ABSTRACT
Objective To investigate the effect of rapid eye movement (REM) sleep deprivation on spatial memory and hippocampal cellular prion protein (PrPC) expression and to explore the underlying mechanism of cognitive impairment induced by sleep deprivation.Methods Adult Sprague-Dawley rats were sorted by weight,randomly divided into three groups:the cage control (CC) group,the tank control (TC) group,and the sleep deprivation (SD) group.Rats were deprived of REM sleep for 72 h using the modified multiple platform method.The Morris water maze task was used to assess hippocampal-dependent spatial memory.After sleep deprivation,the rats were sacrificed and their brain tissue was analyzed for PrPC protein expression via Western blotting.Hippocampal neuron axon elongation was examined as well after lentivector-mediated RNA interference (RNAi) of PrPC in primary cultured rat hippocampal neurons.Results REM sleep deprivation for 72 h resulted in spatial memory impairment.The number of times of rats passing through the platform was decreased significantly in the SD group (3.17 ±0.95) compared with the CC (7.17 ±0.95) and TC (6.50 ±0.62) groups (Z =2.026 6,Z =2.026 6,P ＜0.05),the mean value of proximity to the platform (mm) was greater for rats of the SD group (711.74 ± 33.99) compared to those of theCC (592.32±31.31) andTC (580.86±11.36) groups (Z=-2.001 6,Z=-2.4820,P ＜ 0.05).REM sleep deprivation for 72 h resulted in reduced PrPC level in the hippocampus (0.33 ± 0.10) compared with the CC (1.01 ±0.33) and TC (0.96 ±0.27) groups (Z=2.152 9,Z=2.152 9,P ＜ 0.05).In primary cultured hippocampal neurons,axon elongation(μm) was inhibited 7 days in infected neurons (326.28 ± 12.53) compared with normal (555.00 ±30.43) or negative control (558.70 ±23.10) cells (Z =4.768 4,Z =4.877 0,P ＜ 0.05).Conclusion These findings suggest that PrPC-mediated hippocampal neuron axon elongation inhibition is probably involved in spatial memory impairment induced by sleep deprivation in rats.
ABSTRACT
Objective To investigate the cytotoxic effects of differentiated PC12 cells afterinfected by prion protein 106-126 peptide.Methods The PC12 cells were infected by prion protein 106-126peptide after differentiated by nerve growthfactor(NGF).Cell viability andthe morphological changes were observed.The energy metabolize and apoptosis was detected.Results Afterinfected by this peptide,cell viability decreasedfrom(98.1±1.9)% to (69.2±4.7)%,and apoptosis peak Was observed byflow cytometry.Aboutthe process of the cytotoxic effects,afterthe cells affected by PrP106-126,oxidative stress presented and existed continually,and then the intracellular free calcium concentrate increased from (185.74±12.93)nmol/L to (493.00±58.71)nmol/L subsequently,the activity of Ca2+ ATPase decreased from 54.92±4.05 to 34.92±4.86,the mitochondrial membrane potential decreasedto 65%,and also the energy metabolize disorder,the cells presented apoptosisinthe end.The changed Bcl-2/Bax system involvedinthe apoptosis.Conclusions Prion protein106-126 peptide caninduce apoptosisin differentiated PC12 cells and presented cellulartoxicity definitely.It might be a perfect model to study the cellular toxicity of prion protein.Continual oxidative stress could causetheintracellularfree calcium concentrate and disturb the energy metabolize,and the apoptosis might be the end-result.The oxidative stress of might play a startup and important role.