Circadian Regulation by REV-ERBα Mediates Hippocampal E-LTP in a Time-dependent Manner

Circadian rhythms are driven by circadian oscillators, and these rhythms result in the biological phenomenon of 24-h oscillations. Previous studies suggest that learning and memory are affected by circadian rhythms. One of the genes responsible for generating the circadian rhythm is Rev-erbα. The REV-ERBα protein is a nuclear receptor that acts as a transcriptional repressor, and is a core component of the circadian clock. However, the role of REV-ERBα in neurophysiological processes in the hippocampus has not been characterized yet. In this study, we examined the time-dependent role of REV-ERBα in hippocampal synaptic plasticity using Rev-erbα KO mice. The KO mice lacking REV-ERBα displayed abnormal NMDAR-dependent synaptic potentiation (E-LTP) at CT12~CT14 (subjective night) when compared to their wild-type littermates. However, Rev-erbα KO mice exhibited normal E-LTP at CT0~CT2 (subjective day). We also found that the Rev-erbα KO mice had intact late LTP (L-LTP) at both subjective day and night. Taken together, these results provide evidence that REV-ERBα is critical for hippocampal E-LTP during the dark period.

Effect of Colored Noise on Circadian Oscillation and Internal Signal Stochastic Resonance in Biological Clock System / 生物化学与生物物理进展

The effect of colored noise on circadian oscillation and internal signal stochastic resonance(ISSR) has been studied in a Neurospora circadian clock system. The result shows that the correlation time of colored noise can affect strongly the strength of ISSR. For the case of no external signal(ES), the correlation time of colored noise plays a suppressive role for ISSR, and the suppressive role is increased with the increment of correlation time of colored noise. When the ES is injected to the system, with the increasing of the correlation time of colored noise, not only its suppressive role for ISSR is increased, but also the single peak ISSR can be transformed as internal single stochastic bi-resonance (ISSBR). There exists an optimal frequency of ES for the ISSR information amplification, while the ISSR is suppressed for another frequency of ES. In contrast to external colored noise, internal colored noise is more efficient to sustain and amplify the ISSR information. Furthermore, there exists a critical noise intensity for destroying the difference between white and colored noises.