0081 The impact of sleep deficiency on spatial working and long-term memory in different rat models of sleep deprivation

Abstract

Abstract Introduction A pressing issue in modern society, lack of sleep has detrimental health consequences, among which cognitive dysfunctions attract great attention. Although there is consensus about the harmful effects of insufficient sleep on vigilance and attention, there is still a debate about memory susceptibility to acute and chronic sleep deprivation. Which types of memory are more vulnerable remains unclear. We studied the susceptibility of spatial working and long-term memory to acute and chronic sleep deprivation in rats. Methods Male Wistar rats were deprived of sleep (SD) by placing cages on an orbital shaker. Animals were subjected to three patterns of SD: 1) acute SD (ASD) — continuous SD for 18 hours; 2) short sleep restriction (SSR) —cycles of 3-hour SD followed by 1 hour of sleep opportunity over 24 hours, with a total SD duration of 18 hours; 3) chronic sleep restriction (CSR) — SSR for 5 consecutive days. For each SD protocol, working spatial memory was assessed with the spontaneous alternation test in the Y-maze. Learning and long-term spatial memory were assessed in the Barnes maze test. Results ASD impaired spatial working memory, as assessed by spontaneous alternations in the Y-maze test, and decreased the level of locomotion/exploration (assessed by the number of arm entries). However, in SSR and CSR, 1-hour alternating sleep opportunities allowed for preventing working memory loss. The Barnes maze test demonstrated no changes in learning or spatial long-term memory under any tested SD conditions. Conclusion The results suggest that spatial working memory is the most vulnerable to continuous sleep loss. Even under a 5-day chronic sleep restriction, the negative effect disappears if rats are allowed to sleep during intermittent 1-hour intervals. It indicates the great importance of short sleep intervals that protect memory against sustained sleep restriction. The resilience of long-term memory to any of the tested sleep deprivation conditions implies that short-term and long-term memory systems diverge in their susceptibility to sleep deficiency. Support (if any) State assignment to the Institute of Evolutionary Physiology and Biochemistry; theme reg. no. АААА-А18-118012290427-7.