New publication – Oxytocin in Dolphins

Link to article: here

Download the paper for free until the 9th January: here

Or read the abstract on this site here

Bottlenose dolphin mother with a young calf in Scotland

I spend a lot of my time working on a hormone called oxytocin, it’s fascinating to study as it can act on many different kinds of social and parental behaviours in all kinds of animals (see this amazing reveiw for more information). However, most of the research done on the hormone so far is on laboratory animals, or captive individuals in zoos, and little is known about how the hormone functions in completely natural environments and populations. I have been trying to change this with my work on oxytocin in breeding grey seals here in Scotland, and I have also started to work on oxytocin in other wildlife species with the help of many wonderful collaborators. My new paper is all about the first of these new studies, where we detected oxytocin levels in a wild population of Bottlenose dolphins.

The aim of the study was to firstly see if it was possible to detect dolphin oxytocin, but also to see if there were any differences between age groups or different types of social groups. We worked with the Sarasota Dolphin Research Program (SDRP) in Florida, USA to collect samples from wild bottlenose dolphins over 3 years, and this enabled us to study adult males in breeding alliances, lone individuals and mothers with calves. The SDRP has studied the bottlenose dolphins living in and around Sarasota Bay since the 1970s and conducts occasional health checks on small portions of the population. This means that wild dolphins can be safely briefly captured so that measurements and samples can be collected, and any obvious injuries can be treated by vets. For example, one of the dolphins in our study had sting ray barbs in his head, which the vets were able to remove before he was released. The SDRP has enabled all kinds of research on dolphins to take place, from measuring aspects of their physiology to understanding dolphin cognitive abilities, and you can read more about the health checks and the research that comes from them on the SDRP website here.

Mother – calf pair of Bottlenose dolphins in Sarasota Bay, Florida. Photo courtesy of the Sarasota Dolphin Research Program, taken under NMFS Scientific Research Permit No. 20455

We found that we could use a test called an ‘enzyme linked immunosorbent assay’ or ELISA, to successfully detect dolphin oxytocin. By passing all the quality control checks to see if an ELISA is working properly with a new sample type, we know the values we are detecting are accurate and can be used in future studies. Most of the dolphins we studied had oxytocin levels that were comparable to other mammal species, and were relatively low. This surprisingly included the mothers that we sampled, in contrast to what we know about seal mothers who have high oxytocin levels up until they wean their pups. However, dolphin calves had much higher levels than other age classes, and these high levels were present across all ages that we studied (2-4 years old). Previous work on oxytocin in young mice, seals and humans have also showed that young infants have really high oxytocin levels compared to adults, but all these prior studies covered much shorter time frames (days or weeks). Our results suggest that the dolphin calves have elevated oxytocin levels for several years, covering the timeframe that they are still with their mothers.

This is important as oxytocin stimulates individuals to seek out and stay close to others that they share a bond with. Dolphin calves have to deal with regular separations from their mothers while they grow up, especially as mothers have to be able to shoot off in pursuit of prey while rearing calves. Previous studies indicate that dolphin calves must be able to cope with these separations or they will not survive, and that calves play an active role in reuniting with their mothers at sea. Elevated levels of oxytocin in this age class could be indicators of calves with strong bonds with their mothers and high motivation to re-unite with them when separated. In contrast, dolphin mothers may not have constantly elevated oxytocin because they must separate to successfully feed regularly. Continual hormonal stimulation for mothers to stay with a calf could therefore be completely inappropriate for this particular species. As dolphins have advanced cognitive and communication skills, oxytocin release in adults may instead be tied to specific signals from other individuals they share a bond with.

Bottlenose dolphins with a young calf in Scotland. One of the adults is likely the calf’s mother.

This study is just the first step in understanding how oxytocin works in socially complex dolphin species. It is important to understand hormone dynamics and how they impact on individual behaviour and survival as physiological mechanisms that act on these processes are often present across entire species. Oxytocin release and the behaviours this triggers to keep socially or maternally bonded individuals together can only happen if bonds can form in the first place. Bond formation relies on communication and interaction causing oxytocin release, often during critical time frames within an individual’s life. All wildlife species are facing increasing disturbance from human activities, and if individuals cannot form strong bonds or communicate to reinforce them via oxytocin release it could make life much harder for species that rely on group living like dolphins.

Many dolphin species have to live and rear their calves in areas that are increasingly disturbed by human activities, like this mother calf pair off the coast of a major tourist destination on Ibiza, Spain.

MEANWHILE: This month has been pretty hectic as I submitted my first ever fellowship application. Fingers crossed that my application will get to the interview stage, although the odds are low unfortunately with only about 1 in 10 applications being successful. In more positive news, I’ve also been working on the final version (aka the publisher proofs) of another oxytocin paper. This is a big review article that I worked on with a number of great oxytocin scientists. We met at a conference in 2018 and all work on different animal species to study various aspects of how the hormone works. We have joined forces and written a review about all the model animal species that have been used to study neuropeptide hormones. This should be out soon so watch this space!

