Lavender essential oil (LO) is a traditional medicine used for the treatment of Alzheimer's disease (AD). It was extracted from Lavandula angustifolia Mill. This study was designed to investigate the effects of lavender essential oil (LO) and its active component, linalool (LI), against cognitive impairment induced by D-galactose (D-gal) and AlCl3 in mice and to explore the related mechanisms. Our results revealed that LO (100 mg/kg) or LI (100 mg/kg) significantly protected the cognitive impairments as assessed by the Morris water maze test and step-though test. The mechanisms study demonstrated that LO and LI significantly protected the decreased activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), and protected the increased activity of acetylcholinesterase (AChE) and content of malondialdehyde (MDA). Besides, they protected the suppressed nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression significantly. Moreover, the decreased expression of synapse plasticity-related proteins, calcium-calmodulin-dependent protein kinase II (CaMKII), p-CaMKII, brain-derived neurotrophic factor (BDNF), and TrkB in the hippocampus were increased with drug treatment. In conclusion, LO and its active component LI have protected the oxidative stress, activity of cholinergic function and expression of proteins of Nrf2/HO-1 pathway, and synaptic plasticity. It suggest that LO, especially LI, could be a potential agent for improving cognitive impairment in AD.

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Many publications have reported the growing application of complementary and alternative medicine, particularly the use of Chinese herbal medicine (CHM) in combination with routine pharmacotherapy (RP) for senile vascular dementia (SVD), but its efficacy remains largely unexplored. The purpose of this study is to evaluate the efficacy of CHM adjunctive therapy (CHMAT), which is CHM combined with RP, in the treatment of SVD. Publications in seven electronic databases were searched extensively, and 27 trials with a total of 1961 patients were included for analysis. Compared with RP alone, CHMAT significantly increased the effective rate [odds ratio (OR) 2.98, 95% confidence interval (CI) 2.30, 3.86]. In addition, CHMAT showed benefits in detailed subgroups of the Mini-Mental State Exam (MMSE) score from time of onset to 4 weeks (WMD 3.01, 95% CI 2.15, 3.87), 8 weeks (weighted mean difference (WMD) 2.30, 95% CI 1.28, 3.32), 12 weeks (WMD 2.93, 95% CI 2.17, 3.69), and 24 weeks (WMD 3.25, 95% CI 2.61, 3.88), and in the activity of daily living scale score from time of onset to 4 weeks (WMD -4.64, 95% CI -6.12, -3.17), 8 weeks (WMD -4.30, 95% CI -6.04, -2.56), 12 weeks (WMD -3.89, 95% CI -4.68, -3.09), and 24 weeks (WMD -4.04, 95% CI -6.51, -1.57). Moreover, CHMAT had positive effects on changes in the Hasegawa dementia scale, National Institutes of Health Stroke Scale, Clinical Dementia Rating, and Montreal Cognitive Assessment scores, as well as blood fat levels (total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and apolipoprotein E), platelet aggregation rate (1-min platelet aggregation rate, 5-min platelet aggregation rate, and maximal platelet aggregation rate), and blood rheology (whole-blood viscosity and hematocrit). No serious or frequently occurring adverse effects were reported. Weaknesses of methodological quality in most trials were assessed using the Cochrane risk of bias tool, while the quality level of Grades of Recommendations Assessment Development and Evaluation (GRADE) evidence classification indicated 'very low'. This systematic review suggests that CHM as an adjunctive therapy can improve cognitive impairment and enhance immediate response and quality of life in SVD patients. However, because of limitations of methodological quality in the included studies, further research of rigorous design is needed.

Ginsenoside Rg1 is one of the major active ingredients of Panax ginseng and has showed notable improving learning and memory effects in several behavioral tasks, such as water maze, shuttle-box, and step-through, based on avoidance. However, there was no report about the role of Rg1 on the performance of reward-directed instrumental conditioning, which could reflect the adaptive capacity to ever-changing environments. Thus, in this study, the reward devaluation test and conditional visual discrimination task were conducted to study the ameliorating effects of Rg1 on cognitive deficits, especially the loss of adaptation capacity in chronic restraint stress (CRS) rat model. Our results showed that rat subjected to CRS became insensitive to the changes in outcome value, and it significantly harmed the rat's performance in conditional visual discrimination task. Moreover, the levels of BDNF, TrkB, and Erk phosphorylation were decreased in the prefrontal cortex of CRS rats. However, these changes were effectively reversed by Rg1 (5 and 10 mg/kg, i.p.). Therefore, it demonstrated that Rg1 has a good ability to improve learning and memory and also ameliorate impaired adaptive capacity induced by CRS. This amelioration effect of Rg1 might be mediated partially by BDNF/TrkB/Erk pathway in prefrontal cortex. Copyright © 2016 John Wiley & Sons, Ltd.

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Abstract:Objectives: The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polygalasaponin (HPS) on senescence accelerate mouse P8 (SAMP8) mice, an effective Alzheimer's disease (AD) model, and to research the relevant mechanisms. Methods: The cognitive-enhancing effects of HPS on SAMP8 mice were assessed using Morris water maze (MWM) and step-through passive avoidance tests. Then N-methyl-D-aspartate (NMDA) receptor subunit expression for both the cortex and hippocampus of mice was observed using Western blotting. Results: HPS (25 and 50 mg/kg) improved the escape rate and decreased the escape latency and time spent in the target quadrant for the SAMP8 mice in the MWM after oral administration of HPS for 10 d. Moreover, it decreased error times in the passive avoidance tests. Western blotting showed that HPS was able to reverse the levels of NMDAR1 and NMDAR2B expression in the cortex or hippocampus of model mice. Conclusions: The present study suggested that HPS can improve cognitive deficits in SAMP8 mice, and this mechanism might be associated with NMDA receptor (NMDAR)-related pathways.