Researchers inhibited the effect of a hormone associated with aggression – the effect was the opposite of what was expected
How does our complex social behavior work? And how is it created and designed? These questions have occupied researchers for many years. In human society, as in the societies of other animals, there exist complex relationships of hierarchy, attraction and rivalry, and during evolution patterns of behavior developed that characterize and represent these relationships. Researchers who followed the brain activity of animals while they displayed certain patterns of behavior discovered that molecules passing between different areas of the brain, and between the brain and other organs in the body, participate in the decision-making in the brain and transfer the decisions made to the rest of the body for execution.
The chemistry of social behavior
One of these molecules is vasopressin. It is a hormone produced in the hypothalamus region of the brain and secreted from the pituitary gland into the bloodstream, affecting a variety of body functions and, among other things, preventing urination. Vasopressin also affects the working patterns of the brain itself, and binds to special receptors in the brain, which trigger different cell responses.
Previous studies have shown that the vasopressin hormone is involved in social behaviors such as showing aggression. Now a new study was conducted, the results of which were published in the scientific journal PNAS, in which the researchers examined in depth the role of this hormone in social behaviors. The study was conducted on golden hamsters (Mesocricetus auratus), known for their complex social behaviors, such as expressions of social hierarchy and communication through the distribution of scents. Hamsters are also similar to humans in their stress response, which, like ours, is accompanied by the secretion of the hormone cortisol. Thanks to these properties, golden hamsters are often used in behavioral experiments that study the interactions between the nervous system and the endocrine system.
In the new study, the researchers created through genetic engineering hamsters whose brains lack the receptors that enable the sensing of vasopressin. Then we looked at how the absence of these receptors would affect the social behavior of the hamsters.
A hormone produced in the brain and secreted into the bloodstream, also affects the brain itself and social behaviors. Vasopressin molecule Bacsica, Shutterstock
A surprising effect
The results of the study were surprising. The researchers hypothesized that if vasopressin is necessary for the existence of social action patterns, the deletion of the receptor that identifies it will result in a decrease in the social communication that the animal will demonstrate. In practice, the hamsters who could not sense vasopressin actually demonstrated higher levels of social communication through odors than normal hamsters. The transgenic hamsters were also more aggressive.
The surprising findings remind us that we are far from knowing everything. It is possible, for example, that vasopressin does encourage social behavior in certain areas of the brain, but in other areas it suppresses it. The scientific understanding of social activity, and of animal behavior in general, has advanced greatly over the years, but there are still large gaps in knowledge. The researchers in the field are currently planning the following studies, which may provide us with new findings and conclusions. When these studies deepen our knowledge, we may be able to apply them to the treatment of various types of behavioral disorders.