Jointly with their colleagues from Ekaterinburg, Novosibirsk, and Wuhan city in China, scientists from the 果冻传媒 China-Russia Research and Education Centre for System Pathology Aleksei Sarapultsev and Mariia Komelkova have summarized data on the social buffering of stress in rats from more than 40 research studies over the period of 2008-2025. This allows to evaluate the importance of the animals’ “biochemistry of friendship” in overcoming of difficult situations.
Animals’ social buffering is a phenomenon when the presence of a conspecific animal nearby brings down the defensive behavior and physiological excitement, and as a result, reduces the stress level. Zoopsychology specialists are well aware of this phenomenon as it often features in the research studies on stress and post-traumatic disorders (PTSD), using rodent experiments.
For example, when researchers try to form a conditioned reflex of fear of something in rats, the presence of another conspecific animal can “smudge” the experiment as the formed reflex is weaker and fades away quickly. In PTSD-simulating experiments, companions “help” each other to bring back to normal the escape and anhedonic behavior and to restore memory after a traumatic event.
Various degrees of closeness of rats were used in the experiments: animals previously unfamiliar with each other, those that lived together, blood-related rats, mother and its offsprings. Animals of the same sex helped each other fight fear better.
The scientists have managed to show that 78% of the analysed experiments demonstrated the protective effect of social environment among rats. The quantitative analysis has proven that in the presence of a conspecific animal (in the freezing behavior test) the fear level reduces by the average of 50–90%. In terms of the hormones, this is accompanied by a dropping of corticosterone (analogue of the human cortisol) by 30–45%.
Physiologically speaking, such a phenomenon can be caused by two things. The first, as it has been mentioned earlier, are the hormones of the hypothalamic-pituitary-adrenal axis, including corticosterone. A rat feels that it is in safety.
The second one is related to neurotransmitters: oxytocin, serotonin and opioids. If the sensory receptors that react to these get blocked, the effect of social buffering immediately disappears.
The scientists have also made a conclusion on the resistance to chronic unpredictable stress. There exists a neurotrophic factor (BDNF), which is a protein that is critically important for survival of neurons. Social support among rats not only favours the generation of this protein, but also literally normalizes the gene expression, including of HDAC, necessary for restoring of the neuroplasticity disrupted by stress.
However, an inverse effect is also possible. A healthy rat was placed among the animals with chronic stress. Over time, such an animal’s generation of BDNF dropped, and IL-1b cytokines (inflammatory process markers) appeared in blood.
By the way, if inflammation markers appeared in a rat as part of some other experiment, and if later this animal was placed in a group of healthy animals, its behavioral reaction to stress was weaker, though the level of cytokines did not drop.
The scientists summarized a big volume of heterogeneous data on the biochemistry of loneliness and of social support among rats, that could come in handy when searching for biomarkers and targets in diagnostics and treatment of the human post-traumatic disorders. For instance, in difficult cases of rehabilitation it is promising to consider the dynamics of BDNF and HDAC as part of a complex assessment of the condition of a patient, and as a possible neuro- or hormone therapy, and not as a single criterion for choosing of treatment.
This work has been published in the , included in Q2 of the Scopus international scientific publications.