Gonadotropin elevation is ootoxic to ovulatory oocytes and inhibits oocyte maturation, and activin decoy receptor ActRIIB:Fc therapeutically restores maturation

BACKGROUND

Elevated FSH often occurs in women of advanced maternal age (AMA, age ≥ 35) and in infertility patients undergoing controlled ovarian stimulation (COS). There is controversy on whether high endogenous FSH contributes to infertility and whether high exogenous FSH adversely impacts patient pregnancy rates.

METHODS

The senescence-accelerated mouse-prone-8 (SAMP8) model of female reproductive aging was employed to assess the separate impacts of age and high FSH activity on the percentages (%) of viable and mature ovulated oocytes recovered after gonadotropin treatment. Young and midlife mice were treated with the FSH analog equine chorionic gonadotropin (eCG) to model both endogenous FSH elevation and exogenous FSH elevation. Previously we showed the activin inhibitor ActRIIB:Fc increases oocyte quality by preventing chromosome and spindle misalignments. Therefore, ActRIIB:Fc treatment was performed in an effort to increase % oocyte viability and % oocyte maturation.

RESULTS

The high FSH activity of eCG is ootoxic to ovulatory oocytes, with greater decreases in % viable oocytes in midlife than young mice. High FSH activity of eCG potently inhibits oocyte maturation, decreasing the % of mature oocytes to similar degrees in young and midlife mice. ActRIIB:Fc treatment does not prevent eCG ootoxicity, but it restores most oocyte maturation impeded by eCG.

CONCLUSIONS

FSH ootoxicity to ovulatory oocytes and FSH maturation inhibition pose a paradox given the well-known pro-growth and pro-maturation activities of FSH in the earlier stages of oocyte growth. We propose the FOOT Hypothesis ("FSH OoToxicity Hypothesis), that FSH ootoxicity to ovulatory oocytes comprises a new driver of infertility and low pregnancy success rates in DOR women attempting spontaneous pregnancy and in COS/IUI patients, especially AMA women. We speculate that endogenous FSH elevation also contributes to reduced fecundity in these DOR and COS/IUI patients. Restoration of oocyte maturation by ActRIB:Fc suggests that activin suppresses oocyte maturation in vivo. This contrasts with prior studies showing activin A promotes oocyte maturation in vitro. Improved oocyte maturation with agents that decrease endogenous activin activity with high specificity may have therapeutic benefit for COS/IVF patients, COS/IUI patients, and DOR patients attempting spontaneous pregnancies.

PRG ameliorates cognitive impairment in Alzheimer's disease mice by regulating β-amyloid and targeting the ERK pathway

BACKGROUND

PRG is derived from Phellinus ribis and is a homogeneous polysaccharide with well-defined structural information. PRG was found to have significant in vitro neurotrophic and neuroprotective activities. Thus, PRG might be a potential treatment for Alzheimer's disease. However, the related mechanisms of action are still unclear, so deeper in vivo experimental validation and the potential mechanisms need to be investigated.

PURPOSE

The effects of PRG on AD mice were investigated using Senescence-accelerated SAMP8 mice as an AD model to elucidate the crucial molecular mechanisms.

METHODS

PRG was obtained from Phellinus ribis by water-alcohol precipitation, column chromatography, and ultrafiltration. The Morris water maze and novel object recognition behavioral assays were used to evaluate the effects of PRG in AD mice. Nissl staining, the TUNEL apoptosis assay, and Golgi staining were used to assess brain neuronal cell damage, apoptosis, and neuronal status. Enzyme-linked immunosorbent assays, Western blotting, and immunofluorescence were used to explore the impacts of correlated factors and protein pathways under relevant mechanisms.

