The effects of perindopril on cognitive impairment induced by d-galactose and aluminum trichloride via inhibition of acetylcholinesterase activity and oxidative stress

Exposure to Polystyrene Nanoplastics Led to Learning and Memory Deficits in Zebrafish by Inducing Oxidative Damage and Aggravating Brain Aging

Nanoplastics (NPs) may pass through the blood-brain barrier, giving rise to serious concerns about their potential toxicity to the brain. In this study, the effects of NPs exposure on learning and memory, the primary cognitive functions of the brain, are assessed in zebrafish with classic T-maze exploration tasks. Additionally, to reveal potential affecting mechanisms, the impacts of NPs exposure on brain aging, oxidative damage, energy provision, and the cell cycle are evaluated. The results demonstrate that NP-exposed zebrafish takes significantly longer for their first entry and spends markedly less time in the reward zone in the T-maze task, indicating the occurrence of learning and memory deficits. Moreover, higher levels of aging markers (β-galactosidase and lipofuscin) are detected in the brains of NP-exposed fish. Along with the accumulation of reactive free radicals, NP-exposed zebrafish suffer significant levels of brain oxidative damage. Furthermore, lower levels of Adenosine triphosphate (ATP) and cyclin-dependent kinase 2 and higher levels of p53 are observed in the brains of NP-exposed zebrafish, suggesting that NPs exposure also results in a shortage of energy supply and an arrestment of the cell cycle. These findings suggest that NPs exposure may pose a severe threat to brain health, which deserves closer attention.

Anti-Alzheimer's Activity of Polyphenolic Stilbene-Rich Acetone Fraction of the Oil-Removed Seeds of Passiflora edulis: in Vivo and in Silico Studies

The stilbene-rich acetone fraction in high yield (6.6 %, PEAS) of Passiflora edulis Sims was prepared and evaluated for neuroprotective activity in murine Alzheimer's disease model induced by aluminum chloride and D-galactose. The phytochemical and HPLC-DAD-MS analysis of the polyphenolic stilbene-rich acetone fraction showed that it contained different stilbenes including trans-piceatannol, scirpusins A-B and cassigarol E. The total phenolic content (TPC) of PEAS was 413.87±1.71 mg GAE eqv/g. The neuroprotective activity of PEAS is typically presented in the Morris water maze-reference Spatial Memory test, where the Alzheimer's mice treated at 100 mg/kg (Alz-ED1) and 200 mg/kg (Alz-ED2) spent less than 47 % and 66 % of the time, respectively, than the Alzheimer's model mice (Alz). Two simple stilbenes, trans-piceatannol and trans-resveratrol, showed selectively inhibitory activity in silico against acetylcholinesterase (AChE). Two stilbene dimers, cassigarol E and scirpusin A, exhibited low nanomolar inhibitory potential against AChE and butyrylcholinesterase (BChE), significantly lower than those of the positive control, donepezil and tacrine. These findings suggest that the stilbenes from P. edulis seeds, particularly the stilbene dimers, warrant further investigation as potential neuroprotective candidates in the prevention of cognitive deficits associated with Alzheimer's disease.

Sarcococca saligna ameliorated D-galactose induced neurodegeneration through repression of neurodegenerative and oxidative stress biomarkers

Sarcococca saligna is a valuable source of bioactive secondary metabolites exhibiting antioxidant, anti-inflammatory and acetylcholinesterase inhibitory activities. The study was intended to explore the therapeutic pursuits of S. saligna in amelioration of cognitive and motor dysfunctions induced by D-galactose and linked mechanistic pathways. Alzheimer's disease model was prepared by administration of D-galactose subcutaneous injection100 mg/kg and it was treated with rivastigmine (100 mg/kg, orally) and plant extract for 42 days. Cognitive and motor functions were evaluated by behavioral tasks and oxidative stress biomarkers. Level of acetylcholinesterase, reduced level of glutathione, protein and nitrite level, and brain neurotransmitters were analyzed in brain homogenate. The level of apoptosis regulator Bcl-2, Caspases 3 and heat shock protein HSP-70 in brain homogenates were analyzed by ELISA and colorimetric method, respectively. AChE, IL-1β, TNF-α, IL-1α and β secretase expressions were analyzed by RT-PCR. S. saligna dose dependently suppressed the neurodegenerative effects of D-galactose induced behavioral and biochemical impairments through modulation of antioxidant enzymes and acetylcholinesterase inhibition. S. saligna markedly (P < 0.05) ameliorated the level of brain neurotransmitters, Bcl-2, HSP-70 and Caspases-3 level. S. saligna at 500-1000 mg/kg considerably recovered the mRNA expression of neurodegenerative and neuro-inflammatory biomarkers, also evident from histopathological analysis. These findings suggest that S. saligna could be applicable in cure of Alzheimer's disease.

The role of wheat embryo globulin nutrients in improving cognitive dysfunction in AD rats

Neuroinflammation and intestinal microbiota cause pathological progression of Alzheimer's disease (AD), leading to neurodegeneration and cognitive decline. This study investigates the effects of wheat embryo globulin nutrient (WEGN) on depression, neuroinflammation, and intestinal microbial disorder caused by AD and its protective mechanism on cognitive impairment. Results demonstrated that rats in the WEGN group have lower feed intake but higher body weight than those in the control group. Notably, rats in the WEGN group have a higher number of cross grids and uprights and a smaller amount of fecal particles than those in the control group. Biochemical examinations revealed that rats in the WEGN group had lower expression of interleukin-1β, interleukin-6, and tumor necrosis factor α in hippocampus tissue and the expression of genes and proteins related to the TLR4/MyD88/NF-κB signaling pathway in AD rats was down-regulated compared to those in the control group. The 16S rRNA gene sequencing results demonstrated that WEGN treatment inhibits the increase of Erysipelotrichaceae, Erysipelatoclostridium, Erysipelotrichaceae, Corynebacterium, and Frisingicoccus, and the reduction of Lactobacillus in AD rats. WEGN has potential value as a practical food in alleviating neuroinflammation-related diseases such as AD.

Rhizoma Gastrodiae Water Extract Modulates the Gut Microbiota and Pathological Changes of P-TauThr231 to Protect Against Cognitive Impairment in Mice

Gastrodiae Rhizoma and its active constituents are known to exhibit neuroprotective effects in Alzheimer’s disease (AD). However, the effect of Rhizoma Gastrodiae water extract (WERG) on AD and the detailed mechanism of action remain unclear. In this study, the mechanism of action of WERG was investigated by the microbiome–gut–brain axis using a D-galactose (D-gal)/AlCl₃-induced AD mouse model. WERG improved the cognitive impairment of D-gal/AlCl₃-induced mice. The expression level of p-Tau^thr231 in the WERG-H treatment group was decreased, and p-Tau^thr231 was found negative in hippocampal DG, CA1, and CA3 regions. Here, the diversity and composition of the gut microbiota were analyzed by 16sRNA sequencing. WERG-H treatment had a positive correlation with Firmicutes, Bacilli, Lactobacillus johnsonii, Lactobacillus murinus, and Lactobacillus reuteri. Interestingly, the Rikenellaceae-RC9 gut group in the gut increased in D-gal/AlCl₃-induced mice, but the increased L. johnsonii, L. murinus, and L. reuteri reversed this process. This may be a potential mechanistic link between gut microbiota dysbiosis and P-Tau^Thr231 levels in AD progression. In conclusion, this study demonstrated that WERG improved the cognitive impairment of the AD mouse model by enriching gut probiotics and reducing P-Tau^Thr231 levels.

