Cocoa Madness: aberrant chocolate-seeking mice run rampant!

Well, not quite. I got an intriguing abstract in my inbox earlier today, to this new paper from BMC Neuroscience:

Here using a new conditioned suppression paradigm, we investigated whether the ability of a foot-shockpaired conditioned stimulus to suppress chocolate-seeking behavior was antagonized by previous exposure to a chronic stressful experience, thus modeling aberrant chocolate seeking in sated mice. Our findings demonstrate that while Control (non-food deprived) animals showed a profound conditioned suppression of chocolate seeking during presentation of conditioned stimulus, previously food deprived (FD) animals revealed a clear-cut preference for the chamber containing chocolate, thus indicating that previous exposure to a food restriction experience induces food seeking/intake despite its possible harmful consequences, which is an index of compulsive behavior.

Aberrant chocolate seeking? I plead guilty! Wait, this isn't about me. Actually, all the article shows is that when presented with a chamber containing chocolate, mice were dissuaded from entering by an electric shock - unless they had previously been starved. The mice weren't starving at the time of the experiment, mind you; they'd recovered and gained back the weight they'd lost. But the previous experience of starvation overcame their aversion to the shock, and they continued entering the chocolate chamber despite it. ("entering the chocolate chamber" would be a good band name.)

Of course my cynicism reared its ugly head immediately and said "they totally used chocolate just to get A) internet buzz, B) completely misleading mainstream media coverage, and C) invited to be on Oprah." (Consider this post my contribution to A). But the authors plead innocent, saying "milk chocolate was chosen based on previous studies showing its rewarding properties in animals. In addition, chocolate is the most commonly craved food and chocolate craving and addiction have been proposed in humans."

Uh-huh. Whatever you say, dudes. Mmmmm, chocolate mice.

LA Burdick's Chocolate Mice.

Read the whole article here or a press release here, or just wait until tomorrow for the mainstream media to beat the heck out of this one.

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Is chocolate the most commonly craved food? I get cravings for various other sweet, salty, and/or fatty foods in addition to chocolate.

It's not all that surprising to me that a history of food deprivation would lead mice to ignore electric shocks.

Good question. I didn't look up the article they cited to support that statement, but I suppose it's plausible that someone did a study once and found self-reported chocolate craving was higher than anything else. I can't think of anything obvious that would be more commonly craved - in part because many things would satisfy your salt craving - pretzels, peanuts, potato chips - thus diluting self-reported craving for any one item. Chocolate on the other hand is pretty much the only food of its genre. But this is all just speculation, I didn't look up the reference.

Not sure this study has proved anything except that when mice get hungry they'll put up with all kinds of suffering to get food.

Nothing wrong with chocolate-seeking behaviour anyway!

I will admit to the occasional craving for chocolate (almost always dark chocolate), but much more frequently I really crave bacon.

Generally, in reward related studies, chocolate is used. Basically, when you're working with rodents and food reward, use either sweet or fat, or preferably both. Chocolate fulfills both those criteria and is thus really happy. Also, MANY of the scientists I know personally will use chocolate or some other highly palatable food as an excuse to keep it in the lab ("dang, we're out of Oreos AGAIN! Those mice, they just love the Oreos..."), so keep the whole "keeping chocolate in the lab" bit in mind, which i imagine was a LOT more salient to the scientists than the possibility of media attention. :)

Sure chocolate is used in reward studies - BUT given that BMC Neuroscience is emailing me press releases with "chocoholic" in the title the week before Valentine's Day, methinks there is far more than an optimal self-administration curve at stake here. I'm just sayin', I didn't get an email about crackhead mice.

So do tweeker mice start taking their cages apart in the middle of the night, have greasy tangled fur, and lose all their teeth? (Sorry. Been reading too much local news lately.)

I agree with your assessment about chocoholic papers, though.

Chocolate mice? I could get by with them - at a squeak, but wouldn't they melt after a while due to the heat from your hand as you click around your computer screen?