RESULTS

The findings suggest that PRG improved learning ability and spatial memory capacity in SAMP8 mice. PRG hastened the disintegration of β-amyloid, reduced the content and abnormal accumulation of the toxic Aβ1-42 protein, and decreased apoptosis. PRG activated the BDNF/ERK/CREB signaling pathway through a cascade, exerted neurotrophic effects, regulated cell proliferation and differentiation, increased neuronal dendritic branching and spine density, and improved synaptic plasticity.

CONCLUSION

PRG promoted β-amyloid degradation to reduce neuronal damage and apoptosis. It exerted neurotrophic effects by activating the BDNF/ERK/CREB pathway, promoting neuronal dendritic branching and dendritic spine growth, regulating cell proliferation and differentiation, and improving synaptic plasticity, which improved AD. Taken together, as a novel natural active polysaccharide with a well-defined structure, PRG affected AD symptoms in senescence-accelerated mice by interacting with multiple targets. The results indicate that PRG is a promising potential anti-AD drug candidate.

Multi-strain probiotics ameliorate Alzheimer's-like cognitive impairment and pathological changes through the AKT/GSK-3β pathway in senescence-accelerated mouse prone 8 mice

BACKGROUND

Alzheimer's disease (AD), the most prevalent type of dementia, still lacks disease-modifying treatment strategies. Recent evidence indicates that maintaining gut microbiota homeostasis plays a crucial role in AD. Targeted regulation of gut microbiota, including probiotics, is anticipated to emerge as a potential approach for AD treatment. However, the efficacy and mechanism of multi-strain probiotics treatment in AD remain unclear.

METHODS

In this study, 6-month-old senescence-accelerated-mouse-prone 8 (SAMP8) and senescence-accelerated-mouse-resistant 1 (SAMR1) were utilized. The SAMP8 mice were treated with probiotic-2 (P2, a probiotic mixture of Bifidobacterium lactis and Lactobacillus rhamnosus) and probiotic-3 (P3, a probiotic mixture of Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus rhamnosus) (1 × 109 colony-forming units) once daily for 8 weeks. Morris water maze (MWM) and novel object recognition (NOR) tests were employed to assess the memory ability. 16S sequencing was applied to determine the composition of gut microbiota, along with detecting serum short-chain fatty acids (SCFAs) concentrations. Neural injury, Aβ and Tau pathology, and neuroinflammation level were assessed through western blot and immunofluorescence. Finally, potential molecular mechanisms was explored through transcriptomic analysis and western blotting.

RESULTS

The MWM and NOR test results indicated a significant improvement in the cognitive level of SAMP8 mice treated with P2 and P3 probiotics compared to the SAMP8 control group. Fecal 16S sequencing revealed an evident difference in the α diversity index between SAMP8 and SAMR1 mice, while the α diversity of SAMP8 mice remained unchanged after P2 and P3 treatment. At the genus level, the relative abundance of ten bacteria differed significantly among the four groups. Multi-strain probiotics treatment could modulate serum SCFAs (valeric acid, isovaleric acid, and hexanoic acid) concentration. Neuropathological results demonstrated a substantial decrease in neural injury, Aβ and Tau pathology and neuroinflammation in the brain of SAMP8 mice treated with P3 and P2. Transcriptomic analysis identified the chemokine signaling pathway as the most significantly enriched signaling pathway between SAMP8 and SAMR1 mice. Western blot test indicated a significant change in the phosphorylation level of downstream AKT/GSK-3β between the SAMP8 and SAMR1 groups, which could be reversed through P2 and P3 treatment.

CONCLUSIONS

Multi-strain probiotics treatment can ameliorate cognitive impairment and pathological change in SAMP8 mice, including neural damage, Aβ and Tau pathology, and neuroinflammation. This effect is associated with the regulation of the phosphorylation of the AKT/GSK-3β pathway.

