To this note, Professor Daniela S. Rivera from Universidad Mayor, Carolina B. Lindsay from Universidad de Chile, Dr. Carolina A. Olivia from Universidad Andres Bello, in collaboration with Professor Francisco Bozinovic and Professor Nibaldo Inestrosa C. from the Pontificia Universidad Catolica de Chile investigated the long-term effects of chronic social isolation stress on the behavior of degus (Octodon degus)as a model, which was published in the Neurobiology of Stress journal.
Professor Rivera and colleagues used novel object open-field and light-dark box testing to evaluate the impact of long-term chronic social isolation stress on anxiety in male and female degus, as they share similar genetic and physical characteristics with humans. Open-field testing was a primary screening for anxiety in rodents as it measures novel environment exploration and general locomotor activity. The light-dark box testing was used to measure the tendency to avoid stressful circumstances by using the number of light/dark transitions made by the subjects.
Their research showed that male degus showed insecurity and female degus showed hesitation to venture into dark transitions, thereby confirming the diurnality of these communal animals.
Led author Professor Rivera said: “For the first time, we evaluated behavioural responses to anxiety and social-related tests, and the profile of some brain-related proteins in adult, female and male individuals previously subjected to long-term chronic social isolation stress from post-natal and post-weaning until adulthood.”
Later, they observed that re-socialization after chronic social isolation brought in marked physiological, functional, and molecular modifications in memory-related tasks. In addition, the research team showed that associate behavioral outcomes like social memory would be impacted by social isolation in Octodon degus. They also evaluated the effect of long-term chronic social isolation stress on oxytocin levels pathways in the hippocampus, prefrontal cortex, and hypothalamus and if re-socialization would revert its effects. The involvement of the oxytocin levels pathway in the stress response of animals is governed by integrative networks at different molecular phases. Long-term chronic social isolation stress disrupts the oxytocin levels pathway. The researchers also observed the impairment of the HPA axis negative feedback loop and the cognitive defects associated with chronically stressed animals; male degus showed superior synaptic transmissions than chronically stressed female degus.
This extensive study confirmed that long-term chronic social isolation stress leads to impaired social memory and causes modifications in sociability—the observed permanent molecular changes in the oxytocin levels pathways caused by long-term chronic social isolation stress. As a result, male and female degus show different homeostatic mechanisms to process chronic social solution stress. They concluded that re-socialization can revert alterations in the behavior but could not regulate the oxytocin levels pathways in the social domain regions of the brain.
“Our study provides a comprehensive view of the effects of stressful conditions and its consequences on highly social animals. More importantly, we demonstrate that re-socialization plays a significant role as a buffer for stressful situations, normalizing behaviour” said Professor Rivera.
In summary, Professor Rivera and colleagues offer a view of how social animals process stressful conditions. It also indicates that re-socialization serves as a buffer for stressful situations. Findings from this critical study will guide future studies on the impact of re-socialization concerning humans.
Journal Reference and Main image Credit: Rivera, Daniela S., Carolina B. Lindsay, Carolina A. Oliva, Francisco Bozinovic, and Nibaldo C. Inestrosa. ““Live together, die alone”: The effect of re-socialization on behavioural performance and social-affective brain-related proteins after a long-term chronic social isolation stress.” Neurobiology of stress 14 (2021): 100289. https://doi.org/10.1016/j.ynstr.2020.100289
Dr. Daniela S. Rivera – Biologist, Ph.D
Dr. Daniela S. Rivera – Biologist, Ph.D. in Biology majoring in Ecology, Assistant professor at the GEMA Center for Genomics, Ecology & Environment, at the Universidad Mayor. Her research engaged in an interdisciplinary approach between behavior ecology, ecophysiology, neurobiology, and microbiology (particularly gut microbiota). Her work focuses on assessing how the effects of variation in environmental factors, such as diet, thermal fluctuations of the environment, early life stress, and social ties or lack of them, are correlated with changes in gut microbial communities, ultimately affecting host behavior patterns (i.e., social and foraging behaviors) and physiology. This multidisciplinary approach is critical to understand the functioning of nested ecosystems and further understand how the microbiome modulates behavioral and population patterns at the level of the host, such as foraging behavior or the development of behavioral disorders. Her research combines a wide array of techniques (field and laboratory studies of animal behavior) and spans molecular and cellular gut analysis, immunity, meta-genomics, physiology, and evolution. She has experience with several animal models such as insects, amphibians, lizards, snakes, and small mammals.
