Overview

• University of Coimbra researchers report that brief exposure elicited anxiety-like responses, whereas prolonged mild unpredictability aligned with depressive-like signs.
• Male rats showed the strongest anxiety-like effects after brief stress, underscoring pronounced sex-dependent responses.
• Biochemical analyses found alterations in key blood–brain barrier proteins that varied by sex following both exposure types.
• Open field and forced-swim tests in male and female Wistar rats assessed locomotion along with anxiety-like and depression-like behaviors.
• The study appears in Behavioural Brain Research (DOI: 10.1016/j.bbr.2025.115706), received support from the BIAL Foundation, and is framed as preclinical context alongside WHO data on the global mental health burden.