The triglyceride glucose index is associated with the cerebral small vessel disease in a memory clinic population.

BACKGROUND AND OBJECTIVES: Insulin resistance (IR) has been associated with the cerebral small vessel disease (cSVD). However, as the surrogate marker of IR, there is little known about the relationship between the triglyceride glucose (TyG) index and cSVD. In this cross-sectional study, we aimed to evaluate the relationship between the TyG index and cSVD in a memory clinic population and explore the value of TyG index to improve the risk stratification of cSVD. METHODS: We included participants who attended our memory clinic from January 2016 to December 2020. TyG index was determined as ln [fasting triglyceride (mg/dL) × fasting plasma glucose (mg/dL)/2]. We assessed lacunes, microbleeds, white matter hyperintensity (WMH) and enlarged perivascular spaces (EPVS) on MRI and calculated the total cSVD burden. RESULTS: A total of 297 subjects were included (median age: 65 years, male sex: 64.98%). In the adjusted model, when dividing TyG index into quartiles, subjects with TyG index in the top quartile, compared with those in the bottom quartile, were more likely to have lacunes (P = 0.035), moderate-severe WMH (P = 0.001), a higher grade of deep WMH (P = 0.004), a higher grade of PVWMH (P = 0.032), a higher grade of EPVS (P = 0.002), and a higher cSVD score (P < 0.001). When introducing TyG index into traditional risk factors to predict moderate to severe cSVD, both area under the curve (0.745 vs 0.802, P = 0.003) and integrated discrimination index (0.080, 95% CI 0.050-0.110, P < 0.001) displayed an improvement from TyG index. CONCLUSIONS: The TyG index is correlated with cSVD and may have the potential to be a surrogate marker of insulin resistance and optimize the risk stratification.

Formononetin attenuates Aß25-35-induced adhesion molecules in HBMECs via Nrf2 activation.

Brain vascular inflammation plays a crucial role in the pathogenesis of Alzheimer's disease (AD). As a central pathogenic factor in AD, the extracellular buildup of amyloid-ß (Aß) induces brain microvascular endothelial cells activation, impairs endothelial structure and function. Formononetin (FMN) has been reported to protect against Alzheimer's disease (AD) and attenuates vascular inflammation in atherosclerosis. However, its involvement in regulating vascular inflammation of AD has not been investigated. In the study, we found that FMN significantly attenuates Aß25-35-induced expression of adhesion molecules, including intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the human brain microvascular endothelial cells (HBMECs), suggesting that FMN inhibits Aß25-35-induced brain endothelial cells inflammatory response. Moreover, we observed that FMN attenuates Aß25-35-induced translocation of NFκB (p65) into the nucleus of HBMECs, and found that FMN treatment induces Nrf2 expression and attenuates Nrf2-Keap1 association in a dose-dependent manner in HBMECs. Furthermore, we demonstrated that Nrf2 silencing significantly attenuates FMN-reduced NFκB (p65) activation and nuclear translocation. Lastly, our results showed that FMN treatment attenuates Aß25-35-induced adhesion of THP-1 cell to endothelial cell monolayer. Collectively, these findings suggest that FMN attenuates Aß25-35-induced activation in human brain microvascular endothelial cells, which at least in part was mediated through Nrf2 pathways.

Shikonin Attenuates Chronic Cerebral Hypoperfusion-Induced Cognitive Impairment by Inhibiting Apoptosis via PTEN/Akt/CREB/BDNF Signaling.

Shikonin (SK) exerts neuroprotective effects; however, to date, its protective effect against chronic cerebral hypoperfusion- (CCH-) induced vascular dementia (VaD) has not been investigated. Therefore, the current study investigated whether SK could mitigate the cognitive deficits caused by CCH. The effects of SK treatment on the PTEN/Akt/CREB/BDNF signaling pathway and apoptosis in hippocampal neurons were examined in a rat model of VaD established via bilateral common carotid artery occlusion (BCCAO). Fifty-two rats were randomly divided into 4 groups: sham, vehicle, SK-L (10 mg/kg SK per day), and SK-H (25 mg/kg SK per day). SK was regularly administered by gavage for 2 weeks. The results of the water maze test revealed that the escape latency in the vehicle group was significantly longer than that in the sham group, and rats in the vehicle group spent a smaller proportion of time in the target quadrant than those in the sham group. SK treatment reduced the escape latencies and increased the proportion of time spent in the target quadrant. Nissl staining showed morphological damage in the CA1 areas of the hippocampus in the vehicle group. SK treatment alleviated the injuries to hippocampal neurons. Western blot analysis showed higher p-PTEN and lower p-Akt, p-CREB, and BDNF expression in the vehicle group than in the sham group. SK administration reversed the upregulation of p-PTEN and the downregulation of p-Akt, p-CREB, and BDNF. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling- (TUNEL-) positive cells in the hippocampal CA1 region of the vehicle group was significantly increased. Treatment with SK decreased the number of positive cells. Furthermore, as marker proteins of apoptosis, bcl-2 expression was decreased and bax expression was increased; thus, the ratio of bcl-2/bax was decreased in the vehicle group. SK treatment upregulated the expression of bcl-2 and downregulated the expression of bax, thereby elevating the bcl-2/bax ratio. Moreover, the aforementioned effects of SK were dose-dependent. The effect of 25 mg/kg per day was more obvious than that of 10 mg/kg per day. In conclusion, SK inhibited hippocampal neuronal apoptosis to protect against CCH-induced injury by regulating the PTEN/Akt/CREB/BDNF signaling pathway, consequently improving cognitive impairment.