Differential Epigenetic Changes in the Dorsal Hippocampus of Male and Female SAMP8 Mice: A Preliminary Study

Alzheimer's disease (AD) is the most common age-related neurodegenerative disease characterized by memory loss and cognitive impairment. The causes of the disease are not well understood, as it involves a complex interaction between genetic, environmental, and epigenetic factors. SAMP8 mice have been proposed as a model for studying late-onset AD, since they show age-related learning and memory deficits as well as several features of AD pathogenesis. Epigenetic changes have been described in SAMP8 mice, although sex differences have never been evaluated. Here we used western blot and qPCR analyses to investigate whether epigenetic markers are differentially altered in the dorsal hippocampus, a region important for the regulation of learning and memory, of 9-month-old male and female SAMP8 mice. We found that H3Ac was selectively reduced in male SAMP8 mice compared to male SAMR1 control mice, but not in female mice, whereas H3K27me3 was reduced overall in SAMP8 mice. Moreover, the levels of HDAC2 and JmjD3 were increased, whereas the levels of HDAC4 and Dnmt3a were reduced in SAMP8 mice compared to SAMR1. In addition, levels of HDAC1 were reduced, whereas Utx and Jmjd3 were selectively increased in females compared to males. Although our results are preliminary, they suggest that epigenetic mechanisms in the dorsal hippocampus are differentially regulated in male and female SAMP8 mice.

Yuanzhi Powder inhibits tau pathology in SAMP8 mice: Mechanism research of a traditional Chinese formula against Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Yuanzhi Powder (YZP), a classical Chinese medicine formula, is good at tonifying heart-Qi and improving cognitive ability. YZP has been reported to show therapeutic effect on alleviating the symptoms of Alzheimer's disease (AD).

AIM OF THE STUDY

This study was conducted to observe the effects of YZP on improving the cognitive abilities of SAMP8 mice, and explore the involved mechanisms on inhibiting the excessive accumulation of phosphorylated tau.

MATERIAL AND METHODS

Thirty SAMP8 mice were randomly divided into five groups: AD group, AD + DO group, AD + YZP group, AD + LAC group and AD + LAC + YZP group. Age-matched SAMR1 mice were served as CTL group. AD + LAC group and AD + LAC + YZP group received 1 μg Lactacystin solution via intra-cerebroventricular injection. All mice (except the CTL group and AD + LAC group) were intragastrically administrated for 8 consecutive weeks. Then, the Morris Water Maze (MWM) test was conducted for evaluation of learning and memory abilities. The pathological changes of hippocampal CA1 were observed by Hematoxylin & eosin (H&E) staining. The expression of 26S proteasome in the hippocampus was measured by Western Blot (WB) and immunohistochemistry (IHC). The expressions of total tau (Tau5) and hyperphosphorylated tau (pS199, pT231 and pS396) were detected by WB. The aggregation of hyperphosphorylated tau and the binding ability of tau protein to microtubules were evaluated respectively by immunostaining and Thioflavin-S staining and double-label immunofluorescence.

RESULTS

SAMP8 mice showed serious cognitive impairment in behavioral tests. However, treatment of YZP significantly ameliorated the cognitive deficits of SAMP8 mice. The H&E staining suggested that YZP could protect against neuronal loss in SAMP8 mice. The IHC and WB results showed that YZP increases 26S proteasome expression in SAMP8 mice and 26S proteasome expression was effectively inhibited by Lactacystin. Meanwhile, The WB results demonstrated that YZP can inhibit the expression of hyperphosphorylated tau (pT231, pS396 and pS199). Furthermore, the immunostaining and Thioflavin-S staining and double-label immunofluorescence results indicated that YZP attenuates the excessive aggregation of hyperphosphorylated tau and enhances the binding ability of tau to stabilize microtubules in SAMP8 mice.

CONCLUSIONS

YZP could enhance cognitive performance and learning of AD, ameliorate tau pathology and significantly improve the binding ability of tau to microtubules, based potentially on inhibiting the excessive aggregation of hyperphosphorylated tau via the 26Sproteasome pathway but not necessarily the only one.

