Early life stress is known to influence affective and cognitive functions in later life but comprehensive explanation for the impact of early life stress on attentional functions, behavioural control and social behaviour is inadequate. The early life stress was induced by exposing rat pups to 6 h of maternal separation and isolation (MS) stress from postnatal days 4-14 i.e. during SHRP period. The long-term impact of MS in these rats was evaluated by assessing anxiety, sociability, social preference, spatial learning and memory along with a detailed evaluation of attentional functions during young adulthood period. Adult male MS rats showed increased anxiety-like behaviour, impaired flexibility in social interactions, and increased reward-seeking behaviour. MS rats also showed faster spatial learning in the partially baited radial arm maze and exhibited moderately enhanced sustained attention in the 5-choice serial reaction time task (5CSRTT). These results suggest that early MS has both positive and negative consequences in adulthood. Increased cognitive ability in MS rats, as evidenced by the improved sustained attention and spatial learning and memory, is usually advantageous and indicates positive influences of early stressors that might lead to the development of resilience and enhanced compensatory mechanisms later in adulthood. MS stress has compromised flexibility in social behaviour that promotes solitary lifestyle and social isolation. Heightened reward-seeking behaviour, as shown by the MS rats, could be a predisposing factor for substance abuse and addiction. Thus, our study highlights the crucial and differential impact of early life challenges on behaviour during adulthood and suggests that the positive aspects could be an asset that may be utilized to suppress the negative effects of early life stress in adulthood.
Keywords: 5-Choice serial reaction time task (5CSRTT); Anxiety; Cognitive flexibility; Learning and memory; Maternal separation stress (MS); Perseveration; Sustained attention.