Research carried out at the University of Oviedo has concluded that animal husbandry and breeding conditions determine brain development and behaviour in the adult stage. The study reveals that young animals raised in an enriched environment –a more positive environment in principle, with a greater number of animals per large box, a greater level of sensory stimulation and physical exercise– instead showed greater impulsiveness and anxiety among adults and, therefore, less resilience to stressful situations. 

 

The work, whose results have come to light in the PLOS ONE journal, highlights the need for the current European regulations on the care of experimental animals, dating from 2010, to specify what these enriched environment conditions should be, which until now have been required without specificity, since in this study they were negative for animal welfare. In this sense, Héctor González Pardo, Professor of Psychology and Psychobiology researcher, who led the research, says to "standardise or specify the optimal or valid procedures of said environmental enrichment in order to guarantee the validity of the experiments and, especially, the animals' welfare". 

 

Regarding the possible causes of the negative effects found in this work, González Pardo points out that "living with a large number of animals (10) in this complex environment probably generated psychosocial stress for all the animals (regardless of the previous maternal separation), since a social hierarchy of dominance is established in the group (the same as in primates and human beings)." 

 

The study was undertaken by the University of Oviedo by researchers from the Asturias Principality Institute of Neurosciences, INEUROPA, mostly also belonging to the NEUROCON Health Sciences Research Group. 

 

Maternal separation models

 

The work also revealed that the animal model of exposure to early psychosocial stress by daily separation of young rats from their mothers for a few hours did not produce adverse consequences on behaviour, as initially expected, but also on metabolism brain measured in various regions involved in this behaviour. The animals showed no learning or spatial memory problems or behaviour similar to depression in adulthood, and even had less anxiety in standardised tests. 

 

The results could partially be explained by a resilience or adaptation effect to stress through biological mechanisms (neuroendocrines) during their development since childhood, but also by an environmental effect modulating stress, by increasing compensatory type maternal care in these animals under stress. 

 

The purpose of these maternal separation models is to reproduce or model the consequences of early psychosocial stress in humans, for example, neglect in parental care, emotional and/or physical abuse, and so on. These are factors that have been shown to predispose the future development of various mental disorders during childhood, youth and adulthood, such as anxiety disorders, depression, drug addiction and even schizophrenia. 

 

DOI

 

https://doi.org/10.1371/journal.pone.0226377