Effects of exercise intensity on spatial memory performance and hippocampal synaptic function in SAMP8 mice

Learning and memory impairment is commonly noted in Alzheimer's disease (AD), which is regarded as a progressive synaptic failure disease. Exercise is a nonpharmacological strategy that may help prevent cognitive decline and reduce the risk of AD, which is usually thought to be related to synaptic damage in the hippocampus. However, the effects of exercise intensity on hippocampal memory and synaptic function in AD remain unclear. In this study, senescence-accelerated mouse prone-8 (SAMP8) mice were randomly assigned to the control group (Con), low-intensity exercise group (Low), and moderate-intensity exercise group (Mid). Here, we showed that eight weeks of treadmill exercise beginning in four-month-old mice improved spatial memory and recognition memory in six-month-old SAMP8 mice, while the Con group exhibited impaired spatial memory and recognition memory. Treadmill exercise also improved hippocampal neuron morphology in SAMP8 mice. Furthermore, dendritic spine density and the levels of postsynaptic density protein-95 (PSD95) and Synaptophysin (SYN) increased significantly in the Low and Mid groups as compared with the Con group. We further showed that moderate-intensity exercise (60% of maximum speed) was more efficacious in increasing dendritic spine density、PSD95 and SYN, than low-intensity exercise (40% of maximum speed). In conclusion, the positive effect of treadmill exercise is closely related to exercise intensity, with moderate-intensity exercise showing the most optimal effects.

Effects of Scrophularia buergeriana Extract (Brainon(®)) on Aging-Induced Memory Impairment in SAMP8 Mice

Alzheimer's disease (AD) is a worldwide problem. Currently, there are no effective drugs for AD treatment. Scrophularia buergeriana Miquel (SB) is a traditional herbal medicine used in Korea to treat various diseases. Our previous studies have shown that ethanol extract of SB roots (SBE, Brainon^®) exhibits potent anti-amnesic effects in Aβ_1-42- or scopolamine-treated memory impairment mice model and neuroprotective effects in a glutamate-induced SH-SY5Y cell model. In this study, we evaluated the therapeutic effects of Brainon^® and its mechanism of action in senescence-accelerated mouse prone 8 (SAMP8) mice. Brainon^® (30 or 100 mg/kg/day) was orally treated to six-month-old SAMP8 mice for 12 weeks. Results revealed that Brainon^® administration effectually ameliorated cognitive deficits in Y-maze and passive avoidance tests. Following the completion of behavioral testing, western blotting was performed using the cerebral cortex. Results revealed that Brainon^® suppressed Aβ_1-42 accumulation, Tau hyperphosphorylation, oxidative stress, and inflammation and alleviated apoptosis in SAMP8 mice. Brainon^® also promoted synaptic function by downregulating the expression of AChE and upregulating the expression of p-CREB/CREB and BDNF. Furthermore, Brainon^® restored SAMP8-reduced expression of ChAT and -dephosphorylated of ERK and also decreased AChE expression in the hippocampus. Furthermore, Brainon^® alleviated AD progression by promoting mitophagy/autophagy to maintain normal cellular function as a novel finding of this study. Our data suggest that Brainon^® can remarkably improve cognitive deficiency with the potential to be utilized in functional food for improving brain health.

Probing the relevance of the accelerated aging mouse line SAMP8 as a model for certain types of neuropsychiatric symptoms in dementia

INTRODUCTION

People with dementia (PwD) often present with neuropsychiatric symptoms (NPS). NPS are of substantial burden to the patients, and current treatment options are unsatisfactory. Investigators searching for novel medications need animal models that present disease-relevant phenotypes and can be used for drug screening. The Senescence Accelerated Mouse-Prone 8 (SAMP8) strain shows an accelerated aging phenotype associated with neurodegeneration and cognitive decline. Its behavioural phenotype in relation to NPS has not yet been thoroughly investigated. Physical and verbal aggression in reaction to the external environment (e.g., interaction with the caregiver) is one of the most prevalent and debilitating NPS occurring in PwD. Reactive aggression can be studied in male mice using the Resident-Intruder (R-I) test. SAMP8 mice are known to be more aggressive than the Senescence Accelerated Mouse-Resistant 1 (SAMR1) control strain at specific ages, but the development of the aggressive phenotype over time, is still unknown.

