There's been plenty of research showing that when people
inhale oxytocin, they tend to have more positive social behavior: trust, generosity,
empathy and communication. But if taking one whiff of oxytocin can make you
nicer, will taking oxytocin regularly keep you nicer? If you take a bigger
dose, will it make you even nicer?
U.C. Davis researchers wanted to find out the long-term
effects of taking oxytocin, so they studied prairie voles, the monogamous
rodents that first demonstrated the positive effects of this brain chemical.
The U.C. Davis research team, led by Karen L. Bales, treated
a group of 89 male prairie voles with low, medium or high doses of inhaled
oxytocin. The medium dose was roughly equivalent to the amount given to human
subjects in lab studies.
They began giving the prairie voles one daily dose of oxytocin
when they were weaned at 21 days old, and continued to give it to them through
day 42, the time they reach sexual maturity.
"We were trying
to approximate ages 12 to 17 in humans," Bales told me in an email. Because
so many parents of children with autism spectrum disorder are turning to
oxytocin products they've bought over the internet in hopes of increasing their
kids' sociability, the short-lived voles offer a way to model the possible
effects of long-term dosing of an adolescent.
The study also wanted to look at possible dose-dependent
differences: If one dose creates an effect, it doesn't necessarily follow that
a different dose will create the same effect. In fact, she cites research
showing that in schizophrenic patients, 20 IU of oxytocin increased emotion
recognition, while a dose of 10 IU actually decreased it.
There was one troubling result: The male voles treated with low
or medium doses of oxytocin were actually less likely to bond with a female --
and this effect lasted two weeks after treatment stopped. That could be
equivalent to years in a human life.
The female voles in the study also seemed to be less
interested in mothering.
Bales thinks that this effect could be attributable to
down-regulation of the oxytocin receptors or oxytocin-producing neurons; that
is, with external oxytocin flooding the receptors, they might become
desensitized, while the oxytocin-producing brain cells might lower their
production because it's not needed. It also could be attributable to changes in
the vasopressin system, she suggests. Vasopressin is another brain chemical very
similar to oxytocin that seems to be more important in male bonding.
She says, "I originally thought that we would see the
most changes with the highest dose of oxytocin, and that would be because of
flooding oxytocin receptors and binding to vasopressin receptors. But
since we had the most changes at the lowest dose, that seems less likely.
Males do seem to be especially sensitive to developmental exposure to
oxytocin...perhaps because they rely less on it normally?"
Bales' work is with prairie voles, not people. But so far,
what vole research taught us about oxytocin is quite applicable to humans. We
think we're so different from this tiny, humble creature. But in fact, the
genetic difference between Homo sapiens and other mammals is very small.
It's not clear how applicable the results of this study
might be to older humans, but certainly the body's receptors are constantly in
a state of flux, responding to external changes. And it's well known that
treatment with a hormone can cause the body to produce less of it.
Bales plans to do
more studies using voles of different ages, and also to look at different
lengths of treatment.
Meanwhile, if you
are self-experimenting with oxytocin, it's a good idea to keep your dosing acute:
once in a while with plenty of time for your body to go back to its natural
Here's the ref: Bales, K.L. et al. Chronic
Intranasal Oxytocin Causes Long-Term Impairments in Partner Preference
Formation in Male Prairie Voles. Biological Psychiatry 2012.