PINK1/Parkin-mediated mitophagy is activated to protect against AFB1-induced immunosuppression in mice spleen

Aflatoxin B₁ (AFB₁) can cause mitochondrial malfunction and immunosuppression in spleen. Mitochondrial damage can lead to oxidative stress and aggravate immune cell dysfunction. Phosphatase and tensin homolog (PTEN)-induced putative kinase1 (PINK1)/ E3 ubiquitin ligase PARK2 (Parkin)-mediated mitophagy can scavenge damaged mitochondria and alleviate oxidative stress to maintain cellular homeostasis. However, the role of PINK1/Parkin-mediated mitophagy in AFB₁-induced immunosuppression in spleen is unclear. In this study, sixty male mice were sensibilized orally with AFB₁ at different concentrations [0, 0.5, 0.75, and 1 mg/kg body weight (BW)] for 28 days, and AFB₁ caused splenic structure injury and immunosuppression, also led to upregulation of PINK1/Parkin-mediated mitophagy in a dose-dependent manner. Subsequently, thirty male WT C57BL/6 N mice and thirty male Parkin knockout (Parkin^-/-) C57BL/6 N mice were sensibilized orally with AFB₁ at 0 or 1 mg/kg BW for 28 days, and Parkin^-/- inhibited mitophagy and further aggravated AFB₁-induced splenic structure injury, immunosuppression, mitochondrial damage and oxidative stress. Collectively, these results indicate that AFB₁ exposure activates PINK1/Parkin-mediated mitophagy, which protects against immunosuppression in spleen.

Targeting brain Renin-Angiotensin System for the prevention and treatment of Alzheimer's disease: Past, present and future

Alzheimer's disease (AD) is a well-known neurodegenerative disease characterized by the presence of two main hallmarks - Tau hyperphosphorylation and Aβ deposits. Notwithstanding, in the last few years the scientific evidence about the drivers of AD have been changing and nowadays age-related vascular alterations and several cardiovascular risk factors have been shown to trigger the development of AD. In this context, drugs targeting the Renin Angiotensin System (RAS), commonly used for the treatment of hypertension, are evidencing a high potential to delay AD development due to their action on brain RAS. Indeed, the ACE 1/Ang II/AT1R axis is believed to be upregulated in AD and to be responsible for deleterious effects such as increased oxidative stress, neuroinflammation, blood-brain barrier (BBB) hyperpermeability, astrocytes dysfunction and a decrease in cerebral blood flow. In contrast, the alternative axis - ACE 1/Ang II/AT2R; ACE 2/Ang (1-7)/MasR; Ang IV/ AT4R(IRAP) - seems to counterbalance the deleterious effects of the principal axis and to exert beneficial effects on memory and cognition. Accordingly, retrospective studies demonstrate a reduced risk of developing AD among people taking RAS medication as well as several in vitro and in vivo pre-clinical studies as it is herein critically reviewed. In this review, we first revise, at a glance, the pathophysiology of AD focused on its classic hallmarks. Secondly, an overview about the impact of the RAS on the pathophysiology of AD is also provided, focused on their four essential axes ACE 1/Ang II/AT2R; ACE 2/Ang (1-7)/MasR; Ang IV/ AT4R(IRAP) and ACE 1/Ang II/AT1R. Finally, the therapeutic potential of available drugs targeting RAS on AD, namely angiotensin II receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs), is highlighted and data supporting this hope will be presented, from in vitro and in vivo pre-clinical to clinical studies.

Optimal Formula of Angelica sinensis Ameliorates Memory Deficits in β-amyloid Protein-induced Alzheimer's Disease Rat Model

OBJECTIVE

Angelica (A.) sinensis is used as a traditional medical herb for the treatment of neurodegeneration, aging, and inflammation in Asia. A. sinensis optimal formula (AOF) is the best combination in A. sinensis that has been screened to rescue the cognitive ability in β-amyloid peptide (Aβ_25-35)-treated Alzheimer's disease (AD) rats. The objective of this study was to investigate the effect of AOF on the learning and memory of AD rats as well as to explore the underlying mechanisms.

METHODS

Male Wistar rats were infused with Aβ_25-35 for AD model induction or saline (negative control). Five groups of AD rats were fed on AOF at 20, 40, or 80 mL/kg every day, donepezil at 0.9 mg/kg every day (positive control), or an equal volume of water (AD model) intragastrically once a day for 4 weeks, while the negative control rats were fed on water. The Morris water maze test was used to evaluate the cognitive function of the rats. The Aβ accumulation, cholinergic levels, and antioxidative ability were detected by ELISA. Additionally, the candidate mechanism was determined by gene sequencing and quantitative real-time polymerase chain reaction.

RESULTS

The results showed that AOF administration significantly ameliorated Aβ_25-35-induced memory impairment. AOF decreased the levels of amyloid-β precursor protein and Aβ in the hippocampus, rescued the cholinergic levels, increased the activity of superoxide dismutase, and decreased the malondialdehyde level. In addition, AOF inhibited the expression of IL1b, Mpo, and Prkcg in the hippocampus.

CONCLUSION

These experimental findings illustrate that AOF prevents the decrease in cognitive function and Aβ deposits in Aβ_25-35-treated rats via modulating neuroinflammation and oxidative stress, thus highlighting a potential therapeutic avenue to promote the co-administration of formulas that act on different nodes to maximize beneficial effects and minimize negative side effects.

Honey bee (Apis mellifera ligustica) acetylcholinesterase enzyme activity and aversive conditioning following aluminum trichloride exposure

Background

Aluminum is the third most prevalent element in the earth’s crust. In most conditions, it is tightly bound to form inaccessible compounds, however in low soil pH, the ionized form of aluminum can be taken up by plant roots and distributed throughout the plant tissue. Following this uptake, nectar and pollen concentrations in low soil pH regions can reach nearly 300 mg/kg. Inhibition of acetylcholinesterase (AChE) has been demonstrated following aluminum exposure in mammal and aquatic invertebrate species. In honey bees, behaviors consistent with AChE inhibition have been previously recorded; however, the physiological mechanism has not been tested, nor has aversive conditioning.

Results

This article presents results of ingested aqueous aluminum chloride exposure on AChE as well as acute exposure effects on aversive conditioning in an Apis mellifera ligustica hive. Contrary to previous findings, AChE activity significantly increased as compared to controls following exposure to 300 mg/L Al3+. In aversive conditioning studies, using an automated shuttlebox, there were time and dose-dependent effects on learning and reduced movement following 75 and 300 mg/L exposures.

Conclusions

These findings, in comparison to previous studies, suggest that aluminum toxicity in honey bees may depend on exposure period, subspecies, and study metrics. Further studies are encouraged at the moderate-high exposure concentrations as there may be multiple variables that affect toxicity which should be teased apart further.

JM-20 treatment prevents neuronal damage and memory impairment induced by aluminum chloride in rats

The number of people with dementia worldwide is estimated at 50 million by 2018 and continues to rise mainly due to increasing aging and population growth. Clinical impact of current interventions remains modest and all efforts aimed at the identification of new therapeutic approaches are therefore critical. Previously, we showed that JM-20, a dihydropyridine-benzodiazepine hybrid molecule, protected memory processes against scopolamine-induced cholinergic dysfunction. In order to gain further insight into the therapeutic potential of JM-20 on cognitive decline and Alzheimer's disease (AD) pathology, here we evaluated its neuroprotective effects after chronic aluminum chloride (AlCl3) administration to rats and assessed possible alterations in several types of episodic memory and associated pathological mechanisms. Oral administration of aluminum to rodents recapitulates several neuropathological alterations and cognitive impairment, being considered a convenient tool for testing the efficacy of new therapies for dementia. We used behavioral tasks to test spatial, emotional- associative and novel object recognition memory, as well as molecular, enzymatic and histological assays to evaluate selected biochemical parameters. Our study revealed that JM-20 prevented memory decline alongside the inhibition of AlCl3 -induced oxidative stress, increased AChE activity, TNF-α and pro-apoptotic proteins (like Bax, caspase-3, and 8) levels. JM-20 also protected against neuronal damage in the hippocampus and prefrontal cortex. Our findings expanded our understanding of the ability of JM-20 to preserve memory in rats under neurotoxic conditions and confirm its potential capacity to counteract cognitive impairment and etiological factors of AD by breaking the progression of key steps associated with neurodegeneration.