Lithium chloride ameliorated spatial cognitive impairment through activating mTOR phosphorylation and inhibiting excessive autophagy in the repeated cerebral ischemia-reperfusion mouse model.

Lithium has been previously demonstrated to alleviate cognitive impairment caused by neurodegenerative diseases and acute brain injuries; however, the specific mechanism remains elusive. In the present study, the C57BL/6 mouse model of spatial cognitive impairment induced by repeated cerebral ischemia-reperfusion was established. Morris water maze test was performed to evaluate the levels of spatial cognitive impairment. Nissl staining was used to observe any morphological alterations, whilst western blotting was performed to measure the expression levels of microtubule-associated protein light chain 3 (LC3) and Beclin1 in addition to mTOR phosphorylation. LiCl was found to significantly improve spatial learning and memory impairments according to data from the Morris water maze test. Nissl staining indicated that LiCl inhibited neuronal damage in the CA1 region of the hippocampus. Additionally, LiCl increased mTOR phosphorylation, reduced beclin1 expression and reduced the LC3 II/I expression ratio. Taken together, these findings suggest that LiCl may alleviate the spatial cognitive impairment induced by repeated cerebral ischemia-reperfusion. This observation may be attributed to the inhibition of excessive autophagy by LiCl through mTOR signaling activation.

Iron dysregulation in vascular dementia: Focused on the AMPK/autophagy pathway.

Recent researches suggested that iron dysregulation play an important role in the pathogenesis of vascular dementia (VD). Iron deposition had been found in hippocampus in vascular dementia model in recent research. Nevertheless, the underlying mechanisms of iron deposition and its neurotoxicity in vascular dementia was still unclear. Thus, our research was aimed at whether the neurotoxicity of iron was associated with autophagy regulation. We established a chronic cerebral hypoperfusion model in the rat brain in order to mimic the vascular dementia using permanent bilateral common carotid artery occlusion (2VO). The preparation of iron overloaded rats model by intraperitoneal injection of iron dextran. Following, we tested the learning and memory function of each group using Morris Water Maze. Consequently, we analyzed the iron content and iron transport related molecules (TFR1, DMT1) in hippocampus. Furthermore, we examined the effect of iron deposition on autophagy-related molecules including AMPK, Beclin1 and LC3 and the number of autophagosomes in hippocampus. Last, we tested the apoptosis of neurons in hippocampus. We found that iron deposition in hippocampus in model groups which accompanied the decline of learning and memory function. And the expression of TFR1 and DMT1 were up-regulated in model groups. Moreover, iron deposition up-regulated the expression of AMPK, Beclin1 and LC3 and increase the number of autophagosomes in hippocampus. And the expression of Bax was up-regulated and Bcl-2 was down-regulated in iron deposition groups. To sum up, our data suggested that iron deposition increased AMPK/autophagy pathway associated molecules in the hippocampus and promoted neuronal apoptosis, which might be a new pathogenesis in vascular dementia.

FoxO1-mediated autophagy plays an important role in the neuroprotective effects of hydrogen in a rat model of vascular dementia.

