Impact of Sensory Contact Model on Psychosocial Stress and Correlation with Immunological Changes

Abstract

Background and objectives: Chronic stress plays a central role in the pathogenesis of psychiatric disorders. A sensory contact model induces mixed anxiety/depression-like behaviors. Repeated experience of victories or defeats may change neurophysiological status, the immune system and brain neurochemistry in opposite directions. The objective of this study was, therefore, to establish a sensory contact model for studying the impact of psychosocial stress in mice and investigate its influence on behavioral, neurochemical and immunological changes of both winners and losers. Methods: Four groups of male mice were used, including two groups that received saline and either in normal housing or caged individually for 5 days; the others were subjected to sensory contact modeling for 21 days. All mice were subjected to open-field test, after which blood samples were collected for evaluation of total and differential leukocyte count and brain homogenate was used to estimate monoamines. Results: Social isolation reduces serotonin and neutrophils while elevating most other parameters. Winners also showed reduction in serotonin and neutrophils, as compared to controls which showed reduction in grooming time, total leukocyte count, neutrophils associated with elevation in monocytes and eosinophils as compared to isolation group. On the other hand, losers showed elevation in grooming time, dopamine, norepinephrine, lymphocytes, monocytes, eosinophils associated with reduction in ambulation, serotonin and neutrophils as compared to all groups. They also showed reduction in rearing and elevation in total leukocyte count as compared to winners. Conclusions: Social stress leads to severe depression and anxiety-related behaviors; losers were more depressed than winners. However, aggressive behavior was increased in winners, while locomotor and exploratory activities were decreased, indicating decreased anxiety and emotional distress. The immune function was enhanced to higher extent in losers than winners, which can be attributed to sensation of threat and trauma in losers.

Short-Term Relocation Stress-Induced Hematological and Immunological Changes in Saimiri boliviensis boliviensis

“…The squirrel monkeys were still affected by the relocation process days after relocation and probably should not be considered acclimated to their new social environment. The effect of social stress includes impaired cellular immunity demonstrated by increased lymphocyte counts and decreased lymphocyte proliferation in response to phytohemagglutinin, as observed in cynomolgus monkeys [ 46 – 48 ].…”