METHODS

In our study, we performed a longitudinal, within-subject, assessment of aggressive behaviour of male SAMP8 and SAMR1 mice at 4, 5, 6 and 7 months of age. Aggressive behaviour from video recordings of the R-I sessions was analysed using an in-house developed behaviour recognition software.

RESULTS

SAMP8 mice were more aggressive relative to SAMR1 mice starting at 5 months of age, and the phenotype was still present at 7 months of age. Treatment with risperidone (an antipsychotic frequently used to treat agitation in clinical practice) reduced aggression in both strains. In a three-chamber social interaction test, SAMP8 mice also interacted more fervently with male mice than SAMR1, possibly because of their aggression-seeking phenotype. They did not show any social withdrawal.

DISCUSSION

Our data support the notion that SAMP8 mice might be a useful preclinical tool to identify novel treatment options for CNS disorders associated with raised levels of reactive aggression such as dementia.

[Effect of electroacupuncture on complement C1q and microglia phagocytosis in hippocampus of SAMP8 mice]

OBJECTIVE

To observe the effect of electroacupuncture (EA) on the expression of Iba-1, complement C1q and CD68 in hippocampus of SAMP8 mice, so as to explore its mechanisms underlying improvement of Alzheimer's disease (AD).

METHODS

Twenty-four male SAMP8 mice were randomly and equally divided into model and EA groups, and 12 SAMR1 mice were used as the control group. EA (2 Hz, 1.5-2.0 mA) was applied to "Baihui" (GV20), "Dazhui"(GV14) and "Shen-shu"(BL23) for 20 min once daily in the EA group, each course of treatment was 8 days, with an interval of 2 days between two courses, and the mice were treated for 3 courses. Morris water maze test was performed to assess the learning-memory ability of mice. The positive expression levels of Iba-1 and CD68 proteins in the hippocampus CA1 region were detected by immunohistochemistry. The mRNA and protein expression levels of Iba-1,C1q and CD68 in the hippocampus were detected by real-time PCR and Western blot, separately.

RESULTS

Compared with the control group, the average escape latency of Morris water maze test was prolonged in the model group (P<0.01), duration of swimming in the original platform quadrant and the number of original platform crossing were significantly shorter and decreased respectively (P<0.01). Compared with the model group, the average escape latency in the EA group was shortened (P<0.05, P<0.01), the duration of swimming in the original platform quadrant and the number of original platform crossing were significantly prolonged and increased (P<0.01). The immunoactivity of Iba-1 and CD68 in hippocampal CA1 region, and mRNA and protein expression levels of hippocampal Iba-1,C1q and CD68 were significantly up-regulated in the model group in contrast to the control group (P<0.01, P<0.05), and obviously down-regulated except the mRNA expression level of hippocampal Iba-1 in the EA group relevant to the model group (P<0.01, P<0.05).

CONCLUSION

EA can improve the learning and memory ability of SAMP8 mice, which may be associated with its effect in inhibiting of complement C1q-dependent microglial phagocytosis in the hippocampus.

Kampo formulas alleviate aging-related emotional disturbances and neuroinflammation in male senescence-accelerated mouse prone 8 mice

