This edition of Science Sunday was inspired by a somewhat-old post at Liberal Debutante, which begins as follows:

Apparently a new drug to battle obesity would have effects on children’s brains…

Other researchers have found that cannabinoid receptor blockers interfere with neural connectivity in rat brains — a phenomenon that in humans is associated with depression.

My response? DUH. There are other silly things in the post (in spite of whatever sympathy Katie’s views on body image deserve): yes, it is that hard not to eat fast food, since we evolved to value every drop of fat we could get, and the research is interesting, not ridiculous. But I want to focus on these first two sentences.

In my Botox post, I explained that poisons work not based on any inherent poisonousness, but by the way they interact with the complicated mechanisms that make our bodies work. Thus with drugs that are supposed to be beneficial. If you want a drug to make people less massive, for example, you must do one of two things: make less mass go in the top end, or make more mass go out the bottom end. The second option generally involves altering the digestive system so that less food is absorbed. Ads will use the pleasant-sounding phrase “pass through your body,” but basically we’re talking weight-loss through induced diarrhea, not pretty.

The first option means altering behavior. Altering behavior means altering the brain–we need to get over the surprise at the idea that when people do things, and have things done to them, SOMETHING HAPPENS IN THE BRAIN!!!!!!!!11. No one should ever have to say that, and that alone, outside introductory psychology class. What we’re working on now is what, specifically happens in the brain when people do specific things and have specific things happen to them.

Now let’s talk about cannabinoid receptor blockers. Those, you will be interested to know, are things that block cannabinoid receptors. Well, what are cannibinoid receptors? Receptors in general are proteins that detect chemical signals. Many of these receptors were first identified based on the drugs that affect them: nicotinic receptors are affected by cancer sticks, opioid receptors are affected by smack, cannabinoid receptors are affected by reefer. But they don’t exist so that you can enjoy the effects of these drugs, they exist so that the body can communicate with itself. These drugs are tapping in to pre-existing happy-systems rather than being distilled essence of happy, just as poisons are screwing up subtle mechanisms you need to live, rather than being distilled essence of death. It helps to have different systems controlled by different things, so different signal-chemicals have different signature effects, but that’s a function of how the body’s set up, not anything inherent to the chemicals.

So it seems like cannabinoid receptors are involved in the apatite, so cannabinoid receptor blockers act as “munchies blockers,” in the phrase coined by the linked article. But yeah: you’re interfering with connections in the brain. There’s no other way to do it. And since the cannabinoid system is involved with more than one thing, including feeling good, blocking it has multiple effects, including feeling bad. Your body’s self-produced opioids and cannibinoids are very important for your normal, every-day functioning. Don’t go blocking them willy-nilly.

A corollary to all this is that drugs don’t contain a mix distilled essence of main effect and a distilled essence of side-effectiveness, so that the side-effects would go away if only we could separate the two components out. At the level of chemistry there may be only one thing going on, and if there’s multiple things, it may in fact be that what we call “side effects” are lessened because a secondary, chemical-level effect cancels out unwanted consequences of the main chemical-level effect.

After writing this post being somewhat flippant about illegal drugs, I should include a customary anti-drug message. Your nervous system is very complicated and un-idiot-proof. This means that if you are an idiot, you should stay 500 ft. away from your nervous system at all times. Er, I mean, it means you should be reluctant to screw with it. This means both blocking it, and artificially stimulating it.