1Laboratory of Neurobiology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou   730000, Gansu Province, China

2Department of Neurology, Anning Branch of Lanzhou General Hospital of Lanzhou Military Area Command of Chinese PLA, Lanzhou   730070, Gansu Province, China

3Department of Anal-Rectal Surgery, Gansu Province Hospital, Lanzhou   730000, Gansu Province, China

Chunmin Zhu★, Studying for master’s degree, Laboratory of Neurobiology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou  730000, Gansu Province, China Supported by: the National Natural Science Foundation of China, No.30670677* Zhu CM, Yao XR, Zhang WS, Song YF, Hou YP. Progressive paradoxical sleep deprivation impairs partial memory following learning tasks in rats. Neural Regen Res 2008;3(6):598-603

Abstract

BACKGROUND: Complex learning tasks result in a greater number of paradoxical sleep phases, which can improve memory. The effect of paradoxical sleep deprivation, induced by “flower pot” technique, on spatial reference memory and working memory require further research.

OBJECTIVE: To observe the effect of progressive paradoxical sleep deprivation in rats, subsequent to learning, on memory using the Morris Water Maze.

DESIGN, TIME AND SETTING: Controlled observation experiment. The experiment was performed at the Laboratory of Neurobiology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Lanzhou University from December 2006 to October 2007.

MATERIALS: Twenty-eight, male, Wistar rats, 3–4 months old, were provided by the Experimental Animal Center of Lanzhou University. The Morris Water Maze and behavioral analyses system was purchased from Genheart Company, Beijing, China.

METHODS: All animals, according to a random digits table, were randomly divided into paradoxical sleep deprivation, tank control, and home cage control groups. Paradoxical sleep deprivation was induced by the “flower pot” technique for 72 hours, housing the rats on small platforms over water. Rats in the “tank control” and “home cage control” groups were housed either in a tank with large platforms over the water or in normal cages without paradoxical sleep deprivation.

MAIN OUTCOME MEASURES: Morris Water Maze was employed for task learning and spatial memory testing. Rats in all groups were placed at six random starting points each day for four consecutive days. Each placement was repeated for two trials; the first trial represented reference memory and the second working memory. Rats in the first trial were allowed to locate the submerged platform within 120 seconds. Data, including swimming distance, escape latency, swimming velocity, percentage of time in correct quarter, and memory scores were recorded and analyzed automatically by behavioral analyses systems for Morris Water Maze.

RESULTS: Twenty-eight rats were included in the final analysis, without any loss. In the first trial, between day 2 and 4, escape latency and swimming distance increased significantly in the paradoxical sleep deprivation group compared to the home cage control and tank control groups (P < 0.01); percentage of time in correct quarter and memory scores, however, decreased in the paradoxical sleep deprivation group compared to the home cage control and tank control groups (P < 0.01). The escape latency, swimming distance, percentage of time in correct quarter, and memory scores in the second trial was not significantly different among the three groups (P > 0.05).

CONCLUSION: Paradoxical sleep deprivation inhibits spatial reference memory, but not working memory.

Key Words: paradoxical sleep deprivation; Morris Water Maze; spatial reference memory; working memory

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