The Splort Hormone

At the end of my last post, I promised I’d explain more about inner dialogue, and get into some practical tips on self-programming. A draft of that write-up is almost finished [SCIENCE UPDATE! It’s here.] but I came across an article today that brought up some intriguing points – and some common misconceptions – about neurochemistry. I couldn’t resist such a perfect opportunity to explain some concepts more clearly.

Eye (and nose) contact.

The article is mainly about the chemistry of eye contact, and…well, I’d better let the author speak for herself.

A loved one’s lingering look can trigger a rush of happiness, but too much eye contact with an acquaintance or a stranger can bring on sudden discomfort. How, exactly, does eye contact affect us, anyway?

Sounds pretty frickin’ fascinating so far, right? So let’s dive in. After a few introductory paragraphs, the author gets to the good part – the neuroscience. She explains that authentic expressions affect other individuals’ emotional responses differently than faked ones do – which is accurate, and backed up by some intriguing scientific research.

But the next bit was what made my Science Radar bleep a warning:

Oxytocin, also known as the “love” or “cuddle” hormone, plays a big part in [making our hearts flutter]. It’s a feel-good chemical that’s released when we feel bonded with someone, either emotionally or physically. The release is prompted by a warm hug, holding hands, falling in love, and so forth.

Well… that’s only sort of true. And sort-of-true statements often lead to confusion, which is why I want to explain the oxytocin situation as clearly as I know how.

Oxytocin is often called the “love hormone” or the “cuddle hormone.” That’s probably because it can be detected at raised levels in human blood plasma around the time of orgasm. If you Google oxytocin, most of the results will contain words like “love” or “cuddle.” You’ll also see a lot of articles asking, “Can oxytocin do [X]?” and “Does it do [Y]?” There’s plenty of speculation floating around – but the fact is, scientists are still unraveling the complex relationship between oxytocin and human emotions.

For example, oxytocin levels seem to rise during physical sexual arousal in women, and “spike” around the time of orgasm. But women’s bodies also release high levels of oxytocin during cervical dilation (i.e., expansion of the vaginal canal) during second- and third-stage labor, as well as when their nipples are physically stimulated for breastfeeding by an infant.

Meanwhile, in men’s bodies, oxytocin levels seem to just rise and then level off during sexual arousal. Some studies have found a mild spike around the time of orgasm, while others haven’t. Oddly enough, at least one study has found that oxytocin levels rise highest in men who stimulate themselves to orgasm. So we might just call oxtyocin the “splort hormone” and be done with it – but (as usually happens with science) there’s a lot more to it than that.

A sexy, naked oxytocin molecule.

First of all, who wants to know what oxytocin is? It’s a polypeptide hormone (i.e., a hormone created when a string of amino acids join together in a specific way). It’s produced in the pituitary gland of mammals. In very general terms, oxytocin is related to changes in the contractile properties of reproductive tissue. Some studies seem to show that oxytocin induces or promotes those changes; other scientists think its presence is just a reflection that they’re happening.

But even that’s just the tip of the oxytocin iceberg. Over the past few years, scientists have learned a lot about this hormone by studying some of the effects it can produce.

In mice, oxytocin in taste buds has been shown to inhibit the desire to keep eating. In the hypothalamus, it helps rodents time their birth cycles. In rats, a raised oxytocin level in the hippocampus decreases responsiveness to stress, and allows wounds to heal more quickly. In humans, it’s been shown to increase generosity toward strangers. Then again, it also makes people racist:

The love and trust oxytocin promotes are not toward the world in general, just toward a person’s in-group. It turns out to be the hormone of the clan, not of universal brotherhood.

Here’s where we finally come around to those ideas about oxytocin being a “cuddle hormone.” Oxytocin in blood plasma has been shown to spike when a person receives a friendly hug, or even an extended gaze. But whether the hormone is rising because we’re feeling loved – or if it’s just because we’re responding emotionally to the behaviors of other individuals in our species – is a question that’s still open.

So, like I said: sort of true.

To be honest, I’m glad I found that article, and I hope others do too – anything that helps get people excited about neurophysiology is awesome as far as I’m concerned. But I like to present things clearly, with plenty of specifics. I think that, as a journalist, if I can’t sit down and describe any given detail of my subject clearly and succinctly, I haven’t done enough research, and it’s time to hit the books again.

That’s just one guy’s opinion, obviously. But it’s the way my connectome is wired.

6 thoughts on “The Splort Hormone

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