Dr (c) Carolina Lindsay Brain – PhD student
Dr (c) Carolina Lindsay Brain – PhD student at the Doctoral Program in Biomedical Sciences at the Universidad de Chile. She finished her undergraduate studies in 2017 together with obtaining a master’s degree in Biochemistry with her research focused on the study of the behavior and neurobiology of age-related cognitive impairments in Octodon degus. Her current line of research aims to elucidate the electrophysiological mechanisms underlying active visual perception, displayed by temporally precise motor modulation over layer specific-spikes and – field potentials of the primary visual cortex during free-moving tasks. In addition to her studies, Carolina has participated as evaluator and professor at the Faculty of Medicine of the University of Chile, together with several educational initiatives with children and adolescents within the Centre of Aging and Regeneration, the Institute of Biomedical Neuroscience and the EXPLORA Program.
Dr. Carolina A. Oliva – Biologist, Ph.D. in Neuroscience
Dr. Carolina A. Oliva – Biologist, Ph.D. in Neuroscience, Research Scientist, Biophysicist with vast experience in electrophysiology. Her work focus on some of the most socially relevant diseases, such as neurodegenerative diseases, which are correlated with the degeneration of specific circuits in the brain, causing emotional disturbances and cognitive impairments that progressively worsen until death. She uses in vitro and in vivo models that can generate different types of oscillatory activity circuit-specific, to investigate at the level of cells, circuit, and neuronal networks, the progression of major neurological diseases and to predict if some brain circuits are more susceptible than others to suffer neuronal dysfunctions. To study synaptic transmission and integration, she combines electrophysiological recordings of multiunit activity, the single-recording of cortical neurons, and the microscopic imaging of synaptic terminals and dendritic spines, to visualize the activity of cellular ensembles along different postnatal ages. The study of the protein expression pattern, such as pro-inflammatory molecules in a specific region, or metabolic products released in an activity-dependent form such as the subtypes of amyloid-β peptides, are used to complement the complex features of these diseases. She has vast experience in animal models, from flies to rodents like mice, rats, and degus.
Dr. FRANCISCO BOZINOVIC – Full Professor
Dr. FRANCISCO BOZINOVIC – Full Professor at the Pontificia Universidad Católica de Chile. Principal Researcher and Deputy Director of the Center for Applied Ecology and Sustainability. He is also Deputy Director of the UC-Down Syndrome Center. His line of research focuses on the area of Integrative Biology, which brings together a diversity of disciplines that complement each other to unravel the complexities and the diversity of biological systems. He works with types of organisms and levels of biological integration ranging from molecules to biological communities. Author of more than 300 mainstream scientific articles and 5 books in his specialty and outreach books for children. He is member of the Chilean Academy of Sciences and the Latin American Academy of Sciences, received grants, awards and scholarships from the University of Chile, the Andes Foundation (Chile), the Carnegie Museum of Natural History (USA) and the J. S. Guggenheim Foundation (USA). In addition, he won the Scopus-Elsevier award, the Medal of Scientific and Cultural Merit of the Croatian community, the Excellence Award of the Ecological Society of Chile, and the Atenea Award from the University of Concepción, among others. He was awarded the degree of Doctor Honoris Causa by the Universidad Austral de Chile and in 2020 he received the National Award of Natural Sciences
Dr. Nibaldo C. Inestrosa – Full Professor
Dr. Nibaldo C. Inestrosa – Full Professor of the Pontifical Catholic University of Chile and Director of the Center for Aging and Regeneration (CARE) in Santiago, Chile focused on the study of innovative therapeutic approaches to fight Alzheimer´s Disease and related chronic disorders. Dr. Inestrosa is an expert on the field of Neurobiology with a special interest on Neurodegenerative Diseases such as Alzheimer’s Disease and its relationship with the Wnt Signaling Pathway. He is also Director of the Center for Excellence in Biomedicine of Magallanes, Punta Arenas, Chile. He is author of around 370 scientific publications in prestigious scientific journals and directed 34 PhD thesis and 38 undergraduate theses. The citation of his work is nearly 26,105, with and H index of 86 (Google Scholar), in 2008 he was awarded the National Prize in Natural Sciences in Chile.