Combined exposure of alumina nanoparticles and chronic stress exacerbates hippocampal neuronal ferroptosis via activating IFN-γ/ASK1/JNK signaling pathway in rats

Alumina nanoparticles (AlNPs) exposure causes hippocampal-dependent cognitive dysfunction. However, whether chronic stress exacerbates AlNPs-induced hippocampal lesion and its mechanism remains unclear. This study was aimed to investigate the combined effects and mechanisms of AlNPs and chronic stress on the hippocampal lesion. The behavioral tests demonstrated that combined exposure to AlNPs and chronic restraint stress (CRS) worsened both cognition and depression-like behavior than exposed to AlNPs and CRS alone. Microstructural and ultrastructural observations showed that combined exposure to AlNPs and CRS exacerbated hippocampal damage. Both AlNPs and CRS induced hippocampal neuronal ferroptosis, presenting as iron and glutamate metabolism disorder, GPX4 fluorescence of neurons decrease, LPO and ROS levels increase, and FJB-positive neurons increase. Meanwhile, combined exposure to AlNPs and CRS exacerbated hippocampal neuronal ferroptosis. Mechanism investigation revealed that combined exposure to AlNPs and CRS activated IFN-γ/ASK1/JNK signaling pathway. Furthermore, IFN-γ neutralizing antibody R4-6A2 effectively inhibited the activation of IFN-γ/ASK1/JNK signaling pathway, alleviated hippocampal neuronal ferroptosis and improved cognition ability. ASK1 inhibitor GS-4997 also improved hippocampal neuronal ferroptosis and cognitive dysfunction by inhibiting ASK1/JNK signaling pathway. Together, these results demonstrate that combined exposure to AlNPs and CRS exacerbates hippocampal neuronal ferroptosis via activating IFN-γ/ASK1/JNK signaling pathway.

PINK1/Parkin-Mediated Mitophagy Plays a Protective Role in the Bone Impairment Caused by Aluminum Exposure

The pollution of aluminum (Al) in agricultural production and its wide application in food processing greatly increase the chance of human and animal exposure. Al can accumulate in bone and cause bone diseases by inducing oxidative stress. Mitophagy can maintain normal cell function by degrading damaged mitochondria and scavenging reactive oxygen species. However, the role of mitophagy in the bone impairment caused by Al is unknown. In this study, we demonstrated that PTEN induced putative kinase 1 (PINK1)/ E3 ubiquitin ligase PARK2 (Parkin)-mediated mitophagy was activated in the bone impairment caused by Al in vivo. Then, the Al-induced mitophagy in Parkin-deficient mice and MC3T3-E1 cells were decreased. Meanwhile, Parkin deficiency exacerbated the bone impairment, mitochondrial damage, and oxidative stress under Al exposure, both in vivo and in vitro. In general, the results reveal that Al exposure can activate PINK1/Parkin-mediated mitophagy, and the PINK1/Parkin-mediated mitophagy plays a protective role in the bone impairment caused by Al.

Effects of Long-Acting Testosterone Undecanoate on Behavioral Parameters and Na + , K+-ATPase mRNA Expression in Mice with Alzheimer`s Disease

Previous studies have shown that testosterone attenuates stress-induced mood dysfunction and memory deterioration. However, the exact mechanism is still unknown. This study was conducted to investigate the role of long-term testosterone undecanoate on the behavioral responses in AD induced by AlCl3 + D-galactose administration and the possible alteration of the gene expression level of the Na/K ATPase pump. Adult male mice received AlCl3 in drinking water (10 mg/kg/day) and (D-gal 200 mg/kg/day), subcutaneously for 90 consecutive days, then received a single intramuscular (I.M) injection of castor oil (vehicle) on day 91, while treated groups received a single I.M injection of either low (100 mg/kg/45 days) or high dose (500 mg/kg/45 days) respectively of long-acting testosterone undecanoate on day 91. The time spent in the interaction zone during the open field test, preference index to novel objects in the novel object recognition test, spontaneous alternation percentage (SAP) in Y-maze test, and escape latency time in the Morris water maze test were used to measure the locomotor activity, long-term memory, and spatial memory in mice, respectively. The results showed that testosterone undecanoate treatment improved locomotor activity, improved preference to novel objects, improved spatial memory, and reversed anxiety and depression induced by AlCl3 + D-galactose administration in male mice, suggesting the enhancement of behavioral and memory functions brought by testosterone treatment. Moreover, testosterone undecanoate treatment did alter gene expression levels of Na/K ATPase isoforms in the brain hippocampus. In most cases, altered gene expression was significant and correlated with the observed behavioral changes. Taken together, our findings provide new insight into the effects of long-acting testosterone undecanoate administration on locomotor activity, long-term memory, anxiety, and spatial memory in male mice with Alzheimer's disease.

Alendronate reduces the cognitive and neurological disturbances induced by combined doses of d-galactose and aluminum chloride in mice

Neurological disturbances including cholinergic dysfunction, oxidative stress, neuroinflammation, and cognitive impairments are the well-reported consequences of old age-related disorders like Alzheimer's disease (AD) or dementia. Bisphosphonates were shown to ameliorate dementia in osteoporotic patients, neuroinflammation, and cholinesterase activity in rodents. Thus, the present study has been designed to examine the role of alendronate against cognitive and neurological disturbances in mice induced by a combined oral dose of d-galactose and aluminum chloride (AlCl₃ ) for 6 weeks. d-galactose acts as a senescence agent, whereas AlCl₃ is a neurotoxin and in combination generates neuropathologies and cognitive depletion resembling aging and AD. It was found that memory was markedly impaired in d-galactose + AlCl₃ -treated mice as assessed in different behavioral paradigms. Additionally, d-galactose + AlCl₃ led to neurotoxicity assessed on the basis of neuroinflammation, oxidative stress, glial cell activation, neuronal damage, and augmented GSK-3β level in mice hippocampus. Consequently, alendronate administration orally for 15 days in d-galactose + AlCl₃ -exposed mice prominently reversed all these behavioral and neuropathological changes. These findings show that alendronate can be a potential therapeutic molecule with multiple targets for the management of age-related neurological disorders such as AD.

Evaluation of the effect of thymoquinone in d-galactose-induced memory impairments in rats: Role of MAPK, oxidative stress, and neuroinflammation pathways and telomere length

D-galactose (d-gal) induces aging and memory impairment via oxidative stress and neuroinflammation pathways. This study evaluated the neuroprotective activity of thymoquinone (TQ) against d-gal. d-gal (400 mg/kg, SC), d-gal plus TQ (2.5, 5, 10 mg/kg, i.p.), and TQ alone (2.5 and 10 mg/kg) for 8 weeks were administered to rats. The effect of TQ on learning and memory were studied using the Morris water maze test. Malondialdehyde (MDA) and glutathione (GSH) levels were determined in the hippocampus. The levels of MAPKs (p-ERK/ERK, p-P38/P38), cAMP response elements binding (p-CREB/CREB), advanced glycation end products (AGEs), inflammatory markers (TNFα, IL-1β), glial fibrillary acidic protein (GFAP), and brain-derived neurotrophic factor (BDNF) were analyzed by western blotting. Telomere length was evaluated using real-time PCR. Memory and learning impairment, MDA enhancement, GSH reduction, and neuroinflammation via increasing the TNFα, IL-1β, and GFAP contents were observed in d-gal group. TQ with d-gal, improved memory impairment, reduced oxidative stress, and alleviated neuroinflammation. The elevated level of AGEs decreased by TQ compared to d-gal. No changes were observed in the levels of p-ERK/ERK, p-CREB/CREB, p-P38/P38, BDNF, and telomere length following administration of d-gal or TQ plus d-gal. TQ improved memory deficits of d-gal through anti-oxidative and anti-inflammatory mechanisms.

