Cerebral Ischemia-Reperfusion Is Associated With Upregulation of Cofilin-1 in the Motor Cortex.

Cerebral ischemia is one of the leading causes of death. Reperfusion is a critical stage after thrombolysis or thrombectomy, accompanied by oxidative stress, excitotoxicity, neuroinflammation, and defects in synapse structure. The process is closely related to the dephosphorylation of actin-binding proteins (e.g., cofilin-1) by specific phosphatases. Although studies of the molecular mechanisms of the actin cytoskeleton have been ongoing for decades, limited studies have directly investigated reperfusion-induced reorganization of actin-binding protein, and little is known about the gene expression of actin-binding proteins. The exact mechanism is still uncertain. The motor cortex is very important to save nerve function; therefore, we chose the penumbra to study the relationship between cerebral ischemia-reperfusion and actin-binding protein. After transient middle cerebral artery occlusion (MCAO) and reperfusion, we confirmed reperfusion and motor function deficit by cerebral blood flow and gait analysis. PCR was used to screen the high expression mRNAs in penumbra of the motor cortex. The high expression of cofilin in this region was confirmed by immunohistochemistry (IHC) and Western blot (WB). The change in cofilin-1 expression appears at the same time as gait imbalance, especially maximum variation and left front swing. It is suggested that cofilin-1 may partially affect motor cortex function. This result provides a potential mechanism for understanding cerebral ischemia-reperfusion.

Electroacupuncture-Induced Neuroprotection against Cerebral Ischemia in Rats: Role of the Dopamine D2 Receptor.

Background. Cerebral ischemia is known to produce brain damage and related behavioural deficits, including memory deficits and motor disorders. Evidence shows that EA significantly promotes recovery of neurological function and thus improves quality of life. Objective. Evidence exists for the involvement of catecholamines in human neuroplasticity. A better understanding of dopaminergic (DAergic) modulation in this process will be important. Methods. A total of 72 adult male Sprague-Dawley (SD) rats were divided into 6 groups: normal, model, EA, spiperone group, EA + spiperone group, and pergolide. The middle cerebral artery occlusion (MCAO) model was used in all 6 groups except the normal group. A behavioural assessment was conducted at 1, 3, 5, and 7 days after MCAO. The percent of brain infarct area was also determined 7 days after MCAO. Tyrosine hydroxylase (TH) and growth-associated protein 43 (GAP-43) fluorescence double labeling was performed in the striatum. Results. In this study, we found that EA at Fengchi (GB20) acupoints resulted in marked improvements based on a behavioural assessment. Both TTC staining and GAP-43 immunofluorescence labeling results showed that EA treatment reduced ischemia injury and promoted neuroplasticity compared with the model group. The D2R-selective agonist, pergolide, showed similar results, but these results were reversed by the D2R-selective antagonist, spiperone. We also found that there were more colocalization and expression of GAP-43 and TH in the EA and pergolide groups than those in the other groups. Conclusion. These results suggest that the neuroplasticity induced by EA was mediated by D2 autoreceptors in DAergic neurons.

Electroacupuncture inhibition of hyperalgesia in rats with adjuvant arthritis: involvement of cannabinoid receptor 1 and dopamine receptor subtypes in striatum.

Electroacupuncture (EA) has been regarded as an alternative treatment for inflammatory pain for several decades. However, the molecular mechanisms underlying the antinociceptive effect of EA have not been thoroughly clarified. Previous studies have shown that cannabinoid CB1 receptors are related to pain relief. Accumulating evidence has shown that the CB1 and dopamine systems sometimes interact and may operate synergistically in rat striatum. To our knowledge, dopamine D1/D2 receptors are involved in EA analgesia. In this study, we found that repeated EA at Zusanli (ST36) and Kunlun (BL60) acupoints resulted in marked improvements in thermal hyperalgesia. Both western blot assays and FQ-PCR analysis results showed that the levels of CB1 expression in the repeated-EA group were much higher than those in any other group (P = 0.001). The CB1-selective antagonist AM251 inhibited the effects of repeated EA by attenuating the increases in CB1 expression. The two kinds of dopamine receptors imparted different actions on the EA-induced CB1 upregulation in AA rat model. These results suggested that the strong activation of the CB1 receptor after repeated EA resulted in the concomitant phenomenon of the upregulation of D1 and D2 levels of gene expression.

[Effects of repeated electroacupuncture on gene expression of cannabinoid receptor-1 and dopamine 1 receptor in nucleus accumbens-caudate nucleus region in inflammatory-pain rats].

