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BBB Seminar: Janne Grønli

Lifetime consequences of maternal separation – behaviour, sleep, circadian rhythms and brain activity

Janne Grønli
Department of Biological and Medical Psychology, University of Bergen, and
Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen

Negative childhood experiences, such as abuse, neglect or loss of a parent, may bring a life-long burden of behavioural and pathophysiological problems. The risk for sleep disturbances and later emotional problems are widespread and prevalent. For many species the environment in which they develop is of crucial importance for how they develop, the brain especially. Negative and stressful maternal regulatory input can induce long-term alterations in behavioural and neurobiological systems.

To model the powerful effects of negative early life experiences lasting the entire life span and influencing the brain, sleep, circadian rhythms, behaviour and risk for mental disorders, we combined maternal separation with mild uncontrollable challenges in adult life. Rat pups were subjected to daily separation from the dam during postnatal days 2-14 for either180 min (long maternal separation; LMS), 10 min (brief maternal separation; BMS) or undisturbed (non-handled; NH). N=20 in all groups. At postnatal day 90 half of the animals within each group were exposed to 4 weeks of chronic mild stress (CMS), while the remaining animals were left undisturbed during the same period. Prior to CMS exposure, 8 LMS-CMS and 7 BMS-CMS animals were implanted with a subcutaneous telemetric device for electroencephalographic (EEG), electromyographic (EMG) and peripheral body temperature measurements.

Long maternal separation induces reduced body weight and lower brain activity (EEG power density) during wakefulness, slow wave sleep and REM sleep. This effect was potentiated by CMS. Long maternal separation offspring showed also a vulnerability to later life challenges with reduced body weight gain, increased plasma corticosterone, reduced preference for sucrose (anhedonia-like measurement in rodents), lower body temperature, increased total sleep time, and REM sleep changes. Brief maternal separated offspring seem more robust to handle chronic stressors as adults. Normal body weight gain, no change in plasma corticosterone, no changes in preference for sucrose, only transient changes of body temperature and no sleep changes were found after CMS. Non-handled offspring seem also vulnerable to later life stress. An increased plasma corticosterone and less preference for sucrose were found.

Long maternal separation results in lower brain activity and a weakness in handling challenges in later life.

Host: Boleslaw Srebro, Department of Biomedicine