NEUROBIOLOGICAL CONSEQUENCES OF CHRONIC SLEEP LOSS: HIPPOCAMPAL NEURONAL PLASTICITY AND BDNF SIGNALING

Frequently disrupted and restricted sleep is a common problem in Western societies and may, over time, impair health and increase vulnerability to psychiatric disorders. Sleep is critical for synaptic plasticity across brain systems, with the hippocampus appearing particularly sensitive to sleep loss. In mice, acute sleep deprivation (SD) induces cognitive impairments alongside reductions in dendritic spine density and dendritic length in the hippocampus. In rats, one month of sleep restriction (SR) has been linked to hippocampal volume reductions of up to 10%. A proposed mechanism underlying these effects is the downregulation of brain-derived neurotrophic factor (BDNF), which is frequently observed in both chronic SD and depressive disorders. However, it remains unclear whether reduced neurogenesis and/or dendritic spine loss fully explain hippocampal atrophy following chronic SR.

To address this, we used an animal model to examine the effects of prolonged sleep loss on neuronal plasticity and BDNF signaling in the dorsal hippocampus. Adult Sprague–Dawley rats were subjected to chronic partial SD for 34 days, with sleep limited to 4h per day using slowly rotating drums. After the experimental period, brains were collected and hemispheres separated. One hemisphere was processed for Golgi staining to assess dendritic length and spine density in dorsal hippocampal neurons, while the other was used for Western blot analysis of neuronal plasticity markers. Plasma BDNF levels were measured using ELISA.

This study aims to clarify the impact of chronic SR on hippocampal plasticity and BDNF, advancing understanding of the neurobiological mechanisms underlying sleep loss–related hippocampal shrinkage.