To investigate the role of clock gene Bmal1, Per2 and Egr1 expression in learning and memory undergoing sevoflurane anesthesia after acute sleep deprivation.

72 male SD rats were equally divided into four groups using a random number table (n=18) : normal control group (group Control), do not do any processing; sleep deprivation group (group SD), acute sleep deprivation for 96 h; sevoflurane group (group Sev), suffering 2.5% sevoflurane for 3 h; sleep deprivation+sevoflurane group (group SD+Sev), 96 h sleep deprivation followed by 3 h 2.5% sevoflurane inhalation. The Morris water maze, for spatial memory acquisition test, was used to measure the time percent of target quadrant and numbers of platform-site crossovers before sleep deprivation (T0) and at 1 d (T1), 3 d (T2), 7 d (T3) after inhalation anesthesia. Rats were sacrificed after spatial memory acquisition test. Brain hippocampus samples were obtained for determination of Bmal1, Per2 and Egr1 expression by Western blot, and neuron morphology was observed by the Nissl staining.

Compared with Control group, the percentage of time in target quadrant and the numbers of platform-site crossovers were significantly decreased at T1 and T2 in Sev group (P<0.05); and compared with Control group, the percentage of time in target quadrant and the numbers of platform-site crossovers were also significantly decreased at T1, T2 and T3 in SD group rats (P<0.05). Compared with Sev group rats (the percentages of time in target quadrant: T1: (32.37±1.36)%; T2: (30.91±1.26)%; T3: (33.78±2.20)%; the numbers of platform-site crossovers: T1: (4.55±0.39); T2: (3.11±0.37); T3: (3.95±0.34)), the percentages of time in target quadrant (T1: (27.20±1.42)%; T2: (28.19±1.04)%; T3: (30.06±1.22)%) and the numbers of platform-site crossovers (T1: (3.11±0.46); T2: (3.30±0.38); T3: ( 3.20±0.39)) in SD+Sev group rats were significantly decreased at T1, T2 and T3 (all P<0.05). Compared with control group, the levels of hippocampal proteins Bmal1, Per2 and Egr1 were significantly reduced at T1 in Sev group (P<0.05). Compared with control group, the level of hippocampal protein Per2 was significantly increased, but the levels of hippocampal proteins Bmal1 and Egr1 were significantly decreased at T1 and T2 in SD group (P<0.01). Compared with Sev group, the levels of hippocampal proteins Bmal1 and Egr1 were significantly reduced at T1, T2 and T3 in SD+Sev group (P<0.01), and the protein level of hippocampal Per2 was significantly decreased at T1, but then increased at T2 and T3 in SD+Sev group (P<0.01). The hippocampal Nissl staining in CA1 at T2 revealed that there were irregular distribution of pyramidal neurons existed in Sev group, and vacuolar degeneration with vague outlines of pyramidal neurons in SD group, while pyramidal neuron atrophy and few number of Nissl bodies, compared with control group, were observed in SD+Sev group.

Acute sleep deprivation following with sevoflurane anesthesia resulted in hippocampal memory impairment, which was associated with abnormal expression of hippocampal Bmal1, Per2 and Egr1.

Sleep deprivation; Inhalation anesthesia; Sevoflurane; Learning and memory; Clock gene