New publication – Oxytocin is linked to increased rates of mass gain in seal pups

Newly weaned grey seal pup with a very healthy blubber layer. Pups have to go from about 15kg to over 30kg in just 18 days to stand a chance of surviving their first year of life.

Link to article: https://www.sciencedirect.com/science/article/abs/pii/S0306453019303592

Download the paper for free until the 22nd October here: https://authors.elsevier.com/a/1Zfqx15hUdMnwe

Or read the abstract on this site here

It has been a while since the last blog update on this site (for a very good reason, but more on that later), and in the time that has passed the PHATS team has been busy finalising our lab work, analysing our results and of course, writing papers. I’ll be uploading a post soon about two papers on pollutants that the PHATS team have been published since the last update (or you can read one of the papers here, the other one is still in press!). But right now, I’m going to talk about my latest paper on the hormone oxytocin and mother-infant bonding, behaviour and development.

Grey seal mother-pup pair on the Isle of May, Scotland

This paper is the last to come from my NERC funded PhD work with the Sea Mammal Research Unit, University of St Andrews. During my PhD I collected lots of different types of information on the wild grey seals breeding on the Isle of May  and North Rona, two island colonies that I would visit for months at a time to study seals. I have previously published papers showing that the more oxytocin a mother has, the closer she stays to her pup and an experiment that showed that high oxytocin definitely causes seals to seek others out and stay close to them. However, I wanted to investigate what the oxytocin levels in young pups were like when they were still with their mothers, and if there were any interesting dynamics going on, whether there were any developmental consequences for the pups.

What I found out was very exciting. It turns out that mothers with high oxytocin levels produce pups with high oxytocin levels, and I think this is due to positive feedback loops being created in both the mother and pup once they have bonded. This happens because oxytocin is often released when someone interacts with another individual they are bonded to, and the high oxytocin levels created cause the individuals to stay close together, meaning they can be exposed to even more interactions and even more oxytocin release! This has been theorised to exist in mothers and infants before, and there is evidence that it happens in socially bonded individual, even between humans and their pet dogs! However, my study provided the first evidence that these positive loops exist in completely wild animal populations living in natural environments.

Oxytocin causes mothers and pups to stay close together on a breeding colony

The next step was to see if there were links between the oxytocin levels in pups and any of their growth characteristics before they weaned from their mothers. My data showed that there was a strong relationship between oxytocin and the rate that pups gain mass. The higher the level of oxytocin, the more mass a pup gained ever day it was with its mother. While this was exciting, there might have been a straightforward reason for this, that the pups with high oxytocin are motivated to interact more with their mothers, which includes drinking milk from them. Seals have very fat rich milk, so the more a pup drinks, the more mass it will gain per day. However, I had already studied the impacts of oxytocin on the behaviour of mother-pup pairs, and found no relationship between high oxytocin and the frequency or duration of time pups spend drinking milk. Could it be true that the high oxytocin pups were somehow gaining more mass without drinking more milk? Luckily there was another way to test if this was happening, by analysing the mass change rates of the mothers.

Grey seal mothers don’t eat anything while they are on a breeding colony raising their pups. They have to build up a big fatty blubber layer throughout the year and rely on this energy store while they are on the breeding colony. The time that mother grey seals spend rearing their pups is short to help them cope with this, mothers and pups are only together for 18 days before weaning happens and the mother goes back to sea for some well-earned fish. However, this puts an incredible energetic strain on these poor seal mothers, they have to give birth, produce high fat milk and look after their pups all without eating anything. So, as seal mothers will usually loose a large amount of body mass over the 18 days they are rearing their pups, I could use the mass loss rates of the mothers in my study to see if the ones with these high oxytocin pups were losing mass at a faster rates. This would indicate they were producing more milk, or higher fat milk, for their pups to drink, causing increase mass gain in their pups. However, when I analysed the data there was no link between oxytocin levels and mass loss in the mothers. Somehow, the high oxytocin pups are able to gain more mass without any additional strain on their mothers.

Grey seal mothers are usually large and fat when they give birth (left), and newborn pups only have a thin layer of blubber under their skin. By the time pups are approaching weaning on day 18 after birth, they need to have put on a lot of weight, causing the mothers to deplete their blubber stores to generate fat rich milk for them (right).

