Background/Aims: MicroRNA-9 (miR-9) plays important roles in nervous system diseases such as glioblastoma and neurodegenerative disorders. However, how miR-9 contributes to dementia requires further study. In this study, we evaluated the role of miR-9 in dementia and the molecular mechanisms underlying its effects. Methods: A rat model of dementia was created by occlusion of the bilateral common carotid artery (2VO) for 8 weeks. Learning and memory were assessed using the Morris Water Maze (MWM). MicroRNA expression profiling was performed according to a protocol provided by LC Sciences, and quantitative real-time PCR (qRT-PCR) was used to detect the level of miR-9. Transmission electron microscopy (TEM) and hematoxylin-eosin (HE) staining were used to assess pathological changes in brain tissue. Western blot and immunofluorescence were employed to detect the expression of β-site APP cleaving enzyme 1 (BACE1) and c-AMP response element-binding protein (CREB). Results: Learning and memory were significantly impaired in 2VO rats, and these changes were accompanied by neuronal loss and glial activation in brain tissues. miR-9 was greatly upregulated in both the hippocampus and cortex of rats following 2VO. Knockdown of endogenous miR-9 via lentiviral vector-mediated delivery of its antisense molecule (lenti-pre-AMO-miR-9) reduced the vulnerability to dementia, reversed the increase in BACE1 expression, and ameliorated the reduction in CREB expression triggered by 2VO. BACE1 protein levels were significantly increased, but CREB protein levels were significantly decreased in the presence of miR-9 in cultured neonatal rat neurons (NRNs). AMO-miR-9 rescued the upregulation of BACE1 and downregulation of CREB elicited by miR-9 in rats. Dual luciferase assay experiments showed that overexpression of miR-9 inhibited the expression of CREB by targeting its 3’UTR domain. CREB protein was downregulated by miR-9 overexpression which was reversed by miR-9 inhibition in cultured NRNs. TEM imaging showed that miR-9 caused damage to NRNs, which was reversed by addition of AMO-miR-9. Conclusion: We conclude that miR-9 plays an important role in regulating the process of dementia induced by 2VO in rats by increasing BACE1 expression via downregulation of CREB.

BackgroundA role for the NLRP3 inflammasome has been reported in various diseases, such as diabetes mellitus, atherosclerosis (AS), nephropathy, rheumatism, and others, although limited information is available concerning the role of the NLRP3 inflammasome, interleukin-1β (IL-1β) and interleukin-18 (IL-18) in patients with type 2 diabetes mellitus (T2DM) and carotid atherosclerosis (CAS). Therefore, this cross-sectional study investigated these inflammatory components in patients with T2DM complicated with carotid atherosclerosis (T2DM + CAS).MethodsA total of 107 inpatients or outpatients were included,including 81 T2DM + CAS patients and 26 T2DM patients. Patients with T2DM or T2DM + CAS were recruited to compare the expression levels of NLRP3 pathway genes (NLRP3, ASC and caspase-1 mRNA) and the serum IL-1β and IL-18 concentrations. In the T2DM + CAS group, patients with thickened intima media thickness (IMT) and those with plaques were compared, and the correlation of the 5 variables with Crouse scores were analyzed.ResultsThe expression of NLRP3 pathway genes except caspase-1 was significantly higher in patients with T2DM and CAS compared to T2DM patients. Serum IL-1β and IL-18 concentrations shows no difference between the T2DM + CAS and T2DM group. In the T2DM + CAS group, the expression levels of the three inflammasome genes and IL-18 were increased in patients with thickened IMT compared to those with the plaque. All of the above factors negatively correlated with Crouse scores.ConclusionNLRP3 inflammasome pathway activity is significantly increased in patients with AS and T2DM at the early stage of plaque formation.

BackgroundDiabetes accelerates memory dysfunction in a continuous, slowly pathological process. Studies suggest that the time course of certain biomarkers can characterize the pathological course of the disease to provide information for early intervention. Thus, there is an urgent need for validated biomarkers to characterize the cognitive impairment induced by DM. We aimed to detect changes in cerebrospinal fluid biomarkers such as amyloid β42, phosphorylated tau protein, interleukin 6, and acetylcholine in diabetic rats over time, and to analyse the relationship between diabetes and cognitive impairment.MethodsRats were injected once intraperitoneally with 1% of streptozotocin to establish a diabetic model. Index changes were investigated longitudinally and all were measured at the end of the experiment at day 75. Aβ42, P-tau, IL-6, and ACh levels in CSF, insulin levels in plasma, and Aβ42 levels in plasma and brain tissue were measured by ELISA.ResultsCompared with control, the diabetic model showed ACh in CSF to be decreased by day 15, continuing lower out to day 75. Aβ42 changes in brain and blood showed the same trends but exhibited minima at different time points: day 30 in CSF and day 15 in plasma. After the minimum, Aβ42 in cerebrospinal fluid rose and levelled off lower than in the control group, whereas Aβ42 in plasma rose and went above the controls at day 30, slowly trending upwards for the remainder of the experiment. P-tau protein in CSF in diabetic rats showed an increasing trend, becoming significantly different from the controls at day 60 and day 75. Aβ42 in CSF was strongly negatively correlated with blood glucose at day 15 and was negatively correlated with insulin in serum, particularly at day 45.ConclusionOur longitudinal research model suggest that changes in the measured biomarkers appear before learning and memory impairments do. Aβ42 and ACh in the diabetes model group clearly changed from day 0 to day 45, and then P-tau and IL-6 varied significantly from day 45 to day 75. The reduced ACh levels observed possibly correlated with the factors common to changes in Aβ42, P-tau, and IL-6.

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