OBJECTIVE: To observe the effect of repeated electroacupuncture (EA) on the expression of cannabinoid receptor-1 (CB 1) mrRNA and dopamine 1 receptor (D 1) mRNA in Nucleus Accumbens (NAC)-Caudate Nucleus (CN) region in inflammatory-pain rats, so as to study its underlying mechanism in analgesia. METHODS: A total of 30 SD rats were randomized into normal control, model, EA, EA+ AM 251 and WIN 55212-2 groups, with 6 cases in each group. EA (2 Hz/100 Hz, 1 -3 mA) was applied to "Zusanli"(ST 36) and "Kunlun"(BL 60) for 30 min, once every other day, and 4 sessions all together. Arthritis model was established by injection of Freund's complete adjuvant 0.05 mL in the rat's left ankle. Thermal pain threshold (paw withdrawal latency, PWL) was detected before and after modeling and after repeated EA and/or intraperitoneal injection of AM 251(an inverse antagonist at the CB 1 cannabinoid receptor, 0. 1 mg/100 g) and WIN 55212-2 (a potent cannabinoid receptor agonist, 0. 2 mg/100 g). The expression of CB 1 receptor mRNA and D 1 receptor mRNA in the NAC-CN region was measured by real time fluorescence quantitative-polymerase chain reaction. RESULTS: Compared with the control group, the pain threshold values of the model group was decreased significantly (P<0.01). In comparison with the model group, the pain threshold values of the EA group and WIN 55212-2 group were increased considerably on day 10 (P<0. 01). No significant differences were found between the EA+ AM 251 and model groups and between the EA and WIN 55212-2 groups in PWL after the treatment (P>0.05). Compared with the control group, both CB 1 R mRNA and D 1 R mRNA expression levels in the model group were increased slightly, while in comparison with the model group and EA+ AM 251 group, CB 1 R mRNA and D 1 R mRNA expression levels in the EA group and WIN 55212-2 group were upregulated obviously. No significant differences were found between the EA + AM 251 and model groups and between the EA and WIN 55212-2 groups in CB 1 R mRNA and D 1 R mRNA expression levels.

[Dynamic changes of dopamine and its metabolite levels in the rat striatum after cerebral ischemia-reperfusion and electroacupuncture].

OBJECTIVE: To explore the involvement of dopamine (DA) and its metabolites in the extracellular fluid of the striatum on the resisting action of electroacupuncture (EA) for acute cerebral ischemia-reperfusion (CI/R) injury. METHODS: A total of 50 SD male rats were randomly divided into normal control, sham-operation (sham), sham + EA, CI/R model, CI/R + EA groups. CI/R model was induced by right middle cerebral artery occlusion (MCAO) for 90 min and reperfusion for 225 min. EA (2 Hz, 3 mA, continuous waves) was applied to "Fengchi" (GB 20) for 20 min, with a 10 min rest, and given once again fo 20 min. The concentrations of DA and its metabolites [3,4- dihydroxy-phenyl acetic acid (DOPAC) and homovanillic acid (HVA)] in the extracellular fluid of the striatum were determined by microdialysis and high performance liquid chromatography (HPLC). RESULTS: The extracellular levels of DA, DOPAC and HVA in normal group, sham group and sham+ EA group had no significant changes during the whole study. The extracellular level of DA peaked 15-45 min after CI and 0-30 min after CI/R (P < 0.05). A rising trend was also observed 120 min following CI/R. DOPAC level peaked 15 min and 75 min after CI and 75 min after CI/R. After EA, DA level was significantly lower in EA group than that in model group 90 min after CI/R (P < 0.05), and no peak was observed again. After EA, DOPAC level maintained its basic level, and no peak was found after CI/R. The changing trend of HVA was similar to that of DOPAC, and the extracellular HVA level in EA + model group was significantly lower than that in model group 75 min after CI/R. CONCLUSION: EA can decrease the accumulation of DA and its metabolites in the extracellular fluid of the striatum, which may contribute to its effect in preventing the brain from CI/R injury.

[Protective effect of low-level laser irradiation on acupuncture points combined with iontophoresis against focal cerebral ischemia-reperfusion injury in rats].

OBJECTIVE: To investigate the effects of low-level laser irradiation on acupuncture points combined with iontophoresis against brain damage after middle cerebral artery occlusion (MCAO) in rats. METHODS: Sixty-nine SD rats were randomly divided into five groups, including normal group, sham operation group, model group, electro-acupuncture group and low-level laser irradiation on acupuncture points combined with iontophoresis group (LLLI group). The cerebral ischemia-reperfusion (I/R) model was established by thread embolism of middle cerebral artery. The rats in the LLLI group, as well as the electro-acupuncture group were given treatment as soon as the occlusion finished (0 hour) and 12, 24 hours after the occlusion. We observed the changes of neurological deficit scores and the body weight of the rats at different time. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the ratos brain tissue were tested. RESULTS: The neurological deficit score of the LLLI group was significantly lower than that of the model group. The body weight and the activity of SOD of the rats decreased slightly, and the content of MDA decreased significantly after the treatment. CONCLUSION: The low-level laser irradiation on acupuncture points combined with iontophoresis can prevent focal cerebral ischemia-reperfusion injury. One of its mechanisms may be increasing the activity of SOD and decreasing the damage of the oxidation products to the body.