As you may have noticed, I have an ever-growing hunger for words. Actually, I hunger for knowledge of all sorts of types. Come to think of it, I hunger for food too… fortunately, I exercise, and have gotten better at eating less. Otherwise not just my knowledge but my weight and waistline would be growing.

Interestingly, there is something of a biochemical connection between, on the one hand, physical hunger and growth and, on the other hand, learning and memory. The link is something that demonstrates yet again that – as you may have observed in my note on Suzanniwana – scientists also often have a deep-rooted love for language. The link, you see, has a name that is radically original: ghrelin.

What is ghrelin? It’s a peptide that serves a few functions in the body. It is associated with hunger – it increases before eating and decreases after – and it also appears (based on animal studies) to stimulate learning and memory via the hippocampus, which suggests that you may learn better on an empty stomach. In fetuses, it seems to promote growth. Higher levels of it are also associated with short sleep duration and obesity – if you don’t get enough sleep, you are hungrier and get fatter. (Which means my frequent late nights writing word tasting notes aren’t helping my weight.) I don’t know how one resolves the apparent conflicting issue that short sleep is not generally associated with learning and memory.

And where does ghrelin get its name? Perhaps from those gremlins that chase around in your stomach – or in your head? Or the sound of your stomach growling? Maybe from the fact that if you turn LI into U, GHRELIN is an anagram of HUNGER? No, it comes from an original root – I already told you it was radically original. The hormone is associated with growth; it is a growth-hormone-releasing peptide. As it happens, the Proto-Indo-European (PIE) root related to “growth” is ghre. (What is Proto-Indo-European? It’s the reconstructed ancestor of the Indo-European languages, spoken roughly 6000 years ago. The language family has grown considerably since then, and our knowledge of it is still growing.) It’s a nice coincidence that ghre also looks like an acronym for growth-hormone-releasing. And the lin? A common suffix for hormones.

How do you pronounce it? Don’t bother trying to make a voiced aspirated velar stop at the beginning, and don’t linger on h – just treat the h as silent for the purposes of Modern English. And as you roll the idea of this hormone around in your mind, and as the hunger created by your brain use starts your stomach up, roll this word around in your mouth – a nice piece of PIE.

6 responses to “ghrelin

  1. Aha – I just saw this word yesterday, or maybe it was this morning, or perhaps when reading yesterday’s paper this morning, in a brief newspaper column about gaining weight. Coincidence? Or synchronicity? (Or did you simply read the same article?)

  2. I wonder if ‘Ghrit’ or ‘Ghritam’ ; medicated ‘Ghee’; used as medicine for growth; which contains fat; comes from the same source. Many Indian households use Ghee, instead of butter for day to day cooking and eating.

  3. “I don’t know how one resolves the apparent conflicting issue that short sleep is not generally associated with learning and memory.”

    I don’t get you here. Are you saying that amount of sleep taken is not associated with learning and memory? In my opinion it is highly correlated with learning and memory.


    Being hungry, on the other hand reinforces more learning and intelligence, according to some specialists because it resembles our ancestors who were forced to invent new ways to prey in order to get their food.

    • The point is that high levels of ghrelin are positively correlated with, on the one hand, learning, and on the other hand, lack of sleep, whereas as far as I know lack of sleep is negatively correlated with learning and memory. More learning = more ghrelin, more ghrelin = less sleep, but less sleep = less learning. I suspect that the correlations are weak enough not to conflict with the countervailing effects.

  4. ” I suspect that the correlations are weak enough not to conflict with the countervailing effects.”

    To a T. 🙂

  5. Another synchronicity. Have recently read several articles on this hormone and how it relates to a person feeling satisfied, satiated, and content at the end of a meal. Dollar signs are teeming in front of pharmaceutical eyes, the next big diet pill, miracle wonder. Except, as you say, ghrelin is not straight forward in its actions and just giving a person more ghrelin or suppressing its occurrence doesn’t linearly correlate. And, as with the sleep cycle, ghrelin interacts with many other body systems. No magic bullet yet, but I bet pharma giants are putting in major overtime hours on this little hormone.

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