Shikonin ameliorates oxidative stress and neuroinflammation via the Akt/ERK/JNK/NF-κB signalling pathways in a model of Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Shikonin plays protective roles in age-associated diseases. Therefore, we investigate the biological functions of shikonin and its mechanisms involved in PD pathogenesis. The neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to mimic PD-like conditions in animal models. The learning and memory capacities were assessed by Morris water-maze test, pole test, locomotor activity test and rotarod test. Neuroinflammation was determined by measuring the levels of tumour necrosis factor α (TNF-α), interleukin (IL)-1ß, IL-6, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). The quantification of superoxide dismutase, malondialdehyde and glutathione in substantia nigra was performed to estimate oxidative damage. Histopathologic changes were examined by haematoxylin and eosin staining. Immunofluorescence staining was conducted to determine the activation of astrocytes, tyrosine hydroxylase (TH)-positive neurons, and nuclear translocation of p65. Immunohistochemistry was performed to evaluate dopamine transporter (DAT)-positive neurons. Protein levels were measured by western blotting. Shikonin alleviates the cognitive and behavioural impairments. The death of dopaminergic neurons in nigra was attenuated by shikonin. The MPTP-induced neuroinflammation and oxidative stress in substantia nigra were alleviated by shikonin administration. Shikonin ameliorated the neuronal damage in nigra and inhibited the activation of astrocyte. Shikonin modulated the protein kinase B (Akt)/extracellular regulated kinase (ERK)/c-Jun N-terminal kinase (JNK)/nuclear factor κB (NF-κB) pathways. Shikonin ameliorates dopaminergic neuronal apoptosis by inhibiting oxidative stress and neuroinflammation via the Akt/ERK/JNK/NF-κB pathways in PD. The study has several limitations. First, in a previous study, levels of phosphorylated ERK were increased by MPTP. In our current study, we observed decreased p-ERK in nigra following MPTP treatment. Therefore, further investigation in the mechanisms of shikonin against PD progression is required. Second, the biological functions of shikonin need more exploration, including mitochondrial function and autophagy. Moreover, specific molecular targets for shikonin remain uncertain.

Ghrelin inhibits early brain injury due to subarachnoid hemorrhage via the Tim-3-mediated HMGB1/NF-κB pathway.

OBJECTIVE: To explore the protective effect of Ghrelin on EBI caused by SAH through the HMGB1/NF-κB pathway mediated by Tim-3. METHODS: Rats were divided into four groups (n = 6): Sham group (Sham), SAH+vehicle group (SAH), SAH + 0.02 µg/kg rhGhrelin group (rhGhrelin-L), SAH + 0.04 µg/kg rhGhrelin group (rhGhrelin-H). At 48 h after SAH, the behavioral impairment in rats was examined for using neurobehavioral scores. The pathological change in the temporal basal brain tissue was observed by HE, and the expression of GHSR-1α and Tim-3 in the temporal basal brain tissue was observed by Western blot. To further validate that rhGhrelin could inhibit SAH-induced EBI by the Tim-3-mediated HMGB1/NF-κB pathway, we treated rats with the AAV-Tim-3. The contents of the inflammatory factors IL-1ß, TNF-α, IL-6 was determined by ELISA, apoptosis was detected by TUNEL, the neurons were visualized by Nissl staining, the expression of GHSR-1α，Tim-3, HMGB1, RAGE, NF-κB p65 was determined by Western blot. RESULTS: Compared with the SAH group, rats treated with rhGhrelin had a significantly lower neurobehavioral score, significantly decreased inflammatory factors IL-1ß, TNF-α, IL-6 expression, significantly decreased apoptosis index, and significantly decreased Tim-3, HMGB1, RAGE, NF-κB p65 expression(p < 0.01). The protective effect of rhGhrelin on the SAH-induced EBI was reversed by the AAV-Tim-3. CONCLUSION: Ghrelin has beneficial effects against SAH-induced EBI by inhibiting the HMGB1/NF-κB pathway, which may be regulated by Tim-3.

Luteolin alleviates inflammation and autophagy of hippocampus induced by cerebral ischemia/reperfusion by activating PPAR gamma in rats.

BACKGROUND: Luteolin, a flavonoid compound with anti-inflammatory activity, has been reported to alleviate cerebral ischemia/reperfusion (I/R) injury. However, its potential mechanism remains unclear. METHODS: The binding activity of luteolin to peroxisome proliferator-activated receptor gamma (PPARγ) was calculated via molecular docking analysis. Rats were subjected to middle cerebral artery occlusion and reperfusion (MCAO/R). After reperfusion, vehicle, 25 mg/kg/d luteolin, 50 mg/kg/d luteolin, 10 mg/kg/d pioglitazone, 50 mg/kg/d luteolin combined with 10 mg/kg/d T0070907 (PPARγ inhibitor) were immediately orally treatment for 7 days. ELISA, TTC staining, H&E staining, immunohistochemistry, immunofluorescence and transmission electron microscope methods were performed to evaluate the inflammation and autophagy in damaged hippocampal region. The PPARγ, light chain 3 (LC3) B-II/LC3B-I and p-nuclear factor-κB (NF-κB) p65 proteins expression levels in damaged hippocampal region were analyzed. RESULTS: Luteolin showed good PPARγ activity according to docking score (score = - 8.2). Luteolin treatment downregulated the infarct area and the pro-inflammatory cytokines levels caused by MCAO/R injury. Moreover, luteolin administration ameliorated neuroinflammation and autophagy in damaged hippocampal region. Pioglitazone plays protective roles similar to luteolin. T0070907 concealed the neuroprotective roles of 50 mg/kg/d luteolin. CONCLUSIONS: Luteolin exerts neuroprotective roles against inflammation and autophagy of hippocampus induced by cerebral I/R by activating PPARγ in rats.

