S u m m a r y: The love hormone oxytocin might be behind the courage of parents who are willing to sacrifice their lives to protect their offspring if the need arises, suggests new research published in the journal eLife.
A parent’s heart is unlike others’
While the animal (and human) instinct is to run (or freeze!) when faced with danger, parents behave in a very different way in this situation when their young are with them. W h y? Why do mothers and fathers risk their own lives to protect that of their child? Apparently, it is all about the love hormone, known as oxytocin, says the new research, conducted by a team of neuroscientists from the Champalimaud Centre for the Unknown, in Lisbon, Portugal.
Run or face danger: Love hormone decides!
The radical shift in behaviour, from protecting oneself to shielding one’s young, is based on the action of love hormone oxytocin, a molecule which plays a crucial role in social bonding, including the relationship between mothers and their babies as well as within couples. So, this hormone appears to trigger the parental protective response through its action on brain neurones found in a specific structure called the amygdala which is known to be involved in the processing of emotions. The influx of oxytocin into this part of the brain inhibits the basic self-defense reaction whereby one just freezes upon spotting a threat; animals normally use this to evade danger, they remain motionless to avoid being seen by predators.
Love molecule vs self-defense
It is to be noted that the functions of oxytocin are, otherwise, not well understood. Scientists have been attempting to unravel the mystery surrounding this hormone, but, so far, this has proved to be challenging. The new findings, thus, come in handy to understand one aspect of it: oxytocin’s inhibition of a self-defense mechanism.
Lead author of the paper, Marta Moita, explains that they have devised an experiment to study the defensive behaviour of a mother rat both in the presence and absence of her pups while simultaneously monitoring the action of oxytocin in the amygdala. According to Moita, the team surpassed the normal limitations of studies on oxytocin (resulting from the multi-action of the hormone on several areas of the hormone) by manipulating a circuit where they could point out precisely how the love hormone inhibited freezing. She adds that they are very confident of their interpretation of their results.
The experiments consisted in conditioning the mommy-rats to link a peppermint scent with imminent danger (of a harmless electric shock). This was done in the absence of their babies. Thereafter, whenever the rats would sense the scent, they would freeze. However, in the presence of their babies, the mommy-rats would not freeze: rather, they would protect their pups from the peppermint odour, and attack its source (a tube from where the scent was coming). The mother-rats would also attempt to obstruct the tube by putting in materials from their nest into it. For older pups, the mothers would nurse and groom them, all the while keeping them close.
Now, to test whether oxytocin was really responsible for this shift in behaviour, the scientists blocked its activity in the mother rats’ amygdalas. When this happened, the mothers would freeze upon perceiving the threat, regardless of the age of their pups. They had deviated from their usual maternal behaviour.
The findings, thus, show that love hormone oxytocin triggers the defensive mechanism in mothers to shield their young.
Similar mechanisms might be driving humans to take to the parent-defends-young behaviour, according to Moita.