There are a few potential explanations for the high mass gain rates I found in the high oxytocin pups. Firstly, we know that oxytocin affects behaviour and seal pups with high oxytocin are likely motivated to stay snuggled up to their mothers. This could help them save energy in two ways, firstly the pups would not be wandering around the colony, burning energy and getting into trouble with neighbouring seals. Secondly, pups that spend more time close to their mothers may be more sheltered from weather conditions, meaning they wouldn’t have to use as much energy keeping warm on the cold, wet Scottish breeding colonies. Both of these potential explanations demonstrate that, rather than putting on more mass per day, these high oxytocin pups may actually be reducing activities that divert energy away from putting on mass.

A heavy rain storm approaches the seal breeding colony on North Rona. Strong winds and wet conditions are common on Scottish seal colonies. All the white dots on the island are seal pups, resting beside their mothers.

There are also potential physiological explanations for the increased rates of mass gain in pups. A few laboratory studies have shown that oxytocin can act on development, with elevated oxytocin increasing fat tissue, impacting on muscle development and bone mass accumulation. Several studies have already proposed the physiological mechanism by which oxytocin can alter mass changes regardless of the food an individual is eating. It is possible then, that the high levels of oxytocin in the pups is altering their physical development and giving the pups a good start in life by helping them put on weight as fast as possible.

Any factor that helps seal pups put on weight is really important. The likelihood a seal pup will survive its first harsh year at sea, learning to survive in the wild, is directly tied to how fat it managed to get while still with its mother. But a seal mother cannot just pour all their resources into one pup, as the energy she uses up during one breeding season negatively impacts on how she will cope with rearing subsequent pups. So this relationship between oxytocin and mass gain rates in pups may be important, as it would enable pups to get as big as possible before weaning without getting seal mothers to invest more energy in rearing them.

Yearling grey seals on the Isle of May in the summer. Surviving their first year at sea is tough for young seals.

It’s not just seals that would benefit from this hormone-development link in infants either. Oxytocin, or oxytocin like peptides, are present in every vertebrate animal group and their function is remarkably similar across all these different species. Infancy is a crucial time, and in all species, gaining mass and developing physically is vital for offspring to survive. In humans alone, problems with infant nutrition and development are estimated to cause 45% of deaths in children under five and if we can better understand the physiology underlying weight gain in infants, we have a better chance at developing ways to help those that are sadly failing to thrive. This work so far has shown that oxytocin release may connect optimal parental or social environments with direct advantages for infant development, which could be important for different fields of biological, medical and veterinary science, and I’m hoping to keep working on this phenomenon in the coming years.

The positive oxytocin feedback loop system in grey seal mother-pup pairs and the energetic dynamics in both individuals (from Robinson et al. 2019, Psychoneuroendocrinology, vol 110).

MEANWHILE I’ve had a baby! This is the reason that there haven’t been any updates for so long, I’ve been busy being a parent. I am still working on the PHATS project and my other research looking at oxytocin and social behaviour in mammals, but everything takes a lot longer now! I did get to go and present some of our findings at the Society of Experimental Biology conference in Seville over the summer, and we all had a great time making new science friends, hearing about amazing research and enjoying the Spanish sun. My daughter took the conference in her stride and I must say that the SEB were wonderfully supportive of me being there with a young baby. I will be writing another blog post soon about my great first experience going to a conference as a mother, especially as there are plenty of other conferences that are not doing such a good job and all the things the SEB did would work in other places. Being able to go to meetings like this makes such a difference to parents trying to get back into their careers after having a baby, so it is important for societies to include things like breastfeeding rooms and childcare options when they are planning conferences.

In the meantime, I will be working on more publications from the PHATS project and my oxytocin work plus grant applications so I can continue my research, so wish me luck and watch this space (or twitter) for updates!

My daughter enjoying her first conference and flying the flag for the PHATS team!

Attending Behaviour 2017 and other upcoming conferences

Hear about all the hormone, behaviour and adipose tissue function work I’ve done with seals at any of the three conferences I’m attending this year!

I’m going to Behaviour 2017 in Portugal next week!

Conference information: link

I’m going to be talking about my work on oxytocin and maternal and social behaviour in grey seals on monday afternoon, plus I’m presenting a poster on the development of aggressivness in seal pups on wednesday and thursday.

Symposium talk: Syposium 1 on Monday 31st July at 17:35 – 18:05

The symposium is titled ‘How Social Behaviour can impact individual health and fitness’. It will feature talks looking at how social living can impact on a range of aspects of an individual’s physiology, and the potential fitness costs and benefits associated with them. The talks cover primate species, fish and of course seals in my case!

Poster: Poster 278, Wed + Thurs, 2nd-3rd August 14:00 – 16:00

If you’re going to the conference and would like to find out more about my work it would be great to meet you there!

Please do say hello if you would like to talk to me about my research, my crazy ginger hair usually make me easy to find!

