Effect of electroacupuncture of different acupoint groups on cerebral cortical neurovascular unit and PI3K/Akt signaling in rats with ischemic stroke

Abstract

To observe the protective effect of electroacupuncture (EA) on neurovascular unit, neurological function in rats with cerebral ischemia (CI), so as to explore its mechanisms underlying improvement of ischemic cerebral tissue. Male SD rats, SPF grade, were randomly and equally divided into sham operation group, model group, EA group Ⅰ and EA group Ⅱ，27 rats in each group. The CI model was established by occlusion of the middle cerebral artery (MCAO). EA (2 Hz/20 Hz, 0.5 mA) was applied to "Quchi"(LI11), "Hegu"(LI4), "Zusanli"(ST36) and "Shuigou"(GV26) for rats of the EA group Ⅰ, and to "Baihui"(GV26), "Fengfu"(GV16), "Neiguan"(PC26) and "Xinshu"(BL15) for rats of the EA group Ⅱ for 20 min, once a day for 14 days. The modified neurologic severity score (mNSS) was calculated according to the state of locomotor, sensory, and reflex parameters. Transmission electron microscope (TEM) was used to observe the neuronal structure of the ischemic cerebral area. The CD34 positive cells (for microvessels) of the ischemic brain tissue were detected by using immunohistochemistry, and the expression levels of cerebral phosphatidylinositol-3 kinase (PI3K) and protein kinase B (Akt) mRNAs were detected by quantitative real-time-PCR, respectively. Along with the extension of time, the mNSS at 4 h, and 3, 7 and 14 d after CI were apparently decreased, and the number of CD34 positive cells from 3 d to 14 d after CI, and the expression of PI3K mRNA and Akt mRNA from 3 d to 7 d were significantly increased in the model，EAⅠand EA Ⅱ group （P<0.01, P<0.05）. Compared with the sham operation group, the mNSS at 4 h, and 3, 7 and 14 d, and CD34-positive number and PI3K mRNA and Akt mRNA expression levels at 3, 7 and 14 d were significantly increased in the model group (P<0.01, P>0.05). In comparison with the model group, the mNSS at 3, 7 and 14 d were obviously decreased (P<0.01), and the CD34-positive number and PI3K and Akt mRNA expression levels at 3, 7 and 14 d considerably increased in both EA group Ⅰ and Ⅱ (P<0.01, P<0.05). The therapeutic effect of EA group Ⅱ was significantly superior to that of EA group Ⅰ in lowering mNSS at 14 d, up-regulating the CD34-positive number at 7 and 14 d,and PI3K mRNA at 3, 7 and 14 d and Akt mRNA at 3 and 7 d (P<0.05, P<0.01). Results of TEM showed an irregular shape of neurons with nuclear pyknosis, non-uniform chromatin, more organelle loss, swollen mitochondrial Golgi complex and expansion of rough endoplasmic reticulum, being relatively milder in the EA group Ⅰ, particularly in the EA group Ⅱ. EA therapy can improve the neurological function in cerebral ischemia rats, which may be related to its effects in protecting the neurovascular unit and up-regulating PI3K/Akt signal pathway. The effects of EA at GV26, GV16, PC26 and BL15 are better than those of EA at LI11, LI4, ST36 and GV26.