sounds familiar. There are weeks when life feels like a continual maze of responsibilities and obligations and dead ends. Sisyphus pushing that damn boulder up that damn mountain. And what does it all amount to in the grand scheme of the universe? Is anyone going to be reading articles by Mike Yost 100 years from now?

Nope.

But I do find it a little comforting that falling head-first into an outright existential crisis, splintering the will to exist, isn’t limited to human beings. And how did these mice get depressed? Lack of serotonin in the brain? Loneliness? The realization of their own finitude?

Nope.

It was scientists restraining them or lightly shocking them into hopelessness. Yeah. Depressing, isn’t it?

So why the hell are Swedish scientists shocking mice into depression? It was to discover why exercise helps fight against depression (obviously).

I’ve heard it thousands of times. I’m sure you’ve heard it, too. Hell, I’ve written about it. Regular exercise has been shown in numerous case studies to combat depression and anxiety. I can tell you from personal experience that exercise helps (though it doesn’t cure).

But how? What specifically is happening in the body and/or brain when you exercise that shoots depression in the knees? Is it that deluge of endorphins known as “runner’s high”? Is it just crawling out of that troll cave that is your bedroom?

Well, no one really knows for sure, but those Swedish scientists had a hunch.

Science Dump: When you exercise, your body generates an enzyme called PCG-1alpha1, and this enzyme affects another chemical in the body called kynurenine, generated when you’re stressed (like being shocked or thinking about the meaningless of existence). Kynurenine passes through the blood-brain barrier and inflames the brain, which can lead to harmful changes in mood. (An inflamed brain is a depressed brain.) The PCG enzyme breaks down kynurenine so that it can’t pass into the brain, stopping the inflammation. (An uninflamed brain is a content brain.)

So, the Stockholm scientists bred mice already flooded with high levels of PCG-1alpha1, essentially creating exercised mice — without the exercise. The pre-exercised mice were more resilient when shocked, finding their way out of the cold-water maze instead of becoming depressed and freezing.

The peer-reviewed study, published in Cell, concluded that reducing “kynurenine protects the brain from stress-induced changes associated with depression.”

Now, if only those Swedish scientists could find a way to bottle PCG-1alpha1, you could shoot up your daily exercise routine before digging into a pan of pot brownies and watching an entire season of Star Trek: The Next Generation. (Make it so!)

I feel my depression lifting already.