Aging-induced neuroinflammation, also known as neuroinflammaging, plays a pivotal role in emotional disturbances, including depression and anxiety, in older individuals, thereby leading to cognitive dysfunction. Although numerous studies have focused on therapeutic strategies for cognitive impairment in older individuals, little research has been performed on treating its preceding emotional disturbances. Here, we examined whether Kampo formulas (kososan [KS], nobiletin-rich kososan [NKS], and hachimijiogan [HJG]) can ameliorate aging-induced emotional disturbances and neuroinflammation in mice. The depression-like behaviors observed in SAMP8 mice, relative to normally aging SAMR1 mice, were significantly prevented by treatment with Kampo formulas for 13 weeks. Western blot analysis revealed that hippocampal neuroinflammation was significantly abrogated by Kampo formulas. KS and NKS also significantly attenuated the hippocampal neuroinflammatory priming induced by lipopolysaccharide (LPS, 0.33 mg/kg, i.p.) challenge in SAMP8 mice. Hippocampal IL-1β, IL-6, and MCP-1 levels were significantly decreased in NKS-treated SAMP8 mice. KS and NKS showed significantly reduced tau accumulation in the brains of SAMP8 mice. RNA-sequencing revealed that each Kampo formula led to unique dynamics of hippocampal gene expression and appeared to abrogate hippocampal inflammatory responses. HJG significantly blocked the LPS-induced increase in serum IL-6 and MCP-1. These results suggest that Kampo formulas would be useful for treating aging-induced depression, in part by regulating neuroinflammatory pathways. This finding may pave the way for the development of therapeutic strategies for aging-related emotional disturbances, which may contribute to the prevention of cognitive dysfunction in older individuals.

Evaluation of the Anti-Aging Effects of a Probiotic Combination Isolated From Centenarians in a SAMP8 Mouse Model

Population aging is a prominent global problem in today’s society. However, there are currently no good methods to treat or prevent aging, so anti-aging research has crucial implications. In this research, we screened bacteria from centenarians, and finally selected four probiotics (Lactobacillus fermentum SX-0718, L. casei SX-1107, Bifidobacterium longum SX-1326, and B. animalis SX-0582) to form a probiotic combination. By using the senescence accelerated mouse prone 8 (SAMP8) model, the anti-aging effects of the probiotic combination were evaluated by using behavioural testing, neuroinflammation, intestinal inflammation, and intestinal microbiota. The results showed that probiotic combination improved the impaired spatial memory, motor dysfunction, and decreased exploratory behavior in aging mice. The probiotic combination inhibited Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NFκB)-induced neuroinflammation and up-regulated the expression of Sirt 1 to protect hippocampal neurons. At the same time, the probiotic combination regulated the intestinal microbiota, reduced the relative abundance of Alistipes and Prevotella in SAMP8 mice, inhibited TLR4/NFκB-induced intestinal inflammation, and increased the expression of intestinal permeability related proteins zonula occludens-1 (ZO-1) and Occuldin. The anti-aging effects of the probiotic combination may be through the regulating intestinal microbiota and inhibiting TLR4/NFκB-induced inflammation. This research provides the basis and technical support for the future production and application of the probiotic combination.

Palmitoylethanolamide Counteracts Enteric Inflammation and Bowel Motor Dysfunctions in a Mouse Model of Alzheimer's Disease

Palmitoylethanolamide (PEA), an endogenous lipid mediator, is emerging as a promising pharmacological agent in multiple neurodegenerative disorders for its anti-inflammatory and neuroprotective properties. However, its effects on enteric inflammation and colonic dysmotility associated with Alzheimer’s disease (AD) are lacking. This study was designed to investigate the beneficial effect of PEA administration in counteracting the enteric inflammation and relieving the bowel motor dysfunctions in an AD mouse model, SAMP8 mice. In addition, the ability of PEA in modulating the activation of enteric glial cells (EGCs), pivotally involved in the pathophysiology of bowel dysfunctions associated with inflammatory conditions, has also been examined. SAMP8 mice at 4 months of age were treated orally with PEA (5 mg/kg/day) for 2 months. SAMR1 animals were employed as controls. At the end of treatment, parameters dealing with colonic motility, inflammation, barrier integrity and AD protein accumulation were evaluated. The effect of PEA on EGCs was tested in cultured cells treated with lipopolysaccharide (LPS) plus β-amyloid 1–42 (Aβ). SAMP8 treated with PEA displayed: 1) an improvement of in vitro colonic motor activity, citrate synthase activity and intestinal epithelial barrier integrity and 2) a decrease in colonic Aβ and α-synuclein (α-syn) accumulation, S100-β expression as well as enteric IL-1β and circulating LPS levels, as compared with untreated SAMP8 mice. In EGCs, treatment with PEA counteracted the increment of S100-β, TLR-4, NF-κB p65 and IL-1β release induced by LPS and Aβ. These results suggest that PEA, under a condition of cognitive decline, prevents the enteric glial hyperactivation, reduces AD protein accumulation and counteracts the onset and progression of colonic inflammatory condition, as well as relieves intestinal motor dysfunctions and improves the intestinal epithelial barrier integrity. Therefore, PEA represents a viable approach for the management of the enteric inflammation and motor contractile abnormalities associated with AD.

