TPPU Downregulates Oxidative Stress Damage and Induces BDNF Expression in PC-12 Cells.

Objective: Ischemia-reperfusion is an ongoing clinical challenge that can lead to a series of pathological changes including oxidative stress. The inhibition of soluble epoxide hydrolase inhibitor (sEH) by 1-(1-propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl]urea (TPPU) results in an anti-inflammatory, cardioprotective, and blood vessel growth-promoting effects. Therefore, this study focused on the protective effect of TPPU on a rat pheochromocytoma (PC-12) cell oxidative stress model induced by H2O2. Methods: CCK-8 and Hoechst 33342 were used to evaluate cell apoptosis and western blot to detect the apoptotic proteins and brain-derived neurotrophic factor (BDNF) expression. Result: The incubation with 100 µM, 50 µM, and 25 µM TPPU significantly increased PC-12 cell viability. Epoxyeicosatrienoic acid (EET) pretreatment also protected PC-12 cells from oxidative stress. In addition, TPPU reduced caspase-3 and Bax expression and induced Bcl-2 expression, and EETs exerted the same effect on caspase-3 expression as TPPU. A positive relationship was found between TPPU or EET incubation and BDNF expression. Conclusion: These results revealed that TPPU reduced PC-12 cell oxidative stress injury induced by H2O2 and promoted BDNF expression.

Processing of Paired Click-Tone Stimulation in the Mice Inferior Colliculus.

The inferior colliculus (IC) is known as a neuronal structure involved in the integration of acoustic information in the ascending auditory pathway. However, the processing of paired acoustic stimuli containing different sound types, especially when they are applied closely, in the IC remains poorly studied. We here firstly investigated the IC neuronal response to the paired stimuli comprising click and pure tone with different inter-stimulus (click-tone) intervals using in vivo loose-patch recordings in anesthetized BALB/c mice. It was found that the total acoustic evoked spike counts decreased under certain click-tone interval conditions on some neurons with or without click-induced supra-threshold responses. Application of click could enhance the minimum threshold of the neurons responding to the tone in a pair without changing other characteristics of the neuronal tone receptive fields. We further studied the paired acoustic stimuli evoked excitatory/inhibitory inputs, IC neurons received, by holding the membrane potential at -70/0 mV using in vivo whole-cell voltage-clamp techniques. The curvature and peak amplitude of the excitatory/inhibitory post-synaptic current (EPSC/IPSC) could be almost unchanged under different inter-stimulus interval conditions. Instead of showing the summation of synaptic inputs, most recorded neurons only had the EPSC/IPSC with the amplitude similar as the bigger one evoked by click or tone in a pair when the inter-stimulus interval was small. We speculated that the IC could inherit the paired click-tone information which had been integrated before reaching it.

Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.