MFGE8 decreased neuronal apoptosis and neuroinflammation to ameliorate early brain injury induced by subarachnoid hemorrhage through the inhibition of HMGB1

AIM: Both MFGE8 and HMGB1 were vital players for aneurysmal subarachnoid hemorrhage. However, whether HMGB1 was served as the downstream target of MFGE8 was unknown. To test this new mechanism, we performed the SAH model in rats. METHOD: All treatments were injected intraventricularly into the right lateral ventricles. SAH grade, brain water content, and neurological function scores were evaluated. HMGB1 expression was studied by double immunofluorescence staining. HE and Nissl's staining were performed to observe the pathological change. Inflammatory factors were measured by ELISA method. RESULTS: High expression of MFGE8 could improve neurological function and reduce the brain edema and pro-inflammatory factors. Injection of rhMFGE8 inhibited HMGB1. To further verify the regulation of MFGE8 in HMGB1, we used rhHMGB1 and glycyrrhizin, and the results indicated MFGE8 produced excellent effect on SAH rats via inhibiting HMGB1. CONCLUSION: In a word, MFGE8 improved EBI caused by SAH, depending on HMGB1 that was the potential mechanism.

Dimethylfumarate alleviates early brain injury and secondary cognitive deficits after experimental subarachnoid hemorrhage via activation of Keap1-Nrf2-ARE system.

OBJECT: Oxidative stress and the inflammatory response are thought to promote brain damage in the setting of subarachnoid hemorrhage (SAH). Previous reports have shown that dimethylfumarate (DMF) can activate the Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2-antioxidant-responsive element (Keap1-Nrf2-ARE) system in vivo and in vitro, which leads to the downregulation of oxidative stress and inflammation. The aim of this study was to evaluate the potential neuroprotective effect of DMF on SAH-induced brain injury in rats. METHODS: Rats were subjected to SAH by the injection of 300 µl of autologous blood into the chiasmatic cistern. Rats in a DMF-treated group were given 15 mg/kg DMF twice daily by oral gavage for 2 days after the onset of SAH. Cortical apoptosis, neural necrosis, brain edema, blood-brain barrier impairment, learning deficits, and changes in the Keap1-Nrf2-ARE pathway were assessed. RESULTS: Administration of DMF significantly ameliorated the early brain injury and learning deficits induced by SAH in this animal model. Treatment with DMF markedly upregulated the expressions of agents related to Keap1-Nrf2-ARE signaling after SAH. The inflammatory response and oxidative stress were downregulated by DMF therapy. CONCLUSIONS: DMF administration resulted in abatement of the development of early brain injury and cognitive dysfunction in this prechiasmatic cistern SAH model. This result was probably mediated by the effect of DMF on the Keap1-Nrf2-ARE system.

Tert-butylhydroquinone alleviates early brain injury and cognitive dysfunction after experimental subarachnoid hemorrhage: role of Keap1/Nrf2/ARE pathway.

Tert-butylhydroquinone (tBHQ), an Nrf2 activator, has demonstrated neuroprotection against brain trauma and ischemic stroke in vivo. However, little work has been done with respect to its effect on early brain injury (EBI) after subarachnoid hemorrhage (SAH). At the same time, as an oral medication, it may have extensive clinical applications for the treatment of SAH-induced cognitive dysfunction. This study was undertaken to evaluate the influence of tBHQ on EBI, secondary deficits of learning and memory, and the Keap1/Nrf2/ARE pathway in a rat SAH model. SD rats were divided into four groups: (1) Control group (n=40); (2) SAH group (n=40); (3) SAH+vehicle group (n=40); and (4) SAH+tBHQ group (n=40). All SAH animals were subjected to injection of autologous blood into the prechiasmatic cistern once in 20 s. In SAH+tBHQ group, tBHQ was administered via oral gavage at a dose of 12.5 mg/kg at 2 h, 12 h, 24 h, and 36 h after SAH. In the first set of experiments, brain samples were extracted and evaluated 48 h after SAH. In the second set of experiments, changes in cognition and memory were investigated in a Morris water maze. Results shows that administration of tBHQ after SAH significantly ameliorated EBI-related problems, such as brain edema, blood-brain barrier (BBB) impairment, clinical behavior deficits, cortical apoptosis, and neurodegeneration. Learning deficits induced by SAH was markedly alleviated after tBHQ therapy. Treatment with tBHQ markedly up-regulated the expression of Keap1, Nrf2, HO-1, NQO1, and GSTα1 after SAH. In conclusion, the administration of tBHQ abated the development of EBI and cognitive dysfunction in this SAH model. Its action was probably mediated by activation of the Keap1/Nrf2/ARE pathway.