Effects of Social Isolation and an Enriched Environment on Anxious-Depressive Behavior in Rats in Normal Conditions and after Early Proinflammatory Stress

Effects of Social Isolation on the Development of Anxiety and Depression-Like Behavior in Model Experiments in Animals

“…This behavior was not seen in males. We did not see any signifi cant differences in anxiety levels between males and females which had been in SI, though they had higher anxiety indicators than control animals [Pavlova et al, 2021]. Similar results were obtained by Caruso et al [2017]; in their experiments, repeated episodes of isolation of ALB/cJ mice in adolescence alternating with social novelty for four weeks increased anxiety in males and females, while depression-like behavior was seen only in females.…”

“…Depressionlike behavior in the FST at week 12 of life was seen only in females, not in males. In our study [Pavlova et al, 2021], we also observed depression-like behavior in the sucrose preference test only in females exposed to SI from day 45 to day 105 of life, though the effect of isolation was clearly apparent only in combination with early proinfl ammatory LPS stress. This behavior was not seen in males.…”

“…The basal corticosterone level after nine months of SI was no different from the corticosterone level in control animals, though it was higher in females than males regardless of housing conditions [Krupina et al, 2020]. In our study [Pavlova et al, 2021], a signifi cant increase in the corticosterone level was seen in all groups of rats after two months of SI, which is evidence of their greater reactivity to stressors (FST) as compared with the control group.…”

“…The sucrose preference test in rats in social isolation produced signs of depression-like behavior only in females, in groups which had and had not received additional neonatal LPS stress, the latter showing a tendency to differences from control animals. In the FST, isolation did not lead to any increase in hanging time in either males or females, i.e., this test revealed no signifi cant differences in the level of depression-like behavior [Pavlova et al, 2021]. Differences in the effects of SI were found depending on test type and mouse strain [Voikar et al, 2005].…”

“…Of particular signifi cance among these are the duration of isolation and the age at which it started. Among other causes factors affecting behavior in SI conditions are sex (see below), animal species (results in rats and mice in SI are different), and rat strain [Painsipp et al, 2011], the nature of the models used and the equipment involved (for example, the designs of the OF and EPM) [Pavlova et al, 2021], and a number of others.…”