The effect and pharmacology of Yizhi Sheng Hui decoction on Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) has gradually increased as society has aged and is now a serious social problem. In the clinical treatment of AD, patients show improvement in cognitive function after treatment with the traditional Chinese medicine compound, Yizhi Sheng Hui (YZSH) decoction. This study systematically investigates the effect and pharmacology of the YZSH decoction on AD.

METHODS

In this study, 24 SAMP8 AD model mice were randomly divided into three groups: an untreated control group, a group treated with the YZSH decoction, and a positive control group treated with donepezil hydrochloride. Eight SAMR1 mice were placed in the normal control group. A Morris water maze test and a step-down test were conducted at 8 and 13 weeks after continuous intragastric administration of the two drugs. After 13 weeks of administration, the hippocampal expression of Aβ1-42 and tau protein were measured.

RESULTS

There was no change in the latent period duration and the number of platform crossings in each group after 8 weeks of administration, but after 13 weeks of administration, the latent period of the treatment group and the positive control group were significantly shorter than the untreated control group. Initially, the SAMP8 mice showed a lower spatial exploration ability than the SAMR1 mice. However, after 13 weeks of administration, the treatment group and the control group exhibited a better exploration ability. Compared with the SAMR1 mice, the on-stage evasion time and step-down errors significantly increased in the untreated group. Compared with the untreated group, mice in the treatment group and the positive control group showed a shorter latent period after 8 weeks of administration, and the on-stage evasion time for both groups was significantly reduced after 13 weeks of administration. The treatment group showed fewer instances of electric shock. Hippocampal expression of Aβ1-42 was high in the untreated group, was much lower in the positive control group, and no Aβ1-42 expression was observed in the treatment group.

CONCLUSIONS

The YZSH decoction improved the learning and memory of mice with AD, related to the inhibition of Aβ1-42 expression.

Microalgae Aurantiochytrium Sp. Increases Neurogenesis and Improves Spatial Learning and Memory in Senescence-Accelerated Mouse-Prone 8 Mice

