Oxytocin boosts confidence and lengthens telomeres
Ironically, as the Internet shrinks the globe and the world becomes increasingly better connected, record numbers of people are admitting to being lonely. And, as she explains to Chris Smith, Gerlinde Metz has been discovering that this could have significant impacts on the way our brains work, how healthy we are and even how well we age; the hormone oxytocin is a key player...
Gerlinde - We're very interested in novelty seeking and we were actually using a rat model - rats - that were housed either in a social condition housing with 10 or 11 individuals per cage, or a two or three individuals per cage as a more smaller group setting; and then we testing their behaviour in terms of a field, which has like a corridor on the outside and an open space on the inside; and usually rats try to be on the safe side when they explore a novel environment, so they try to hide in the corners or close to the walls, and what we were interested in was how much time do those rats that had social experiences - over the control conditions of only two or three animals per cage - how much time would they spend in the centre of the field, which is the more open space and potentially a more dangerous space in nature...
Chris - And what makes you think that oxytocin has a role to play in that, and how did you measure that?
Gerlinde - So oxytocin is a hormone which is classically linked to the birth process, and also pair bonding, helping each other, sharing and generosity actions. And we wanted to see if oxytocin is also linked to behavioral changes and this is what we've actually observed: that the female rats especially responded very well to the social housing conditions - so they were actually more brave in exploring - and they were also investigating novel objects that we gave them. We also saw this effect in the male animals, but it was a little bit weaker than in the females overall.
Chris - So you can show that when you put these animals into this socialised environment they respond with an elevation in the baseline of oxytocin in their brains. So you can say that effect is happening and you can see behaviorally they spend more time being adventurous, and you're saying that one is is linked to the other?
Gerlinde - That's right. We've wanted to do a causal study here so we gave these animals an antagonist that is a chemical that blocked the effect of oxytocin. So these animals acted as if they had no oxytocin in their system. So if oxytocin was involved in the behavioral phenomenon that we were seeing, this should have blocked this effect in novelty seeking and adventurous behaviour. And that's exactly what we saw, so these animals that before were investigating more dangerous spaces more often now were hiding away closer to the wall spaces and in the corners when they had this antagonist chemical.
Chris - Why do you think oxytocin does this, and why do you think it does it more to the females than the males?
Gerlinde - So this is a really interesting question. The females showed a really astounding significant difference here, which, I think, might have an evolutionary background. First of all there's a biological phenomenon in that the females are more sensitive to oxytocin. They have more receptors for that in their brains, so certain brain areas are more receptive to the effects of this, but also evolutionarily there might be a benefit for actually the males not paying so much attention to the oxytocin in a biological way, because when they go out hunting or they're attacking invaders they have to fight them. They have to be a bit more aggressive and this would be very difficult if they were acting under high oxytocin levels all the time because this helps social bonding and being generous and sharing resources.
Chris - If one thinks about a woman who's recently given birth though we know that the birth process produces a very big surge in oxytocin, both during the birth and the suckling reflex that happens. Would not the safest thing for that person to do to be to retreat and and stay away from danger with the newborn so that there was less risk of predation? So isn't that sort of slightly counter intuitive? Because the oxytocin you're saying should make her much more daring.
Gerlinde - Well that is definitely a really good question you're bringing up. So as you point out, which is correct, the social bonding is mediated by oxytocin after the birth, also helps milk production and so on. And of course I mean the mother should rather stay safe at home. But also what we see is that with the children in tow we basically venture out a lot as mums! Being a mum myself I took my my daughter out on walks a lot and showed her the world. So maybe there could be a benefit to that: we seek social support. We attend child care groups. We meet with other mothers; we meet with family members. So I think that's a great benefit of having this oxytocin linkage in bringing us out and about and sharing our experiences, which also would reduce stress because oxytocin is kind of the candlelight dinner hormone: it down-regulates the stress response and I think it might make a mum a bit more relaxed!
Chris - It's nice sort of confirmation and corroboration of what we thought was going on, so it's nice that you've come at this from a novel angle and been able to provide additional weight. But why does this actually matter this research?
Gerlinde - So we also had another measurement in our study, which is measuring telomere length. Telomere length is a biological marker of age. Biological age as a really interesting measurement because it can actually predict longevity and successful ageing; and what we did here, we measured telomere length, which is like the plastic tip on a shoelace: it protects the end of a chromosome, and with each cell division the telomere length will shrink. So a shorter telomere length would be indicative of a more advanced biological age. And so we looked at telomere length and we found telomere length was larger in animals that were exposed to the social housing condition. So here we have a really nice correlation between successful ageing and social experiences throughout a lifetime. And I think this has a lot of implications also in understanding what can do about having healthy life trajectories, helping our ageing population to do successfully and protect brain health as well!