Effect of "Tiaoshen Tongluo" acupuncture on nerve function injury, muscle tension and neurotransmitters through Nrf2/ROS pathway in spastic rats after stroke

Abstract

To observe the effect of "Tiaoshen Tongluo" acupuncture (TTA) at "Dingzhongxian" (MS5) and right "Dingpangxian" (MS8) on neurological injury, muscle tension and neurotransmitters through nuclear transcription factor E2 related factor 2 (Nrf2)/reactive oxygen species (ROS) signaling pathway in spastic rats after stroke, so as to explore its mechanisms underlying relief of post-stroke spasm (PSS). A total of 90 male SD rats were randomly divided into 6 groups, i.e. sham operation, PSS model, medication, non-acupoint acupuncture, TTA, TTA+ML385 groups, with 15 rats in each group. The PSS model was established by middle cerebral artery occlusion. After modeling, rats of the medication group were treated by gavage of baclofen (0.4 mg/kg), once daily for 7 days. For rats of the non-acupoint acupuncture group, the spot about 10 mm above the iliac crest and below the armpit of the affected side was needled, and for those of the TTA group and TTA+ML385 group, EA stimulation (1 mA, 2 Hz/15 Hz) was applied to MS5 and right MS8 for 10 min, once daily for 7 consecutive days. Intraperitoneal injection of ML385 ［ a specific nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor, 30 mg/kg］ was given to rats of the TTA+ML385 group before TTA was performed. The rats' neurological deficit score (0-4 points) was evaluated by referring to Zea Longa's methods and the muscular spasm degree of the quadriceps femoris of the left hindlimb (0-4 points) assessed by using Ashworth scale (MAS). The muscular tension of the left quadriceps femoris was measured by using a tension sensor, and Hoffman (H)-reflex response and M and H waves of electromyogram of the muscle between the metatarsals of the left foot were measured using an electrophysiological recorder. The cerebral infarction volume was measured after 2,3,5-triphenyltetrazolium chloride (TTC) staining. The contents of γ-aminobutyric acid (GABA), glycine (Gly), glutamic acid (Glu) and aspartic acid (Asp) of the right cortical infarct area were detected by using high performance capillary electrophoresis, and the contents of 5-hydroxytryptamine (5-HT), dopamine (DA) and norepinephrine (NE) were detected by fluorescence spectrophoto-metry, as well as the level of ROS in the right cerebral cortical infarction tissues was detected by dihydroethidium staining. The expression levels of Nrf2 and heme oxygenase-1 (HO-1) proteins in the infarcted cerebral area were detected using Western blot. Compared with the sham operation group, the neurological deficit score, MAS score, percentage of cerebral infarction volume, Hmax/Mmax ratio, contents of Glu and Asp and ROS level were significantly increased (P<0.001), whereas the muscle tone, stimulation threshold for inducing H-reflex, GABA, Gly, 5-HT, DA and NE contents, cerebral Nrf2 and HO-1 protein expression levels were apparently decreased (P<0.001) in the model group. In comparison with the model group, the neurological deficit score, MAS score, percentage of cerebral infarction volume, Hmax/Mmax ratio, contents of Glu, Asp and ROS levels were decreased (P<0.001), and the muscle tone, stimulation threshold for inducing H-reflex, GABA, Gly, 5-HT, DA and NE contents, Nrf2 and HO-1 protein expressions were increased (P<0.001, P<0.01) in both the medication and TTA groups. No significant differences were found between the non-acupoint group and model group, and between the medication and TTA groups in all the indexes mentioned above (P>0.05). After administration of ML385, the effects of TTA in reducing neurological deficit score, MAS score, Hmax/Mmax, percentage of cerebral infarct volume, Glu, Asp, ROS, and up-regulating H-reflex threshold, GABA, Gly, 5-HT, DA, NE, Nrf2 and HO-1 levels were eliminated (P<0.001，P<0.05,P<0.01). TTA can improve neurological behavior and muscle spasm in rats with PSS, which may be associated with its functions in regulating the levels of neurotransmitters in the cortical infarcted area by activating the Nrf2/ROS signaling pathway.