Preoperative recovery sleep ameliorates postoperative cognitive dysfunction aggravated by sleep fragmentation in aged mice by enhancing EEG delta-wave activity and LFP theta oscillation in hippocampal CA1

• Published in: Brain research bulletin 2024-06, Vol.211, p.110945-110945, Article 110945
• Main Authors: Li, Yun, Hou, Shaowei, Li, Feixiang, Long, Siwen, Yang, Yue, Li, Yize, Zhao, Lina, Yu, Yonghao
• Format: Article
• Language: English
• Subjects: Aging - physiology; Animals; CA1 Region, Hippocampal - physiopathology; Cognitive Dysfunction - etiology; Cognitive Dysfunction - physiopathology; Delta Rhythm - physiology; Delta wave; Electroencephalography; Electroencephalography - methods; Hippocampus; Local field potential; Male; Mice; Mice, Inbred C57BL; POCD; Postoperative Cognitive Complications; Recovery sleep; Sleep - physiology; Sleep Deprivation - complications; Sleep Deprivation - physiopathology; Sleep fragmentation; Theta oscillation; Theta Rhythm - physiology
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/j.brainresbull.2024.110945

Sleep fragmentation (SF) is a common sleep problem experienced during the perioperative period by older adults, and is associated with postoperative cognitive dysfunction (POCD). Increasing evidence indicates that delta-wave activity during non-rapid eye movement (NREM) sleep is involved in sleep-dependent memory consolidation and that hippocampal theta oscillations are related to spatial exploratory memory. Recovery sleep (RS), a self-regulated state of sleep homeostasis, enhances delta-wave power and memory performance in sleep-deprived older mice. However, it remains unclear whether RS therapy has a positive effect on cognitive changes following SF in older mouse models. Therefore, this study aimed to explore whether preoperative RS can alleviate cognitive deficits in aged mice with SF. A model of preoperative 24-h SF combined with exploratory laparotomy-induced POCD was established in 18-month-old mice. Aged mice were treated with preoperative 6-h RS following SF and postoperative 6-h RS following surgery, respectively. The changes in hippocampus-dependent cognitive function were investigated using behavioral tests, electroencephalography (EEG), local field potential (LFP), magnetic resonance imaging, and neuromorphology. Mice that underwent 24-h SF combined with surgery exhibited severe spatial memory impairment; impaired cognitive performance could be alleviated by preoperative RS treatment. In addition, preoperative RS increased NREM sleep; enhanced EEG delta-wave activity and LFP theta oscillation in the hippocampal CA1; and improved hippocampal perfusion, microstructural integrity, and neuronal damage. Taken together, these results provide evidence that preoperative RS may ameliorate the severity of POCD aggravated by SF by enhancing delta slow-wave activity and hippocampal theta oscillation, and by ameliorating the reduction in regional cerebral blood flow and white matter microstructure integrity in the hippocampus. •Preoperative recovery sleep alleviated postoperative cognitive performance by improving hippocampal perfusion and microstructural connectivity and integrity.•NREM sleep and delta wave power increased during recovery sleep following SF preoperatively.•Preoperative recovery sleep improved hippocampal CA1 theta oscillation in Y-maze task.