Nrf1 Reduces COX-2 Expression and Maintains Cellular Homeostasis After Cerebral Ischemia/Reperfusion By Targeting IL-6/TNF-α Protein Production.

Neuroinflammation has been considered involved in the process of cerebral ischemia-reperfusion injury (CIRI). Transcription factors play a crucial role in regulating gene transcription and the expressions of specific proteins during the progression of various neurological diseases. Evidence showed that transcription factor nuclear factor erythroid 2-related factor 1 (NFE2L1, also known as Nrf1) possessed strong biological activities including antioxidant, anti-inflammatory and neuroprotective properties. However, its role and potential molecular mechanisms in CIRI remain unclear. In our study, we observed a significant elevation of Nrf1 in the cerebral cortex following cerebral ischemia-reperfusion in rats. The Nrf1 downregulation markedly raised COX-2, TNF-α, IL-1ß, and IL-6 protein levels during middle cerebral artery occlusion/reperfusion in rats, which led to worsened neurological deficits, higher cerebral infarct volume, and intensified cortical histopathological damage. In subsequent in vitro studies, the expression of Nrf1 protein increased following oxygen-glucose deprivation/reperfusion treatment on neurons. Subsequently, Nrf1 knockdown resulted in a significant upregulation of inflammatory factors, leading to a substantial increase in the cell death rate. Through analyzing the alterations in the expression of inflammatory factors under diverse interventions, it is indicated that Nrf1 possesses the capacity to discern variations in inflammatory factors via specific structural domains. Our findings demonstrate the translocation of the Nrf1 protein from the cytoplasm to the nucleus, thereby modulating the protein expression of IL-6/TNF-α and subsequently reducing the expression of multiple inflammatory factors. This study signifies, for the first time, that during cerebral ischemia-reperfusion, Nrf1 translocases to the nucleus to regulate the protein expression of IL-6/TNF-α, consequently suppressing COX-2 expression and governing cellular inflammation, ultimately upholding cellular homeostasis.

12/15-Lipoxygenase Regulation of Diabetic Cognitive Dysfunction Is Determined by Interfering with Inflammation and Cell Apoptosis.

This study aimed to discuss the role of 12/15-lipoxygenase (12/15-LOX) regulation involved in diabetes cognitive dysfunction. First, Mini Mental State Examination (MMSE) test was used to evaluate cognitive ability in diabetic patients and normal controls. The plasma test showed that the plasma level of 12/15-LOX in patients with MMSE scores below 27 was significantly increased compared with that of the normal group. Second, 12/15-LOX inhibitor was administered to diabetic rats. Behavioral tests, biochemistry, enzyme-linked immunosorbent assays, and Western blotting were used in this study. We found that the levels of fasting and random blood glucose increased rapidly in diabetic rats, the levels of triglycerides and total cholesterol in the diabetic group increased, and insulin levels decreased significantly. In the Morris water maze test, the escape latency was prolonged, and the crossing times decreased in the diabetic group. Under the microscope, the apoptosis of hippocampal neurons in diabetic rats increased significantly. The levels of TNF-α, IL-6 and 12-hydroxyindoleic acid (12(S)-HETE) significantly increased, and the protein expression of 12/15-LOX, p38 MAPK, Aß1-42, caspase-3, caspase-9 and cPLA2 increased, while that of Bcl-2 decreased. However, the use of 12/15-LOX inhibitor reversed these results. Third, 12/15-LOX shRNA and p38MAPK inhibitor were administered to HT22 cells in high-glucose medium. The results of the cell experiment were consistent with those of the animal experiment. Our results indicated that the 12/15-LOX pathway participates in diabetic brain damage by activating p38MAPK to promote inflammation and neuronal apoptosis, and intervention 12/15-LOX can improve diabetic cognitive dysfunction.

N-linoleyltyrosine exerts neuroprotective effects in APP/PS1 transgenic mice via cannabinoid receptor-mediated autophagy.

Anandamide (AEA) analogs show fair effects in counteracting the deterioration of Alzheimer's disease (AD). Our previous studies demonstrated that AEA analog-N-linoleyltyrosine (NITyr) exerted significant activities. In our current research, the role and mechanisms of NITyr were assessed in APP/PS1 mice mimicking the AD model. NITyr improved motor coordination in the rotarod test (RRT) and ameliorated spatial memory in the Morris water maze (MWM) but did not increase spontaneous locomotor activity in the open field test (OFT). In addition, NITyr protected neurons against ß-amyloid (Aß) injury via hematoxylin-eosin (HE) and Nissl staining. Moreover, the related biochemical indexes showed that NITyr reduced the levels of Aß40 and Aß42 in the hippocampus but did not affect the expression of p-APP and ß-secretase 1 (BACE1). Furthermore, the autophagy inhibitor 3-methyladenine (3 MA) attenuated the effect of NITyr on animal behaviors and neurons. Meanwhile, NITyr upregulated the expression levels of LC3-II and Beclin-1, which were weakened by AM630 (an antagonist of CB2 receptor and a weak partial agonist of CB1 receptors). AM630 also weakened the role of NITyr in animal behaviors. Thus, NITyr improved behavioral impairment and neural loss by inducing autophagy mainly mediated by the CB2 receptor, and weakly mediated by the CB1 receptor.

N-Linoleyltyrosine Protects against Transient Cerebral Ischemia in Gerbil via CB2 Receptor Involvement in PI3K/Akt Signaling Pathway.

Anandamide (AEA) played potent neuroprotective activities via cannabinoid type 1 (CB1) and 2 (CB2) receptor. N-Linoleyltyrosine (NITyr), as an AEA analogue, was synthesized in our laboratory and evaluated the neuroprotective effects and mechanisms for the first time. NITyr was synthesized via substitution reaction. The neuroprotective effects of NITyr were evaluated in a gerbil model of transient cerebral ischemia. Each gerbil was subjected to open field test (OFT), Rotard rod test (RRT), Morris water maze (MWM) successively and executed after animal behaviors. Part of the brain was stained with hematoxylin and eosin (HE) and Nissl staining, and the rest for biochemical analysis. NITyr could not increase spontaneous locomotor activity and ameliorate the anxiety behavior in the OFT but could improve the motor coordination in the RRT and the spatial memory impairment in the MWM. Immunohistochemically, NITyr could attenuate the ischemia-induced neural loss in the hippocampus. The Enzyme-linked immunosorbent assay (ELISA) suggested that NITyr ameliorated the inflammation and oxidative stress. Consistently, NITyr could up-regulate the expressions of p-phosphadylinositol 3-kinase (PI3K) and p-Akt but not PI3K and Akt in the hippocampus. In addition to oxidative stress, CB2 receptor antagonist AM630 but not CB1 receptor antagonist AM251 could reverse the above phenomena. However, CB1 receptor antagonist AM251 could reverse oxidative stress. Accordingly, NITyr could up-regulate the expressions of CB2 but not CB1. NITyr could improve the motor coordination, learning and memory impairments, neural loss in the hippocampus and the inflammation of the mice via CB2 receptor involvement of PI3K/Akt signaling pathway.