Lycopene ameliorates chronic stress-induced hippocampal injury and subsequent learning and memory dysfunction through inhibiting ROS/JNK signaling pathway in rats

The natural carotenoid lycopene (LYC) has strong antioxidant and neuroprotective capacities. This study investigated the effects and mechanisms of LYC on chronic stress-induced hippocampal lesions and learning and memory dysfunction. Rats were administered LYC and/or chronic restraint stress (CRS) for 21 days. Morris water maze results demonstrated that LYC prevented CRS-induced learning and memory dysfunction. Histopathological staining and transmission electron microscopy observation revealed that LYC ameliorated CRS-induced hippocampal microstructural and ultrastructural damage. Furthermore, LYC alleviated CRS-induced oxidative stress by reducing reactive oxygen species (ROS) production and enhancing antioxidant enzyme activities. LYC also improved CRS-induced hippocampal mitochondrial dysfunction by recovering mitochondrial membrane potential, and complex I (NADH dehydrogenase) and II (succinate dehydrogenase) activities. Moreover, LYC reduced CRS-induced apoptosis via the mitochondrial apoptotic pathway, and decreased the number of terminal deoxynucleotidyl transferase dUTP nick-end-labeled positive cells. Additionally, western blot analysis demonstrated that LYC inhibited CRS-induced activation of the c-Jun N-terminal kinase (JNK) signaling pathway. Correlation analysis indicated that ROS levels, JNK activation, and the mitochondrial apoptotic pathway were positively correlated. Further investigation of the underlying mechanisms revealed that the ROS scavenger N-acetyl-l-cysteine inhibited CRS-induced JNK activation. Furthermore, the JNK inhibitor SP600125 relieved CRS-induced hippocampal mitochondrial dysfunction, apoptosis via the mitochondrial apoptotic pathway, and learning and memory dysfunction. Together, these results suggest that LYC alleviates hippocampal oxidative stress, mitochondrial dysfunction, and apoptosis by inhibiting the ROS/JNK signaling pathway, thereby improving CRS-induced hippocampal injury and learning and memory dysfunction. This study provides a theoretical basis and new therapeutic strategies for the application of LYC to relieve chronic stress encephalopathy.

Grape Seed Proanthocyanidin Extract Ameliorates Streptozotocin-induced Cognitive and Synaptic Plasticity Deficits by Inhibiting Oxidative Stress and Preserving AKT and ERK Activities

Progressive memory loss and cognitive impairment are the main clinical manifestations of Alzheimer's disease (AD). Currently, there is no effective drug available for the treatment of AD. Previous studies have demonstrated that the cognitive impairment of AD is associated with oxidative stress and the inhibition of AKT and ERK phosphorylation. Grape seed proanthocyanidin extract (GSPE) has been shown to have strong antioxidant effect and can protect the nervous system from oxidative stress damage. This study aimed to investigate the protective effect of GSPE on the cognitive and synaptic impairments of AD using a sporadic AD rat model induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) (ICV-STZ). Rats were treated with GSPE (50, 100, or 200 mg/kg every day) by intragastrical (ig.) administration for continuous 7 weeks, and ICV-STZ (3 mg/kg) was performed on the first day and third day of week 5. Learning and memory abilities were assessed by the Morris water maze (MWM) test at week 8. After behavioral test, hippocampal long-term potentiation (LTP) was recorded, and the levels of malondialdehyde (MDA), superoxide dismutases (SOD), glutathione (GSH) and the protein expression of AKT and ERK were measured in the hippocampus and cerebral cortex of rats. Our study revealed that ICV-STZ significantly impaired the working learning ability and hippocampal LTP of rats, significantly increased the levels of MDA, and decreased the activity of SOD and GSH in the hippocampus and cerebral cortex. In contrast, GSPE treatment prevented the impairment of cognitive function and hippocampal LTP induced by ICV-STZ, decreased the level of MDA, and increased the level of SOD and GSH. Furthermore, Western blot results showed that GSPE treatment could prevent the loss of AKT and ERK activities in the hippocampus and cerebral cortex induced by ICV-STZ. Our findings demonstrate that GSPE treatment could ameliorate the impairment of cognitive ability and hippocampal synaptic plasticity in a rat model of sporadic AD by inhibiting oxidative stress and preserving AKT and ERK activities. Therefore, GSPE may be an effective agent for the treatment of cognitive deficits associated with sporadic AD.

Establishment of the concurrent experimental model of osteoporosis combined with Alzheimer's disease in rat and the dual-effects of echinacoside and acteoside from Cistanche tubulosa

ETHNOPHARMACOLOGICAL RELEVANCE

Cistanche tubulosa is a precious traditional Chinese medicine that has been widely used in the treatment of osteoporosis and Alzheimer's disease. Echinacoside and acteoside are the main active constituents in Cistanche tubulosa that have the pharmacological activities with research value. It has been reported that echinacoside and acteoside could improve the learning and memory ability, promote the proliferation and differentiation of osteoblast.

AIM OF STUDY

Echinacoside and acteoside from Cistanche tubulosa have shown significant activities of anti-osteoporosis and anti-Alzheimer's disease, while these effects have not been studied concurrently in a rat model. The aim of this study was to establish and verify the model of osteoporosis combined with Alzheimer's disease in rat, and to investigate the double effects of echinacoside and acteoside on this concurrent model.

MATERIALS AND METHODS

Three model groups of ovariectomy (OVX), sham surgery with D-galactose and AlCl₃ (D), ovariectomy with D-galactose and AlCl₃ (OVX + D) were set at the same time. The rats in drug treatment groups were ovariectomized. While conducting the intraperitoneal injection of D-galactose and intragastric administration of AlCl₃ in the rats of drug treatment groups, the rats were orally administered echinacoside (90 mg/kg/d), acteoside (90 mg/kg/d) and the positive control drugs of estradiol valerate (0.6 mg/kg/d), donepezil HCl (0.8 mg/kg/d), respectively. After the drug treatment of 8 weeks, Morris Water Maze (MWM) test for 6 days was firstly performed. The rats were then sacrificed to harvest the blood, uteri, femora, tibiae and brain tissues. The serum was used for biochemical tests. The uteri were used for histomorphometry. The right femora were used for Micro-CT and histomorphometry, respectively. The right tibiae were used for biomechanical test. The hippocampus collected on ice box was used for biochemical tests. The brain collected by perfusion was used for histomorphometry.

RESULTS

Compared with Sham group, OVX + D group could significantly reduce the learning and memory ability by causing oxidative damage, impairing neurons in hippocampus and affecting the hydrolysis and synthesis of acetylcholine. Meanwhile, the activities of BALP and TRAP in OVX + D group increased significantly (P < 0.001) as compared to Sham group. In addition, compared with Sham group, the mean bone mineral density obviously decreased (P < 0.05), the trabecular bone mass and microarchitecture were also destroyed significantly in OVX + D group. Furthermore, the maximum load and maximum stress significantly reduced (P < 0.01) and the energy absorption also decreased greatly as compared to Sham group. After administrated with echinacoside and acteoside, the typical pathological features of osteoporosis and Alzheimer's disease were ameliorated.

CONCLUSIONS

The model of osteoporosis combined with Alzheimer's disease in rat was feasible and successfully established. Echinacoside and acteoside also showed some significant effects on this concurrent model, and they could be potential candidates from Cistanche tubulosa with double effects for further study.

Perindopril ameliorates experimental Alzheimer's disease progression: role of amyloid β degradation, central estrogen receptor and hyperlipidemic-lipid raft signaling

Accumulating evidence indicates that over-stimulation of angiotensin-converting enzyme 1 (ACE1) activity is associated with β-amyloid (Aβ) and phosphorylated tau (p-tau)-induced apoptosis, oxido-nitrosative neuroinflammatory stress and neurodegeneration in Alzheimer's disease (AD). Alternatively, activation of the ACE2, the metalloprotease neprilysin (Neutral Endopeptidase; NEP) and the insulin-degrading enzyme (IDE) could oppose the effects of ACE1 activation. We aim to investigate the relationship between ACE1/ACE2/NEP/IDE and amyloidogenic/hyperlipidemic-lipid raft signaling in hyperlipidemic AD model. Induction of AD was performed in ovariectomized female rats with high-fat high fructose diet (HFFD) feeding after 4 weeks following D-galactose injection (150 mg/kg). The brain-penetrating ACE1 inhibitor perindopril (0.5 mg/kg/day, p.o.) was administered on a daily basis for 30 days. Perindopril significantly decreased hippocampal expression of ACE1 and increased expression of ACE2, NEP and IDE. Perindopril markedly decreased Aβ_1-42, improved lipid profile and ameliorated the lipid raft protein markers caveolin1 (CAV1) and flotillin 1 (FLOT1). This was accompanied by decreased expression of p-tau and enhancement of cholinergic neurotransmission, coupled with decreased oxido-nitrosative neuroinflammatory stress, enhancement of blood-brain barrier (BBB) functioning and lower expression of the apoptotic markers glial fibrillary acidic protein (GFAP), Bax and β-tubulin. In addition, perindopril ameliorated histopathological damage and improved learning, cognitive and recognition impairment as well as depressive behavior in Morris water maze, Y maze, novel object recognition and forced swimming tests, respectively. Conclusively, perindopril could improve cognitive defects in AD rats, at least through activation of ACE2/NEP/IDE and inhibition of ACE1 and subsequent modulation of amyloidogenic/hyperlipidemic-lipid raft signaling and oxido-nitrosative stress.

