Glycine and GABA: Glycine is one of the 20 amino acids. Some neurons absorb this and it slows down electrical activity in the nervous system. Another one is gamma-aminobutyric acid (GABA). But the two we really want to focus on are serotonin and endorphins.
Serotonin is actually made from the amino acid tryptophan. While most amino acids have the ending of -ine, tryptophan doesn’t. It’s converted by some of our neurons to become 5-hydroxy tryptamine (serotonin). So serotonin is chemically known as 5-OH Tryptamine made from the amino acid tryptophan. Serotonin is very important for putting someone to sleep. It is important in natural/sleep wake patterns. This raises a whole new issue, since we know amino acids are acting like neurotransmitters. If we eat food that contains amino acids, does that affect human behavior? The effects are subtle. The effects are not as strong like it is with drugs. There’s a lot of tryptophan in turkey which is converted by the neurons into serotonin. But is that why they get sleepy after thanksgiving?
First off, people eat 3-4 times the normal volume of food during Thanksgiving. Secondly, they’re eating foods very high in carbs (yams, stuffing, bread). All these things make us very sleepy. Milk is also high in tryptophan (proverbial warm cup of milk). There are also cheeses high in the amino acid tyrosine that convert into the catecholamine’s. So it’s probably not the tryptophan in turkey, but the whole combination.
Endorphins is a contraction of the word endogenous morphine meaning we have a neurotransmitter that comes from us that works like morphine. The next time you take heroin, it mimics the action of the endorphin neurotransmitter. So when do endorphins get released? Orgasms. Orgasms are the next best thing to taking heroin. But that lasts only for some minutes or an hour. If you want to feel relaxed and sleepy for hours, then take heroin. There’s also something called a runners high that’s associated with an extended exercise session and the postulation is that is from the endorphin release. Narcotics stimulate those endorphin receptor sites for hours instead of minutes.
Why do we need these inhibitory neurotransmitters?
By having both inhibitory and excitatory, we could weigh different factors and make decisions. So it helps with decision making. When you go to sleep do your ears stop working? No. If it stopped working, your alarm wouldn’t work. Your ears are working 24/7, so how come you’re not hearing anything when you’re asleep? Because your brain is ignoring everything and that’s due to these inhibitory neurotransmitters which allow us to ignore stimuli or input signals. We will eventually talk about the role of neurotransmitters in terms of ADD, because that’s when somebody doesn’t have enough of the inhibitory neurotransmitters.