Manual acupuncture relieves microglia-mediated neuroinflammation in a rat model of traumatic brain injury by inhibiting the RhoA/ROCK2 pathway.

OBJECTIVE: To investigate the regulatory mechanism of manual acupuncture (MA) on microglial polarization-mediated neuroinflammation after traumatic brain injury (TBI), focusing on the RhoA/Rho-associated coiled coil-forming protein kinase (ROCK2) pathway. METHODS: Sprague Dawley (SD) rats were used to generate a TBI model using Feeney's freefall epidural impact method. MA was performed on half of the TBI model rats, while the others remained untreated. Acupuncture was administered at GV15, GV16, GV20, GV26, and LI4. At the end of the intervention, rat brain tissue samples were collected, and the microglial M1 polarization status was observed by immunofluorescence labeling of CD86, an M1 microglia-specific protein. RhoA/ROCK2 signaling components were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. An enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of inflammatory factors. RESULTS: Compared with normal rats, the CD86 expression density in the untreated TBI model rats was high and showed an aggregated expression pattern. The genes and proteins of the RhoA/ROCK2 signaling pathway were highly expressed, and inflammatory factors were significantly increased. The CD86 expression density in TBI rats after MA was reduced compared to that in untreated TBI rats and showed a scattered distribution. The expression of RhoA/ROCK2 signaling pathway genes and proteins was also significantly reduced, and inflammatory factors were decreased. CONCLUSION: These results show that MA may inhibit M1 polarization of microglia by regulating the RhoA/ROCK2 signaling pathway, thereby reducing neuroinflammation in TBI.

Dietary Zinc Modulates Matrix Metalloproteinases in Traumatic Brain Injury.

Animal models of mild traumatic brain injury (mTBI) provide opportunity to examine the extent to which dietary interventions can be used to improve recovery after injury. Animal studies also suggest that matrix metalloproteinases (MMPs) play a role in tissue remodeling post-TBI. Because dietary zinc (Zn) improved recovery in nonblast mTBI models, and the MMPs are Zn-requiring enzymes, we evaluated the effects of low- (LoZn) and adequate-Zn (AdZn) diets on MMP expression and behavioral responses, subsequent to exposure to a single blast. MMP messenger RNA expression in soleus muscle and frontal cortex tissues were quantified at 48 h and 14 days post-blast. In muscle, blast resulted in significant upregulation of membrane-type (MT)-MMP, MMP-2, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 at 48 h post-injury in rats consuming AdZn. At 14 days post-blast, there were no blast or dietary effects observed on MMP levels in muscle, supporting the existence of a Zn-responsive, functional repair and remodeling mechanism. In contrast, blast resulted in a significant downregulation of MT-MMP, TIMP-1, and TIMP-2 and a significant upregulation of MMP-3 levels at 48 h post-injury in cortex tissue, whereas at 14 days post-blast, MT-MMP, MMP-2, and TIMP-2 were all downregulated in response to blast, independent of diet, and TIMP-1 were significantly increased in rats fed AdZn diets despite the absence of elevated MMPs. Because the blast injuries occurred while animals were under general anesthesia, the increased immobility observed post-injury in rats consuming LoZn diets suggest that blast mTBI can, in the absence of any psychological stressor, induce post-traumatic stress disorder-related traits that are chronic, but responsive to diet. Taken together, our results support a relationship between marginally Zn-deficient status and a compromised regenerative response post-injury in muscle, likely through the MMP pathway. However, in neuronal tissue, changes in MMP/TIMP levels after blast indicate a variable response to marginally Zn-deficient diets that may help explain compromised repair mechanism(s) previously associated with the systemic hypozincemia that develops in patients with TBI.

Neuroprotective effect of breviscapine on traumatic brain injury in rats associated with the inhibition of GSK3ß signaling pathway.

Breviscapine, a standardized Chinese herbal medicine extracted from Erigeron breviscapine, has been widely used to treat cerebrovascular diseases. However, there are no reports about the neuroprotective effects and underlying molecular mechanisms of breviscapine on traumatic brain injury (TBI). Therefore, this study was aimed to investigate the effects of breviscapine on rats with TBI insult and illuminate the underlying mechanism. We created a traumatic brain-injured model with breviscapine lateral ventricle injection and evaluated the expressional changes of glycogen synthase kinase 3 beta (GSK3ß) as well as the GSK3ß-involved signaling pathways including apoptosis and axonal growth. At 7, 14, 21days after injection, we found a great reduction of motor disability in TBI rats following breviscapine treatment, which was accompanied with a notably increased expression of phospho-Ser9-GSK3ß (p-Ser9-GSK3ß) and decreased expression of phosphor-Try216-GSK3ß (p-Try216-GSK3ß) at 7days after injection. Concomitantly, an enhanced expression of synaptic marker synaptophysin (SYP) together with a weakened expression of pro-apoptotic caspase3 was observed after TBI rats were treated with breviscapine. Terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling (TUNEL) immunohistochemical assay and SYP immunofluorescence staining also confirmed the result. This study suggests that breviscapine inhibits the GSK3ß signaling pathway to promote neurobehavioral function following neurotrauma. These events may provide a new insight into the mechanism of breviscapine treating brain injury.

Resveratrol Treatment Prevents Hippocampal Neurodegeneration in a Rodent Model of Traumatic Brain Injury.

AIM: Traumatic brain injury (TBI) is a complex process. Increasing evidence has demonstrated that reactive oxygen species contribute to brain injury. Resveratrol (RVT) which exhibits significant antioxidant properties, is neuroprotective against excitotoxicity, ischemia, and hypoxia. The aim of this study was to evaluate the neuroprotective effects of RVT on the hippocampus of a rat model of TBI. MATERIAL AND METHODS: Twenty eight rats were divided into four groups. A moderate degree of head trauma was induced using Feeney"s falling weight technique. Group 1 (control) underwent no intervention or treatment. Head trauma was induced in Group 2 (trauma) and no drug was administered. Head trauma was induced in Group 3 and low-dose RVT (50 mg/kg per day) was injected. In Group 4, high-dose RVT (100 mg/kg per day) was used after head trauma. Brain tissues were extracted immediately after perfusion without damaging the tissues. Histopathological and biochemistry parameters were studied. RESULTS: Brain tissue malondialdehyde (MDA) levels in the trauma group were significantly higher than those in the control, lowdose RVT-treated, and high-dose-RVT-treated groups. The superoxide dismutase (SOD) levels in the control group were significantly higher than those in the trauma, low-dose RVT-treated, and high-dose RVT-treated groups. Glutathione peroxidase (GSH-Px) levels in the control group were significantly higher than those in the trauma and low-dose RVT-treated groups. The level of oxidative deoxyribonucleic acid (DNA) damage (8-OHdG/106 dG) in the trauma group was higher than that in the control group, low-dose RVT-treated, and high-dose RVT-treated groups. CONCLUSION: Resveratrol has a healing effect on neurons after TBI.