Evaluation of the pre-treatment effect of Centella asiatica medicinal plants on long-term potentiation (LTP) in rat model of Alzheimer's disease

The present study was aimed to investigate the pre-treatment effect of Centella asiatica (CeA) extract on long-term potentiation (LTP) in a rat model of Alzheimer's disease (AD). A total of 32 male Wistar rats weighing 380 ± 30 g were randomly divided into four groups (n = 8). Group 1 (C: Control): the control group. Group 2 (L: Lesion): The nucleus basalis of Meynert (NBM) of rats' brain was bilaterally destroyed by injection of Ibotenic acid. Group 3 (CeA): Animals in this group received the CeA leaf extract for only a period of six weeks. Group 4 (CeA + L): The NBM of rats was destroyed by Ibotenic acid after six weeks of a diet containing the CeA leaf extract. In all groups, LTP was recorded using the electrophysiological technique and fEPSP after high frequency stimulation (HFS). The results showed that the slope and amplitude of PS as well as the sub-curve level significantly increased in the CeA + L group compared with the L and CeA groups. The CeA extract improved and strengthened the slope, amplitude and sub-curve surface of cumulative waves in animals with NBM lesion. The results showed that administration CeA extract for six weeks before induction of NBM lesion and induction of Alzheimer could enhance memory. In other words, the CeA extract had a preventive or protective role. The present study showed that CeA had a protective role for neurons among rats with NBM lesion.

Sattar MA, Kamel FO, Ramadan WS, Alzahrani YA. Possible combined effect of perindopril and Azilsartan in an experimental model of dementia in rats

Renin-angiotensin system exerted deleterious effects on learning and cognitive functions through different mechanisms. The present study has been designed to evaluate the protective effect of perindopril and azilsartan as monotherapy or in combination on aluminum chloride (AlCl3) induced neurobehavioral and pathological changes in Alzheimeric rats. Male Wistar rats were divided into nine groups (n = 6); negative control, AlCl3 treated, vehicle, AlCl3 and Azilsartan (3.5 mg/kg, 7 mg/kg) co-treated, AlCl3 and perindopril (0.5 mg/kg, 1 mg/kg) co-treated, AlCl3 and (Azilsartan 3.5 mg/kg + perindopril 0.5 mg/kg), and AlCl3 and (Azilsartan 7 mg/kg + perindopril 1 mg/kg), all groups were treated for consecutive 60 days. Then, memory function was evaluated by the Y- maze test. Amyloid Peptide - 42 (Aβ-42), Acetylcholinesterase (AChE), Malondialdehyde (MDA), Tumor necrosis factor (TNF-α) and Nitric Oxide (NO) levels in the hippocampus were assessed with (ELISA) kits. The histopathological studies of the hippocampal dentate gyrus (DG) and Cornu Ammonis-3 (CA3) were also performed. Oral administration of either azilsartan and perindopril alone or in combined for 60 days have shown; improvement of cognitive function, significant reduction in the hippocampal levels of Aβ-42, Acetylcholinesterase, Malondialdehyde (MDA), Tumor necrosis factor (TNF-α) and reserved most of histopathological changes in dentate gyrus (DG) and Cornu Ammonis-3 (CA3) that mediated by Alcl3. Our behavioral, biochemical, and histopathological studies indicate that perindopril and azilsartan have neuroprotective effects on the AD model of rats induced by AlCl3, suggesting that perindopril and azilsartan may be a candidate drugs for the treatment of AD.

Cognitive impairments in type 2 diabetes, risk factors and preventive strategies

Mild cognitive impairment (MCI) is a modifiable risk factor in progression of several diseases including dementia and type 2 diabetes. If cognitive impairments are not reversed at an early stage of appearance of symptoms, then the prolonged pathogenesis can lead to dementia and Alzheimer's disease (AD). Therefore, it is necessary to detect the risk factors and mechanism of prevention of cognitive dysfunction at an early stage of disease. Poor lifestyle, age, hyperglycemia, hypercholesterolemia, and inflammation are some of the major risk factors that contribute to cognitive and memory impairments in diabetic patients. Mild cognitive impairment was seen in those individuals of type 2 diabetes, who are on an unhealthy diet. Physical inactivity, frequent alcohol consumptions, and use of packed food products that provides an excess of cheap calories are found associated with cognitive impairment and depression in diabetic patients. Omega fatty acids (FAs) and polyphenol-rich foods, especially flavonoids, can reduce the bad effects of an unhealthy lifestyle; therefore, the consumption of omega FAs and flavonoids may be beneficial in maintaining normal cognitive function. These functional foods may improve cognitive functions by targeting many enzymes and molecules in cells chiefly through their anti-inflammatory, antioxidant, or signaling actions. Here, we provide the current concepts on the risk factors of cognitive impairments in type 2 diabetes and the mechanism of prevention, using omega FAs and bioactive compounds obtained from fruits and vegetables. The knowledge derived from such studies may assist physicians in managing the health care of patients with cognitive difficulties.

Potential effects of rapeseed peptide Maillard reaction products on aging-related disorder attenuation and gut microbiota modulation in d-galactose induced aging mice

As a good flavor enhancer, rapeseed peptide Maillard reaction products (MRPs) were developed, and the effects of MRPs on d-galactose induced aging Kunming mice were investigated for 6 weeks with low (200 mg kg-1 day-1), medium (400 mg kg-1 day-1) and high (800 mg kg-1 day-1) doses. Compared with the natural aging group and d-galactose induced aging mice, the mice with MRP administration showed increases in body weight gain, food intake, organ indexes, feces color and urine fluorescence intensity. MRP intake significantly decreased the MDA content and elevated the activities of CAT, SOD and GSH-Px, and T-AOC in the serum and tissues of the liver, kidney and brain. Additionally, AChE activity was decreased in the brain, while Na+-K+ ATPase and Ca2+-Mg2+ ATPase activity increased in a dose-dependent manner, and decreasing levels of IL-1β, IL-6 and TNF-α were observed in the liver and kidney. Histopathological analysis suggested an attenuation of inflammatory cell infiltration in the liver and kidney without cell necrosis. High-throughput sequencing results revealed that the ratio of Firmicutes to Bacteroidetes increased in MRP groups, and the pathogenic bacteria were significantly inhibited, while some beneficial bacteria were significantly increased in the intestine. Overall, our results indicated that MRP consumption might have potential beneficial effects on postponing the aging process via reducing the oxidative stress and gut microflora modulation.

L-histidine and L-carnosine exert anti-brain aging effects in D-galactose-induced aged neuronal cells

BACKGROUND/OBJECTIVES

Brain aging is a major risk factor for severe neurodegenerative diseases. Conversely, L-histidine and L-carnosine are known to exhibit neuroprotective effects. The aim of this study was to examine the potential for L-histidine, L-carnosine, and their combination to mediate anti-brain aging effects in neuronal cells subjected to D-galactose-induced aging.

MATERIALS/METHODS

The neuroprotective potential of L-histidine, L-carnosine, and their combination was examined in a retinoic acid-induced neuronal differentiated SH-SY5Y cell line exposed to D-galactose (200 mM) for 48 h. Neuronal cell proliferation, differentiation, and expression of anti-oxidant enzymes and apoptosis markers were subsequently evaluated.

RESULTS

Treatment with L-histidine (1 mM), L-carnosine (10 mM), or both for 48 h efficiently improved the proliferation, neurogenesis, and senescence of D-galactose-treated SH-SY5Y cells. In addition, protein expression levels of both neuronal markers (β tubulin-III and neurofilament heavy protein) and anti-oxidant enzymes, glutathione peroxidase-1 and superoxide dismutase-1 were up-regulated. Conversely, protein expression levels of amyloid β (1-42) and cleaved caspase-3 were down-regulated. Levels of mRNA for the pro-inflammatory cytokines, interleukin (IL)-8, IL-1β, and tumor necrosis factor-α were also down-regulated.

