Regulatory Effects of Clock and Bmal1 on Circadian Rhythmic TLR Expression.

Circadian locomotor output cycles kaput (Clock) and brain and muscle ARNT-like 1 (Bmal1) are two core circadian clock genes. They form a heterodimer that can bind to the E-box element in the promoters of Period circadian protein (Per) and Cryptochrome (Cry) genes, thereby inducing the rhythmic expression of circadian clock control genes. Toll-like receptors (TLRs) are type I transmembrane proteins belonging to the pattern recognition receptor (PRR) family. They can recognize a variety of pathogens and play an important role in innate immunity and adaptive immune responses. Recent studies have found that the circadian clock is closely associated with the immune system. TLRs have a certain correlation with the circadian rhythms; Bmal1 seems to be the central mediator connecting the circadian clock and the immune system. Research on Bmal1 and TLRs has made some progress, but the specific relationship between TLRs and Bmal1 remains unclear. Understanding the relationship between TLRs and Clock/Bmal1 genes is increasingly important for basic research and clinical treatment.

[Protective effect of edaravone on chlorpyrifos-induced brain injury in rats and its mechanism].

Objective: To investigate the protective effect of edaravone on chlorpyrifos-induced neuronal apoptosis and its mitochondrial mechanism. Methods: Under the principle of randomization and double-blindness, the rats were divided into control group, chlorpyrifos group, and edaravone group (n=6). The rats in edaravone group were treated with edaravone (10 mg/1.6 ml/kg, ip.) 1 h after chlorpyrifos injection. After continuous injection of chlorpyrifos and edaravone for 28 days, the learning and memory abilities of the rats were tested by open field and water maze tests. The rat brain tissue was collected after cardiac perfusion, and the neuronal damage in the hippocampus of the brain was detected by HE staining and the mitochondrial and nuclear damage were observed by transmission electron microscopy. The contents of Na+-K+-ATPase and ATP were measured to evaluate mitochondrial damage. The expression of mitochondrial fission protein DRP1 and phosphorylation at Ser 637 of DRP1 were determined by immunohistochemistry and immunoblotting. Results: Compared with the control group, the total movement distance and average speed of the rats in the chlorpyrifos group were decreased significantly within 3 minutes of the open field test (P＜0.01), and the escape latency within 1 minute of the water maze test was prolonged significantly. The number of platform crossings was reduced significantly (P＜0.01), the activity of ATPase in brain tissue was decreased significantly (P＜0.01) , the content of ATP and the phosphorylation level of Ser637 of mitochondrial DRP1 were decreased significantly (P＜0.05, P＜0.01). After edaravone treatment, the total movement distance and average speed of rats in the open field test were increased (P＜0.05), the latency in the water maze test was decreased, and the number of crossing platforms was increased (P＜0.01), brain pathological sections showed that nerve cells were arranged neatly, nucleus and mitochondrial damage was significantly improved, the activity of ATPase in brain tissue was increased (P＜0.01), the levels of ATP and mitochondrial DRP1 Ser637 phosphorylation increased (P＜0.05, P＜0.01).Conclusion: Edaravone alleviates chlorpyrifos-induced brain injury in rats by promoting the phosphorylation of DRP1 at Ser637.

Carvacryl acetate, a semisynthetic monoterpenic ester obtained from essential oils, provides neuroprotection against cerebral ischemia reperfusion-induced oxidative stress injury via the Nrf2 signalling pathway.

Carvacryl acetate (CA) is a semisynthetic monoterpenic ester obtained from essential oils, and it exerts an antioxidation effect. The purpose of our study was to investigate whether CA could provide neuroprotection against oxidative stress caused by cerebral ischemia-reperfusion injury (CIRI) and elucidate the underlying mechanism. Middle cerebral artery occlusion (MCAO)-induced damage was established in Sprague Dawley (SD) rats and PC12 cells were exposed to hydrogen peroxide (H2O2) to imitate oxidative stress damage. TTC, HE and Nissl staining were used to observe the pathological morphology of lesions. The contents of ROS and MDA, and the activity of SOD were measured to reflect the level of oxidative stress. In addition, the TUNEL method was used to assess injuries in vitro, and the expression of Nrf2 was determined by immunohistochemical staining and western blot analysis. Importantly, we constructed and validated Nrf2 knockdown PC12 cells to confirm the key role of Nrf2 in the neuroprotective effect of CA against oxidative stress injuries. CA alleviated CIRI in rats with MCAO, as shown by brain tissue pathophysiology. The contents of ROS and MDA were reduced, and the SOD activity was augmented by the simultaneous promotion of Nrf2 expression. In addition, the H2O2-induced injury in Nrf2-knockdown PC12 cells was more serious than it was in control cells, and CA-mediated neuroprotection was exclusively inhibited by the knock down of Nrf2 in PC12 cells. In conclusion, it is shown here that CA has the effect of relieving cerebral ischemia reperfusion-induced oxidative stress injury via the Nrf2 signalling pathway.