I’m also attending two other conferences this year, one to (hopefully) talk about my oxytocin work and the other to talk about the tissue culture work I’ve done

(TBC) Oxytocin work – 10th – 12th September
British Society for Neuroendocrinology, Nottingham (conference site: link)

Tissue Culture work – 22nd – 27th October
22nd Marine Mammal Biennial, Canada (conference site: link)
“An explant approach to understand adipose tissue function; metabolic profiles of blubber tissue differs between tissue depth, cell culture conditions and energetic state.”

So if you are attending either of these conferences you can catch me there too!

Safe travels!

New Publication – IV oxytocin causes pro-social behaviour in seals

Grey seals on the Isle of May, Scotland. Staying together is important for mother-infant pairs, especially on a dangerous seal colony.

Link to article: http://rspb.royalsocietypublishing.org/content/284/1855/20170554

Or read the summary here on this site.

This week has turned out to be a hectic but good one, I’ve returned from the University of Liege just in time for my next paper to be published in the Proceedings of the Royal Society B. The paper comes from the research in my NERC funded PhD with the Sea Mammal Research Unit, University of St Andrews on the hormone oxytocin and its impacts on social and maternal behaviour, rather than the pollutant research I’m currently doing with the PHATS team. Like much of my work, the study was done with weaned grey seal pups on the Isle of May, and involved giving the seals specially designed doses of oxytocin to see what (if any) social behaviours the hormone affected.

There have been lots of studies that show certain behaviours are linked to oxytocin concentrations (including some of my own grey seal work!), but the problem with correlations is that you have no idea which side of the relationship is driving things. For example, it would be impossible to tell using only correlations whether increased social behaviours are causing high oxytocin levels, or high oxytocin levels are triggering more social behaviours. Understanding causality in such hormone-behaviour relationships is important so you can identify the ‘cause’ and the ‘effect’ within the correlation. It can be difficult to do outside of laboratory settings however, as the only way to test for causality is to either increase the hormone’s concentration in an individual via manipulations or knock out the functionality of the hormone using antagonists. Due to these difficulties, there is only one study (apart from the one I published today) that has ever given oxytocin to wild individuals, and while they did find changes in pro-social behaviours they had no prior knowledge of the natural oxytocin-behaviour systems in their study animals.

We know high oxytocin grey seal mothers stay closer to their pups, but does the hormone cause the behaviour or does being near to their pup for more time cause greater oxytocin release?

In our study we were testing whether oxytocin triggers individuals to stay close to each other, as we know from grey seal mothers that the higher their oxytocin concentrations, the more time they spend close to their pups. We gave oxytocin and saline (control) treatments to weaned grey seals that had never previously met, and recorded their behaviours after the treatments. We found that oxytocin not only triggered individuals that had never met before to spend more time together, but also reduced aggression between the two and the amount the seals investigated each other, an indication of familiarity. This makes our study the first to verify a naturally existing oxytocin-behaviour relationship in wild individuals, which is very exciting. Studies like this have been done in captivity using domestic, laboratory or zoo animals but it’s crucial to study behaviour and physiology in natural settings with wild individuals, as no matter how hard you try you will never truly re-create all the complex aspects of wild environments in a captive setting.

Weaned grey seal pups associating on the Isle of May, Scotland

The treatments were all given intravenously (IV), as the more common, intranasal route of oxytocin manipulation was not possible with the weaned seal pups; they can close their nostrils and hold their breath for a long time! The success of this route of administering the manipulation means that other animal species, that may not be suitable for intranasal manipulations, could potentially have similar studies done on them in the future to help us understand more about oxytocin’s important role in bonding and behaviour. We also spent considerable effort designing the oxytocin dose given to the seals to be as low as possible while still having a behavioural affect. Many doses used in the scientific literature are much higher than natural concentrations, and there are concerns that generating high levels in study individuals could trigger behaviours that would never naturally happen, or have unexpected, and unwanted, side effects.

Weaned grey seal pups having a disagreement on the Isle of May. Reduction of aggression between familiar individuals happens naturally without oxytocin release in seals, but manipulations also trigger this behavioural change with seals that are complete strangers.

Despite the effort we went to in replicating natural oxytocin concentrations as much as possible for our study, the treatments still triggered some behaviours that are not naturally correlated to oxytocin release in seals. Low aggression and reduction of investigative behaviours are indications that seals recognise each other, and naturally occur after several days of living together, independently of oxytocin release. The behavioural changes in our study seals also unexpectedly persisted for several days, long after the dose would have been metabolised and broken down in the bloodstream. These unexpected effects show that we still have a lot to learn about oxytocin’s role in the formation and maintenance of social and parental bonds. If the hormone is going to be used to safely and successfully treat human psychological conditions such as schizophrenia, autism spectrum disorders and post traumatic stress disorder (and there have already been clinical oxytocin trials for such conditions in human subjects), then more research is needed into the powerful effects oxytocin can have on our behaviour and neurobiology.

Weaned grey seal pup on the Isle of May.