CONCLUSIONS

To the best of our knowledge, we provide the first evidence that L-histidine, L-carnosine, and their combination mediate anti-aging effects in a neuronal cell line subjected to D-galactose-induced aging. These results suggest the potential benefits of L-histidine and L-carnosine as anti-brain aging agents and they support further research of these amino acid molecules.

Glucose-mediated protein glycation: Contribution of methanolic extract of Ceratonia siliqua L. in protection and in vitro potential inhibition of acetylcholinesterase

Chronic hyperglycemia presents the major etiology of diabetes mellitus and related complications mainly Alzheimer's disease, via the protein glycation and toxic products generated. In the current study, we investigated the eventual protective effect of the methanolic extract of Ceratonia siliqua L. (CsME) against glucose-mediated glycation in serum bovine albumin. The multi-stage glycation markers, namely fructosamines and advanced glycation end products (AGEs) levels were monitored along with measurement of thiol groups; moreover, the in vitro acetylcholinesterase (AChE) inhibition potential was carried out. HPLC was also assessed. Rutin was the main phenolic compound found in CsME. CsME showed a good capacity to inhibit AGEs, fructosamines and protected thiol groups against glycation. CsME exhibited a great AChE inhibition activity. In the present study, CsME prevented glucose-induced protein glycation, it also exhibited a good inhibition of AChE, suggesting its DM complications such as memory troubles related to AD. PRACTICAL APPLICATIONS: Neurodegenerative disorders ranging from memory troubles to Alzheimer's disease present the most diabetes mellitus complications and mainly attributed to protein glycation process. Currently, there is a strong trend to search for efficient natural sources of glycation and acetylcholinesterase inhibitors to replace the synthetic ones, whose secondary effects were shown. The present article tries to justify scientifically the wide use of Ceratonia siliqua L. in Moroccan folk medicine, demonstrating that the methanolic extract of leaves from this species presents a promising source of new natural compounds inhibiting acetylcholinesterase and acting in vitro against glycation generated compounds. Furthermore, for the first time, Rutin was the main phenolic compound found in this extract, these encouraging results should be coupled with further studies to integrate it in pharmaceutical formulations. As such, this paper should be of interest to a broad readership, including those interested in Biochemistry, Phytochemistry, pharmacology, and neurosciences.

Centella asiatica Protects d-Galactose/AlCl3 Mediated Alzheimer's Disease-Like Rats via PP2A/GSK-3β Signaling Pathway in Their Hippocampus

Alzheimer's disease (AD) is a progressive neurodegenerative disorder more prevalent among the elderly population. AD is characterised clinically by a progressive decline in cognitive functions and pathologically by the presence of neurofibrillary tangles (NFTs), deposition of beta-amyloid (Aβ) plaque and synaptic dysfunction in the brain. Centella asiatica (CA) is a valuable herb being used widely in African, Ayurvedic, and Chinese traditional medicine to reverse cognitive impairment and to enhance cognitive functions. This study aimed to evaluate the effectiveness of CA in preventing d-galactose/aluminium chloride (d-gal/AlCl3) induced AD-like pathologies and the underlying mechanisms of action were further investigated for the first time. Results showed that co-administration of CA to d-gal/AlCl3 induced AD-like rat models significantly increased the levels of protein phosphatase 2 (PP2A) and decreased the levels of glycogen synthase kinase-3 beta (GSK-3β). It was further observed that, CA increased the expression of mRNA of Bcl-2, while there was minimal effect on the expression of caspase 3 mRNA. The results also showed that, CA prevented morphological aberrations in the connus ammonis 3 (CA 3) sub-region of the rat's hippocampus. The results clearly demonstrated for the first time that CA could alleviate d-gal/AlCl3 induced AD-like pathologies in rats via inhibition of hyperphosphorylated tau (P-tau) bio-synthetic proteins, anti-apoptosis and maintenance of cytoarchitecture.

Improvements of symptoms of Alzheimer`s disease by inhibition of the angiotensin system

With ageing of the global society, the frequency of ageing-related neurodegenerative diseases such as Alzheimer`s disease (AD) is on the rise worldwide. Currently, there is no cure for AD, and the four drugs approved for AD only have very small effects on AD symptoms. Consequently, there are enormous efforts worldwide to identify new targets for treatment of AD. Approaches that interfere with classical neuropathologic features of AD, such as extracellular senile plaques formed of aggregated amyloid-beta (Abeta), and intracellular neurofibrillary tangles of hyperphosphorylated tau have not been successful so far. In search for a treatment approach of AD, we found that inhibition of the angiotensin-converting enzyme (ACE) by a centrally acting ACE inhibitor retards symptoms of neurodegeneration, Abeta plaque formation and tau hyperphosphorylation in experimental models of AD. Our approach is currently being investigated in a clinical setting. Initial evidence with AD patients shows that a brain-penetrating ACE inhibitor counteracts the process of neurodegeneration and dementia. Moreover, centrally acting ACE inhibitors given in addition to the standard therapy, cholinesterase inhibition, can improve cognitive function of AD patients for several months. This is one of the most promising results for AD treatment since more than a decade.

Protective Effects of Centella asiatica on Cognitive Deficits Induced by D-gal/AlCl₃ via Inhibition of Oxidative Stress and Attenuation of Acetylcholinesterase Level

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with cholinergic dysfunctions and impaired redox homeostasis. The plant Centella asiatica (CA) is renowned for its nutritional benefits and herbal formulas for promoting health, enhancing cognition, and its neuroprotective effects. The present study aims to investigate the protective role of CA on D-gal/AlCl₃-induced cognitive deficits in rats. The rats were divided into six groups and administered with donepezil 1 mg/kg/day, CA (200, 400, and 800 mg/kg/day) and D-gal 60 mg/kg/day + AlCl₃ 200 mg/kg/day for 10 weeks. The ethology of the rats was evaluated by the Morris water maze test. The levels of acetylcholinesterase (AChE), phosphorylated tau (P-tau), malondialdehyde (MDA) and activities of superoxide dismutase (SOD), in the hippocampus and cerebral cortex were estimated by enzyme-linked immunosorbent assay (ELISA). Additionally, the ultrastructure of the prefrontal cortex of the rats’ was observed using transmission electron microscopy (TEM). Rats administered with D-gal/AlCl₃ exhibited cognitive deficits, decreased activities of SOD, and marked increase in AChE and MDA levels. Further, prominent alterations in the ultrastructure of the prefrontal cortex were observed. Conversely, co-administration of CA with D-gal/AlCl₃ improved cognitive impairment, decreased AChE levels, attenuated the oxidative stress in hippocampus and cerebral cortex, and prevented ultrastructural alteration of neurons in the prefrontal cortex. Irrespective of the dose of CA administered, the protective effects were comparable to donepezil. In conclusion, this study suggests that CA attenuated the cognitive deficits in rats by restoring cholinergic function, attenuating oxidative stress, and preventing the morphological aberrations.

Angelica sinensis Supercritical Fluid CO2 Extract Attenuates D-Galactose-Induced Liver and Kidney Impairment in Mice by Suppressing Oxidative Stress and Inflammation

Angelica sinensis (AS, Danggui in Chinese) is an important herbal component of various traditional formulae for the management of asthenia and its tonic effects. Although AS has been shown to ameliorate cognitive damage and nerve toxicity in D-galactose (D-gal)-elicited senescent mice brain, its effects on liver and kidney injury have not yet been explored. In this work, mice were subjected to hypodermic injection with D-gal (200 mg/kg) and orally gavaged with AS (20, 40, or 80 mg/kg) once a day for 8 successive weeks. Results revealed that AS significantly improved liver and kidney function as assessed by organ index and functional parameters. In addition, AS pretreatment effectively ameliorated the histological deterioration. AS attenuated the MDA level and markedly enhanced the activities and gene expressions of antioxidative enzymes, namely Cu, Zn-SOD, CAT, and GPx. Furthermore, AS markedly inhibited the D-gal-mediated increment of expressions of inflammatory cytokines iNOS, COX-2, IκBα, p-IκBα, and p65 and promoted the IκBα expression level in both hepatic and renal tissues. In sum, AS pretreatment could effectively guard the liver and kidney of mice from D-gal-induced injury, and the underlying mechanism was deemed to be intimately related to attenuating oxidative response and inflammatory stress.

