Stress resilience evidenced by grooming behaviour and dopamine levels in male mice selected for high and low immobility using the tail suspension test

• Published in: The European journal of neuroscience Vol. 50; no. 6; pp. 2942 - 2954
• Main Authors: Reis‐Silva, Thiago M., Sandini, Thaisa M., Calefi, Atilio S., Orlando, Bruna C. G., Moreira, Natalia, Lima, Ana Paula N., Florio, Jorge C., Queiroz‐Hazarbassanov, Nicolle G. T., Bernardi, Maria Martha
• Format: Journal Article
• Language: English
• Published: France Wiley Subscription Services, Inc 01.09.2019
• Subjects: behavioral selection; brain structures; catecholamine; Corticosterone; Dopamine; Dopamine receptors; Drug screening; environmental stress; Grooming; Hypothalamus; Mesencephalon; Mesolimbic system; Phenotypes; Prefrontal cortex; Sucrose; environmental stress; catecholamine; behavioral selection; brain structures
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.14409

Grooming behaviour has different functions on many species during development and can be observed and affected during periods of stress. By selecting male mice with high (HI) and low (LI) immobility traits in the tail suspension test, a screening for antidepressant drugs, we investigate how these phenotypes associated with grooming behaviour may be influenced by the effects of repeated restraint stress. For this we used the sucrose preference test and the splash test in a novel and a familiar cage performed before and after exposure to 2 days of restraint stress. Animals were submitted to an additional day of restraint stress before the hypothalamus, prefrontal cortex and midbrain extraction for dopamine activity analysis. Corticosterone analysis was made in three distinct moments: without stress (prior first restraint session), immediately after the last restrain, and 1 hr after the last restrain episode. Compared to LI group, HI animals exhibited an increased frequency and decreased time of grooming in the familiar cage. In the novel cage, stress increased frequency and time of grooming of HI animals compared to LI. Corticosterone levels were increased in HI animals after 3 days of stress. Lower hypothalamic dopaminergic activity without stress and decreased hypothalamic dopaminergic activity immediately after stress in HI group were observed. The HI group displayed decreased prefrontal cortex dopaminergic activity and increased activity in the mesolimbic area. We proposed that through the influence of stress the two phenotypes manifested as a resilient (LI) and a not resilient (HI) trait in response to restraint stress. Restraint stress resilience exhibited by male mice selected for high (HI) and low (LI) immobility in the tail suspension test. Behavioural results revealed increased frequency and decreased time of grooming of HI mice in the splash test with differences in a new and familiar cage environment before and after stress. Increases in corticosterone as lower hypothalamic dopaminergic activity without stress and decreased after three days of stress in HI mice were also observed.