Vascular dementia (VD) is a heterogeneous group of brain disorders in which cognitive impairment is attributed to cerebrovascular pathologies. Autophagy, a self-cannibalization mechanism, has been demonstrated to be involved in VD progression. Molecular hydrogen is known for its powerful anti-oxidative, anti-apoptotic, and anti-inflammatory activities, and it is also involved in autophagy. However, the effects of hydrogen on VD remain unclear. The current study found that hydrogen-rich water (HRW) significantly alleviated spatial learning and memory impairments. Similar to donepezil treatment, HRW also inhibited neuron loss and shrinkage in the hippocampal CA1 region. In addition, we found that HRW significantly increased the Bcl-2/Bax expression ratio and decreased cleaved caspase-3 expression levels in the hippocampus of VD rats. Moreover, electron microscopy revealed that HRW decreased the number of autophagosomes. We also observed that HRW reduced the increased ratio of LC3-II/I and Beclin 1 expression and saliently upregulated p62 expression. Furthermore, FoxO1 (a major mediator of autophagy regulation) and Atg7 levels were apparently decreased in the hippocampus of HRW-treated bilateral common carotid artery occlusion (2VO) rats. Taken together, these data show that molecular hydrogen exerts beneficial effects on cognitive impairment induced by chronic cerebral hypoperfusion. FoxO1-mediated autophagy plays an important role in the neuroprotective effects of hydrogen in a rat model of VD. Furthermore, the present findings highlight that HRW should be further investigated as a new therapeutic strategy for VD treatment in the future.

DL-3-n-butylphthalide alleviates vascular cognitive impairment induced by chronic cerebral hypoperfusion by activating the Akt/Nrf2 signaling pathway in the hippocampus of rats.

Oxidative stress induced by chronic cerebral hypoperfusion (CCH) plays an important role in the pathogenesis of vascular cognitive impairment (VCI). The Akt/Nrf2 signaling pathway is one of the most important antioxidative stress pathways. To explore whether NBP (DL-3-n-butylphthalide) could alleviate VCI induced by CCH via activating the Akt/Nrf2 signaling pathway and modifying the levels of apoptosis-related proteins, adult male Sprague-Dawley rats were subjected to permanent occlusion of bilateral common carotid arteries (BCCAO) and treated either with vehicle or NBP (applied in two doses, 40 mg/kg and 80 mg/kg) while sham operated animals were treated with vehicle. Treatments were administered daily for 28 days. The obtained results indicate that both administrated doses of NBP significantly ameliorated the spatial learning and memory impairments as indicated by the Morris water maze test while Hematoxylin-Eosin staining revealed that morphological defects in the CA1 area of hippocampus were improved. Moreover, NBP reversed the BCCAO-induced downregulation of investigated oxidative stress-related proteins (p-Akt, t-Nrf2, n-Nrf2 and HO-1) along with the upregulation of pro-apoptotic molecule, Bax and reduction of the expression of anti-apoptotic protein, Bcl-2. According to presented results, NBP may have a protective effect against cognitive and morphological impairments induced by CCH via activation of Akt/Nrf2 signaling pathway and inhibition of apoptotic cascade.

Cerebrolysin alleviates cognitive deficits induced by chronic cerebral hypoperfusion by increasing the levels of plasticity-related proteins and decreasing the levels of apoptosis-related proteins in the rat hippocampus.

The incidence of vascular dementia (VaD) has rapidly increased over the past few decades. Although officially approved medications for VaD remain limited, cerebrolysin (CBL) had preventive and treatment effects on VaD in some clinical trials. However, the underlying mechanisms have not been determined. The aim of this study was to determine whether CBL protects against cognitive deficits in a rat model of VaD induced by chronic cerebral hypoperfusion by increasing the levels of plasticity-related proteins and decreasing the levels of apoptosis-related proteins. In our study, adult male Sprague-Dawley rats were subjected to bilateral common carotid artery occlusion (BCCAO) surgery. The animals were randomly divided into four groups after the operation: Sham, Vehicle, L-CBL (2.5ml/kg), and H-CBL (5ml/kg). CBL was administered after the operation daily for 28 days. The CBL treatment significantly decreased the escape latency and increased the percentage of time the rat spent in the target quadrant of the Morris water maze (MWM) task. Pathological changes in the hippocampus, such as reduced cell count numbers and obvious pyknosis, were observed using haematoxylin-eosin (HE) staining. Furthermore, CBL significantly increased the expression of plasticity-related synaptic proteins, such as postsynaptic density protein 95 (PSD-95), protein kinase C subunit gamma (PKCγ), phosphorylated cAMP response element binding protein (p-CREB), and decreased the expression of apoptosis-related proteins in the hippocampus. In summary, CBL likely protects against cognitive deficits by improving synaptic plasticity and decreasing apoptosis.

Lipoxin A4 methyl ester alleviates vascular cognition impairment by regulating the expression of proteins related to autophagy and ER stress in the rat hippocampus.