Rational Design and Multibiological Profiling of Novel Donepezil-Trolox Hybrids against Alzheimer's Disease, with Cholinergic, Antioxidant, Neuroprotective, and Cognition Enhancing Properties

A novel series of donepezil-trolox hybrids were designed, synthesized, and evaluated as multifunctional ligands against Alzheimer's disease (AD). Biological assays showed that these derivatives possessed moderate to good inhibitory activities against acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B) as well as remarkable antioxidant effects. The optimal compound 6d exhibited balanced functions with good inhibition against hAChE (IC₅₀ = 0.54 μM) and hMAO-B (IC₅₀ = 4.3 μM), significant antioxidant activity (41.33 μM IC₅₀ by DPPH method, 1.72 and 1.79 trolox equivalent by ABTS and ORAC methods), excellent copper chelation, and Aβ_1-42 aggregation inhibition effect. Furthermore, cellular tests indicated that 6d has very low toxicity and is capable of combating oxidative toxin (H₂O₂, rotenone, and oligomycin-A) induced neurotoxicity. Most importantly, oral administration of 6d demonstrated notable improvements on cognition and spatial memory against scopolamine-induced acute memory deficit as well as d-galactose (d-gal) and AlCl₃ induced chronic oxidative stress in a mouse model without acute toxicity and hepatotoxicity. In summary, both in vitro and in vivo results suggested that 6d is a valuable candidate for the development of a safe and effective anti-Alzheimer's drug.

Protective effects of kinetin against aluminum chloride and D-galactose induced cognitive impairment and oxidative damage in mouse

Increasing evidence indicates that aluminum exposure and oxidative stress play crucial roles in the initiation and development of Alzheimer's disease (AD). Aluminum chloride (AlCl₃) and d-galactose (d-gal) combined treatment of mice is considered as an easy and cheap way to obtain an animal model of AD. Kinetin is a plant cytokinin, which is also reported to exert neuro-protective effects in vivo and in vitro. Thus, in this study, neuro-protective effects of kinetin were investigated in an AD model of mice induced by AlCl₃ and d-gal. The Morris water maze (MWM) test was performed to directly evaluate neuro-protective effects of kinetin on the memory and spatial learning abilities, while the histopathological changes were examined by hematoxylin and eosin (H & E) staining method. To further investigate mechanisms involved, Al content in cortex and hippocampus was determined. In addition, related detection kits were used to determine acetylcholine (ACh) content and activity of acetylcholinesterase (AChE). Activities of anti-oxidative enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), and the content of heme oxygenase-1 (HO-1) were also measured. Besides, the content of oxidative damage bio-markers including 8-iso-prostaglandin F (8-iso-PGF), advanced glycation end products (AGEs) and 8-hydroxy-2-deoxyguanosine (8-OHdG) were determined by ELISA kits. Finally, the distribution of beta-amyloid protein 1-42 (Aβ_1-42) was detected by immunohistochemistry (IHC), while the expression levels of amyloidogenic proteins including β-amyloid precursor protein (APP), β-secretase, γ-secretase and Aβ_1-42 were detected by western blotting (WB) method. Results showed that kinetin improved performance in MWM test, attenuated histopathological changes, reduced Al level in cortex and hippocampus, increased ACh content and decreased AChE activity. In addition, kinetin elevated activities of anti-oxidative enzymes and reduced the levels of oxidative damage biomarkers in AD model of mice. Furthermore, kinetin also increased the content of HO-1, and inhibited the distribution of Aβ_1-42 and the expressions of amyloidogenic proteins (APP, β-secretase, γ-secretase and Aβ_1-42) in brain tissue of AD mice. Our results indicate that kinetin has neuro-protective effects on the AD model of mice induced by AlCl₃ and d-gal, suggesting that kinetin may be a candidate drug for treatment of AD.

The effects of ingested aqueous aluminum on floral fidelity and foraging strategy in honey bees (Apis mellifera)

Pollinator decline is of international concern because of the economic services these organisms provide. Commonly cited sources of decline are toxicants, habitat fragmentation, and parasites. Toxicant exposure can occur through uptake and distribution from plant tissues and resources such as pollen and nectar. Metals such as aluminum can be distributed to pollinators and other herbivores through this route especially in acidified or mined areas. A free-flying artificial flower patch apparatus was used to understand how two concentrations of aluminum (2mg/L and 20mg/L) may affect the learning, orientation, and foraging behaviors of honey bees (Apis mellifera) in Turkey. The results show that a single dose of aluminum immediately affects the floral decision making of honey bees potentially by altering sucrose perception, increasing activity level, or reducing the likelihood of foraging on safer or uncontaminated resource patches. We conclude that aluminum exposure may be detrimental to foraging behaviors and potentially to other ecologically relevant behaviors.

Metal ions influx is a double edged sword for the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a common form of dementia in aged people, which is defined by two pathological characteristics: β-amyloid protein (Aβ) deposition and tau hyperphosphorylation. Although the mechanisms of AD development are still being debated, a series of evidence supports the idea that metals, such as copper, iron, zinc, magnesium and aluminium, are involved in the pathogenesis of the disease. In particular, the processes of Aβ deposition in senile plaques (SP) and the inclusion of phosphorylated tau in neurofibrillary tangles (NFTs) are markedly influenced by alterations in the homeostasis of the aforementioned metal ions. Moreover, the mechanisms of oxidative stress, synaptic plasticity, neurotoxicity, autophagy and apoptosis mediate the effects of metal ions-induced the aggregation state of Aβ and phosphorylated tau on AD development. More importantly, imbalance of these mechanisms finally caused cognitive decline in different experiment models. Collectively, reconstructing the signaling network that regulates AD progression by metal ions may provide novel insights for developing chelators specific for metal ions to combat AD.

Prunella vulgaris L., an Edible and Medicinal Plant, Attenuates Scopolamine-Induced Memory Impairment in Rats

Prunella vulgaris L. is as a major plant in the Chinese traditional functional beverage Guangdong herbal tea for the treatment of fevers, diarrhea, and sore mouth. In this study, ethyl acetate parts of aqueous extracts from P. vulgaris L. (EtOAc-APV) were found to demonstrate potent acetylcholinesterase (AChE) inhibition in vitro. Therefore, this study was designed to further investigate the effects of EtOAc-APV on scopolamine (SCOP)-induced aging rats. Male Wistar rats were randomly divided into four groups (n = 12) and given orally by gavage EtOAc-APV (100 mg/kg) for 3 weeks. SCOP (1 mg/kg, ip) was administered to rats 30 min before starting behavioral tests consecutively for 3 days. EtOAc-APV could attenuate SCOP-induced brain senescence in rats by improving behavioral performance and decreasing brain cell damage, which was associated with a notable reduction in AChE activity and MDA level, as well as an increase in SOD and GPx activities. Additionally, EtOAc-APV administration could reduce the expression of NF-κB and GFAP, which showed an anti-neuroinflammatory effect on the SCOP-treated rat. Overall, the current study highlights P. vulgaris L. as an antidementia dietary supplement.

