Kisspeptin: the serendipitously named reproduction hormone
I spoke with Matt Wall about a recent study he co-authored investigating the role of kisspeptin on emotional brain processing for my Physiology and Behavior show. Here’s the transcript of the episode.
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Dan: A paper recently came out on how the hormone kisspeptin modulates sexual and emotional brain processing. I asked Matt Wall, one of the study co-authors, about the origins of kisspeptin and it’s unusual name.
Matt: Kisspeptin is a peptide hormone, it was discovered in the late 90s, and it was first thought to play a role in cancer. It was discovered in a town called Hershey, Pennsylvania, where there’s also a massive factory where they make Hershey’s chocolates, in particular the little chocolates they call Hershey’s kisses, hence the name, kisspeptin.
Matt (continued):It was only later it was found that it had a big role to play as a sex hormone, particularly in puberty, so it’s the hormone that starts off the whole cascade of other hormones that you get that kick off puberty. Rats that don’t have the kisspeptin gene don’t go through puberty and they stay sexually immature.
So the people that named it originally, even though they didn’t know it at the time, they gave it an incredibly appropriate name.
Dan: In this fMRI study 29 healthy heterosexual men were administered either kisspeptin or placebo intravenously in separate visits to better understand kisspeptin’s effects on neural activity.
“So what we think is that that kisspeptin serves as a link between the brain systems that are processing emotional, sexual, and love-related information and the rest of the bodily reproductive system.” — Matt Wall
Matt: What we did was we showed people a lot of different emotional pictures, some were sexual, romantic, positive or negative, different facial expressions, and we found that kisspeptin enhanced activity in certain regions of the brain that are known to be related to emotional processing, like the amygdala, other bits of the limbic system, the anterior cingulate, but specifically in relation to the sexual and romantic images — nothing else.
So what we think is that kisspeptin serves as a link between the brain systems that are processing emotional, sexual, and love-related information and the rest of the bodily reproductive system.
Dan: An important question with peripherally administered peptides is whether they actually reach the brain, as the blood brain barrier often prevents molecules from entering the brain compartment.
It’s possible to administer a medication and see changes in brain activity, but this doesn’t necessarily mean that it’s directly acting in the brain. Perhaps the peptide has an indirect effect on the brain via the activation of peripheral receptors.
To test this, the study authors administered radiolabelled kisspeptin peripherally to male mice. They found increased levels of radioactivity, in various areas areas of the brain, suggesting that these brain imaging effects were probably due to direct action in the brain, which is known to contain kisspeptin receptors. Of course, these results to be replicated in humans, but observing this in mice is a great start.
This study helps open the door for kisspeptin’s development as a treatment for reproductive dysfunction. Although researchers have already demonstrated its role in non-human mammalian reproduction, this is the first study to demonstrate that kisspeptin can influence the neural processing of reproduction related images in humans.
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