ABSTRACT
OBJECTIVE@#To explore the effect of electrical stimulation at auricular points (EAS) combined with sound masking on the expression of cAMP-response element binding protein (CREB), brain-derived neurotrophic factor (BDNF) and tyrosine receptor kinase B (TrkB) in the auditory cortex of tinnitus rats.@*METHODS@#A total of 27 adult male SD rats were randomly divided into a control group, a model group and an EAS group. The rats in the model group and the EAS group were intervened with intraperitoneal injection of sodium salicylate to induce tinnitus model, while the rats in the control group were intervened with injection of 0.9% NaCl solution. After the model was successfully established, the rats in the EAS group were treated with electrical stimulation at "Shenmen" (TF) and "Yidan" (CO), combined with sound masking; the treatment was given once a day for 15 days. The gap prepulse inhibition of acoustic startle (GPIAS) and prepulse inhibition (PPI) testing were performed using the acoustic startle reflex starter package for rats. The expression of BDNF, TrkB, CREB and p-CREB in the auditory cortex of each group were measured with Western Blot analysis.@*RESULTS@#① Compared with the control group, the GPIAS values in 12 kHz, 16 kHz, 20 kHz and 28 kHz were significantly decreased in the model group (all 0.05).@*CONCLUSION@#EAS could improve the GPIAS values of high-frequency background sound in tinnitus rats, which may be related with the upregulation of the BDNF/TrkB/CREB signaling pathway in the auditory cortex, leading to the reversion of the maladaptive plasticity.
Subject(s)
Animals , Male , Rats , Acupuncture Points , Auditory Cortex , Brain-Derived Neurotrophic Factor , Metabolism , Cyclic AMP Response Element-Binding Protein , Metabolism , Electric Stimulation , Rats, Sprague-Dawley , Receptor, trkB , Metabolism , Tinnitus , Metabolism , TherapeuticsABSTRACT
Excessive autophagy is one of the crucial factors of cerebral ischemia-reperfusion injury (CIRI), which has been demonstrated to be one of the targets for acupuncture treatment of ischemic stroke. In the present paper, we make a review about the development of acupuncture intervention induced improvement of CIRI (such as reducing the infarction area, improving learning-memory ability and motor function) by regulating autophagy in animal studies. Outcomes showed that acupuncture intervention can function in 1) inhibiting CIRI-induced increase of the number of lysosomes and autophagic lysosomes, and relieving structural injury of mitochondria, and reducing the number of autophagosome in the central region of the ischemic cerebral cortex tissue; 2) down-regulating the expression of microtubule-associated protein Ⅱ light chain 3 (LC3Ⅱ) and the ratio of LC3-Ⅱ/LC3-Ⅰ in the ischemic cerebral region, and 3) regulating the expression of Beclin 1 (autophagy-related gene), promoting the expression of P62 (autophagy-related adaptor protein). In addition, acupuncture can also regulate phosphoinositide 3 kinase (PI3K)- protein kinase B (AKT)- mammalian target of rapamycin complex 1(mTOR) signaling at different time-points (down-regulation at the early stage and up-regulation at the later stage), and activating AMP-activated protein kinase (AMPK)-mTOR- UNC51-like kinase-1 signaling to relieve cerebral ischemic injury. These results reveal some mechanisms of acupuncture therapy underlying improvement of CIRI and provide experimental basis for clinical application of acupuncture therapy in the treatment of ischemic stroke.
ABSTRACT
Objective: To investigate the effect of puerarin on the regulation of AMPK-mTOR signaling pathway to inhibit autophagy and alleviate focal cerebral ischemia reperfusion injury. Methods: Forty male Sprague-Dawley rats were randomly divided into four groups: Sham group, model group, puerarin low-dose (50 mg/kg) group and puerarin high-dose (100 mg/kg) group. Pretreatment with puerarin for 7 d, then the middle cerebral artery occlusion (MCAO) model was established 0.5 h after the last administration according to Longa’s method. After 1.5 h of ischemia and 24 h of reperfusion, the neurological deficit scores were assessed, the infarct volume was calculated by TTC staining. The formation of autophagosome was observed by electron microscopy. The expression levels of LC3, p62, AMPK, p-AMPK, mTOR, p-mTOR, Ulk1, and pS757-Ulk1 were detected by Western blotting. Results: Compared with the Sham group, the neurological deficit scores and infarct volume in model group were significantly increased, the numbers of autophagosome increased, and the rate of LC3-II/LC3-I significantly increased, the expression level of p62 gradually decreased. The expression of p-AMPK was markedly up-regulated, while the expression of p-mTOR and pS757-Ulk1 was significantly down-regulated. Compared with the model group, the neurological deficit scores and infarct volume were significantly reduced, the number of autophagosome and the rate of LC3-II/LC3-I decreased, the expression of p62 was significantly up-regulated, the expression of p-AMPK was markedly down-regulated, the levels of p-mTOR and pS757-Ulk1 were significantly up-regulated. Conclusion: Puerarin alleviates cerebral ischemia-reperfusion injury may through suppressing autophagy via the AMPK-mTOR-Ulk1 signaling pathway.