Aluminium and Acrylamide Disrupt Cerebellum Redox States, Cholinergic Function and Membrane-Bound ATPase in Adult Rats and Their Offspring

Accumulation of aluminium and acrylamide in food is a major source of human exposure. Their adverse effects are well documented, but there is no information about the health problems arising from their combined exposure. The aim of the present study was to examine the possible neurotoxic effects after co-exposure of pregnant and lactating rats to aluminium and acrylamide in order to evaluate redox state, cholinergic function and membrane-bound ATPases in the cerebellum of adult rats and their progeny. Pregnant female rats have received aluminium (50 mg/kg body weight) via drinking water and acrylamide (20 mg/kg body weight) by gavage, either individually or in combination from the 14th day of pregnancy until day 14 after delivery. Exposure to these toxicants provoked an increase in malondialdehyde (MDA) and advanced oxidation protein product (AOPP) levels and a decrease in SOD, CAT, GPx, Na⁺K⁺-ATPase, Mg²⁺-ATPase and AChE activities in the cerebellum of mothers and their suckling pups. A reduction in GSH, NPSH and vitamin C levels was also observed. These changes were confirmed by histological results. Interestingly, co-exposure to these toxicants exhibited synergism based on physical and biochemical variables in the cerebellum of mothers and their progeny.

l-Theanine attenuates cadmium-induced neurotoxicity through the inhibition of oxidative damage and tau hyperphosphorylation

Cadmium (Cd) has long been known to induce neurological degenerative disorders. We studied effects of l-theanine, one of the major amino acid components in green tea, on Cd-induced brain injury in mice. Male ICR mice were intraperitoneally injected with l-theanine (100 or 200mg/kg/day) or saline and after one hour these mice were orally administrated with CdCl₂ (3.75-6mg/kg). The treatment was conducted for 8 weeks. l-Theanine significantly reduced Cd level in the mouse brain and plasma. Cd-induced neuronal cell death in the mouse cortex and hippocampus were apparently inhibited by l-theanine treatment. l-Theanine also decreased the levels of malondialdehyde (MDA) and ROS, and obviously elevated the levels of glutathione (GSH) and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the mouse brain. Hyperphosphorylation of tau protein is proposed to be an early event for the evolution of tau pathology, and may play an important role in Cd-induced neurodegeneration. Our results showed that l-theanine significantly suppressed Cd-induced tau protein hyperphosphorylation at Ser199, Ser202, and Ser396. Mechanism study showed that l-theanine inhibited the activation of glycogen synthase kinase-3β (GSK-3β) which contributed to the hyperphosphorylation of tau and Cd-induced cytotoxicity. Furthermore, l-theanine reduced Cd-induced cytotoxicity possibly by interfering with the Akt/mTOR signaling pathway. In conclusion, our study indicated that l-theanine protected mice against Cd-induced neurotoxicity through reducing brain Cd level and relieved oxidative damage and tau hyperphosphorylation. Our foundings provide a novel insight into the potential use of l-theanine as prophylactic and therapeutic agents for Cd-induced neurodegenerative diseases.

Sodium Tanshinone IIA Sulfonate Attenuates Scopolamine-Induced Cognitive Dysfunctions via Improving Cholinergic System

Sodium Tanshinone IIA sulfonate (STS) is a derivative of Tanshinone IIA (Tan IIA). Tan IIA has been reported to possess neuroprotective effects against Alzheimer's disease (AD). However, whether STS possesses effect on AD remains unclear. This study aims to estimate whether STS could protect against scopolamine- (SCOP-) induced learning and memory deficit in Kunming mice. Morris water maze results showed that oral administration of STS (10 mg/kg and 20 mg/kg) and Donepezil shortened escape latency, increased crossing times of the original position of the platform, and increased the time spent in the target quadrant. STS decreased the activity of acetylcholinesterase (AChE) and increased the activity of choline acetyltransferase (ChAT) in the hippocampus and cortex of SCOP-treated mice. Oxidative stress results showed that STS increased the activity of superoxide dismutase (SOD) and decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) in hippocampus and cortex. In addition, western blot was carried out to detect the expression of apoptosis related proteins (Bcl-2, Bax, and Caspase-3). STS upregulated the protein expression of Bcl-2 and downregulated the proteins expression of Bax and Caspase-3. These results indicated that STS might become a promising therapeutic candidate for attenuating AD-like pathological dysfunction.

Neuroprotective effects of ginseng protein on PI3K/Akt signaling pathway in the hippocampus of D-galactose/AlCl3 inducing rats model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer disease (AD) is a progressive neurodegenerative disease, with progressive memory loss, cognitive deterioration, and behavioral disorders. Ginseng (Panax ginseng C.A. Meyer) is widely used in China to treat various kinds of nervous system disorders. The study aimed to explore the therapeutic effect of ginseng protein (GP) on Alzheimer's disease and its correlation with the PI3K/Akt signaling pathway to understand the mechanism underlying the neuroprotective effect of ginseng.

MATERIAL AND METHODS

The AD rat model was established by intraperitoneally injecting D-galactose [60mg/(kgd)] followed by intragastrically administering AlCl3 [40mg/(kgd)] for 90 days. From day 60, the GP groups were intragastrically administered with GP 0.05 or 0.1g/kg twice daily for 30 days. The ethology of rats was tested by Morris water maze test. The content of Aβ1-42 and p-tau in the hippocampus of rats was detected by enzyme-linked immunosorbent assay. The expression of mRNAs and proteins of PI3K, Akt, phosphorylated Akt (p-Akt), Bcl-2, and Bax in the hippocampus was detected by real-time quantitative reverse transcription polymerase chain reaction and Western blot assay.

RESULTS

GP was found to significantly improve the memory ability of AD rats and prolong the times of crossing the platform and the percentage of residence time in the original platform quadrant of spatial probe test. GP also reduced the content of Aβ1-42 and p-tau and improved the mRNA and protein expression of PI3K, p-Akt/Akt, and Bcl-2/Bax in the hippocampus.

CONCLUSIONS

GP could improve the memory ability and reduce the content of Aβ1-42 and p-tau in AD rats. The anti-AD effects of GP were in part mediated by PI3K/Akt signaling pathway activation.

Effect of Donepezil, Tacrine, Galantamine and Rivastigmine on Acetylcholinesterase Inhibition in Dugesia tigrina

Dugesia tigrina is a non-parasitic platyhelminth, which has been recently utilized in pharmacological models, regarding the nervous system, as it presents a wide sensitivity to drugs. Our trials aimed to propose a model for an in vivo screening of substances with inhibitory activity of the enzyme acetylcholinesterase. Trials were performed with four drugs commercialized in Brazil: donepezil, tacrine, galantamine and rivastigmine, utilized in the control of Alzheimer's disease, to inhibit the activity of acetylcholinesterase. We tested five concentrations of the drugs, with an exposure of 24 h, and the mortality and the inhibition of acetylcholinesterase planarian seizure-like activity (pSLA) and planarian locomotor velocity (pLMV) were measured. Galantamine showed high anticholinesterasic activity when compared to the other drugs, with a reduction of 0.05 μmol·min(-1) and 63% of convulsant activity, presenting screw-like movement and hypokinesia, with pLMV of 65 crossed lines during 5 min. Our results showed for the first time the anticholinesterasic and convulsant effect, in addition to the decrease in locomotion induced by those drugs in a model of invertebrates. The experimental model proposed is simple and low cost and could be utilized in the screening of substances with anticholinesterasic action.

Treatment effects of tanshinone IIA against intracerebroventricular streptozotocin induced memory deficits in mice

Our previous studies demonstrated that tanshinone IIA (tan IIA) has significant protective effects against the neurotoxicity induced by β-amyloid protein (Aβ) in cultured cortical neurons and PC12 cells. This study was designed to investigate the protective effects of tan IIA against memory deficits induced by streptozotocin (STZ) in a model of sporadic Alzheimer's disease (AD). STZ was injected twice intracerebroventrically (3mg/kg ICV) on alternate days (day 1 and day 3) in mice. Daily treatment with tan IIA (20, 40, and 80mg/kg, i.g.) starting from the first dose of STZ for 28 days showed a dose dependent improvement in STZ induced memory deficits as assessed by Morris water maze (MWM) test. Nissl staining results confirmed the protective effects of tan IIA on cerebral cortical and hippocampal neurons damage induced by STZ. In addition, tan IIA markedly reduced STZ induced elevation in acetylcholinesterase (AChE) activity and malondialdehyde (MDA) level, and significantly inhibited STZ induced reduction in superoxide dismutases (SOD) and glutathione peroxidase (GSH-Px) activities in the parietal cortex and hippocampus. Moreover, tan IIA attenuated p38 mitogen activated protein kinase (MAPK) phosphorylation in the parietal cortex and hippocampus. These findings demonstrate that tan IIA prevents STZ induced memory deficits may be attributed to ameliorating neuronal damage, restoring cholinergic function, attenuating oxidative stress and blocking p38 MAPK signal pathway activation. Based on our previous studies, the present study provides further support for the potential use of tan IIA in the treatment of AD.