Since autophagy and endoplasmic reticulum stress mechanisms are involved in some neurodegenerative and cerebral vascular diseases, we suspected that similar mechanisms might participate in vascular cognitive impairments induced by chronic cerebral hypoperfusion. Lipoxin A4 methyl ester (LXA4 ME) is an inflammation inhibitor that exhibits potent protective effects in experimental stroke models. In an earlier study, we found that LXA4 ME improved cognitive deficit in a rat model of vascular cognitive impairment created using bilateral common carotid artery ligation (BCCAL) and two-vessel occlusion (2VO). In this study, LXA4 ME treatment of 2VO rats improved brain morphological defects. We found that LXA4 ME reduced the expression of some autophagy- and ERS-related factors in the hippocampus of 2VO rats, namely C/EBP homologous protein, beclin1 and the ratio of microtubule-associated protein light chain 3 II (LC3-II) to LC3-I. By contrast, LXA4 ME upregulated the protein expression of phospho-mTOR, total-mTOR, glucose-regulated protein 78 and spliced and unspliced X-box binding protein-1 mRNA. Differential protein regulation by LXA4 ME might underlie its ability to protect cognition after chronic cerebral hypoperfusion.

Lithium chloride administration prevents spatial learning and memory impairment in repeated cerebral ischemia-reperfusion mice by depressing apoptosis and increasing BDNF expression in hippocampus.

Lithium has been reported to have neuroprotective effects, but the preventive and treated role on cognition impairment and the underlying mechanisms have not been determined. In the present study, C57Bl/6 mice were subjected to repeated bilateral common carotid artery occlusion to induce the learning and memory deficits. 2 mmol/kg or 5 mmol/kg of lithium chloride (LiCl) was injected intraperitoneally per day before (for 7 days) or post (for 28 days) the operation. This repeated cerebral ischemia-reperfusion (IR) induced dynamic overexpression of ratio of Bcl-2/Bax and BDNF in hippocampus of mice. LiCl pretreatment and treatment significantly decreased the escape latency and increased the percentage of time that the mice spent in the target quadrant in Morris water maze. 2 mmol/kg LiCl evidently reversed the morphologic changes, up-regulated the survival neuron count and increased the BDNF gene and protein expression. 5 mmol/kg pre-LiCl significantly increased IR-stimulated reduce of Bcl-2/Bax and p-CREB/CREB. These results described suggest that pre-Li and Li treatment may induce a pronounced prevention on cognitive impairment. These effects may relay on the inhibition of apoptosis and increasing BDNF and p-CREB expression.

Lipoxin A4 methyl ester ameliorates cognitive deficits induced by chronic cerebral hypoperfusion through activating ERK/Nrf2 signaling pathway in rats.

Lipoxin A4 (LXA4) is known for its powerful anti-inflammatory function. Current studies in vitro suggest that LXA4 possesses novel antioxidant effect. The aim of this study is to examine whether Lipoxin A4 methyl ester (LXA4 ME) has neuroprotective effects against chronic cerebral hypoperfusion, and if so, whether the effects of LXA4 ME are associated with its potential antioxidant property. Adult male Sprague-Dawley rats were subjected to permanent bilateral common carotid artery occlusion (BCCAO) and randomly assigned into four groups: sham (sham-operated) group, vehicle (BCCAO+normal saline) group, LXA4 ME10 (BCCAO+LXA4 ME 10 ng per day) group and LXA4 ME100 (BCCAO+LXA4 ME 100 ng per day) group. LXA4 ME was administered through intracerebroventricular injection for 2 consecutive weeks. LXA4 ME significantly alleviated spatial learning and memory impairments, as assessed by Morris water maze and inhibited the loss of neurons in the CA1 region of the hippocampus. Biochemically, LXA4 ME phosphorylated extracellular signal regulated kinase (ERK) 1/2 and enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) expression and its nuclear translocation, as well as NAD(P)H: quinone oxidoreductase 1 (NQO1) expression. LXA4 ME reduced lipid peroxidative production in the hippocampus, as measured by immunohistochemical staining for 4-Hydroxynonenal (4-HNE). In addition, LXA4 ME significantly elevated the ratio of Bcl-2/Bax and decreased cleaved caspase-3 expression in the hippocampus. Therefore, these data suggest that LXA4 ME exerts beneficial effects on the cognitive impairment induced by chronic cerebral hypoperfusion through attenuating oxidative injury and reducing neuronal apoptosis in the hippocampus, which is most likely associated with the activation of ERK/Nrf2 signaling pathway.