Much attention has recently been focused on nutraceuticals, with minimal adverse effects, developed for preventing or treating neurological diseases such as Alzheimer's disease (AD). The present study was conducted to investigate the potential effect on neural development and function of the microalgae Aurantiochytrium sp. as a nutraceutical. To test neuroprotection by the ethanol extract of Aurantiochytrium (EEA) and a derivative, the n-Hexane layer of EEA (HEEA), amyloid-β-stimulated SH-SY5Y cells, was used as an in vitro AD model. We then assessed the potential enhancement of neurogenesis by EEA and HEEA using murine ex vivo neurospheres. We also administered EEA or HEEA to senescence-accelerated mouse-prone 8 (SAMP8) mice, a non-transgenic strain with accelerated aging and AD-like memory loss for evaluation of spatial learning and memory using the Morris water maze test. Finally, we performed immunohistochemical analysis for assessment of neurogenesis in mice administered EEA. Pretreatment of SH-SY5Y cells with EEA or the squalene-rich fraction of EEA, HEEA, ameliorated amyloid-β-induced cytotoxicity. Interestingly, only EEA-treated cells showed a significant increase in cell metabolism and intracellular adenosine triphosphate production. Moreover, EEA treatment significantly increased the number of neurospheres, whereas HEEA treatment significantly increased the number of β-III-tubulin+ young neurons and GFAP+ astrocytes. SAMP8 mice were given 50 mg/kg EEA or HEEA orally for 30 days. EEA and HEEA decreased escape latency in the Morris water maze in SAMP8 mice, indicating improved memory. To detect stem cells and newborn neurons, we administered BrdU for 9 days and measured BrdU+ cells in the dentate gyrus, a neurogenic stem cell niche of the hippocampus. In SAMP8 mice, EEA rapidly and significantly increased the number of BrdU+GFAP+ stem cells and their progeny, BrdU+NeuN+ mature neurons. In conclusion, our data in aggregate indicate that EEA and its constituents could be developed into a nutraceutical for promoting brain health and function against several age-related diseases, particularly AD.

Microglial Hyperreactivity Evolved to Immunosuppression in the Hippocampus of a Mouse Model of Accelerated Aging and Alzheimer's Disease Traits

Neuroinflammation is a risk factor for Alzheimer's disease (AD). We sought to study the glial derangement in AD using diverse experimental models and human brain tissue. Besides classical pro-inflammatory cytokines, we analyzed chitinase 3 like 1 (CHI3L1 or YKL40) and triggering receptor expressed on myeloid cells 2 (TREM2) that are increasingly being associated with astrogliosis and microgliosis in AD, respectively. The SAMP8 mouse model of accelerated aging and AD traits showed elevated pro-inflammatory cytokines and activated microglia phenotype. Furthermore, 6-month-old SAMP8 showed an exacerbated inflammatory response to peripheral lipopolysaccharide in the hippocampus and null responsiveness at the advanced age (for this strain) of 12 months. Gene expression of TREM2 was increased in the hippocampus of transgenic 5XFAD mice and in the cingulate cortex of autosomal dominant AD patients, and to a lesser extent in aged SAMP8 mice and sporadic early-onset AD patients. However, gene expression of CHI3L1 was increased in mice but not in human AD brain samples. The results support the relevance of microglia activation in the pathways leading to neurodegeneration and suggest diverse neuroinflammatory responses according to the AD process. Therefore, the SAMP8 mouse model with marked alterations in the dynamics of microglia activation and senescence may provide a complementary approach to transgenic mouse models for the study of the neuroinflammatory mechanisms underlying AD risk and progression.

Adenosine and Metabotropic Glutamate Receptors Are Present in Blood Serum and Exosomes from SAMP8 Mice: Modulation by Aging and Resveratrol

Adenosine (ARs) and metabotropic glutamate receptors (mGluRs) are G-protein coupled receptors (GPCRs) that are modulated in the brain of SAMP8 mice, an animal model of Alzheimer's disease (AD). In the present work, it is shown the presence of ARs and mGluRs in blood serum and derived exosomes from SAMP8 mice as well as its possible modulation by aging and resveratrol (RSV) consumption. In blood serum, adenosine A₁ and A_2A receptors remained unaltered from 5 to 7 months of age. However, an age-related decrease in adenosine level was observed, while 5'-Nucleotidase activity was not modulated. Regarding the glutamatergic system, it was observed a decrease in mGluR₅ density and glutamate levels in older mice. In addition, dietary RSV supplementation caused an age-dependent modulation in both adenosinergic and glutamatergic systems. These GPCRs were also found in blood serum-derived exosomes, which might suggest that these receptors could be released into circulation via exosomes. Interestingly, changes elicited by age and RSV supplementation on mGluR₅ density, and adenosine and glutamate levels were similar to that detected in whole-brain. Therefore, we might suggest that the quantification of these receptors, and their corresponding endogenous ligands, in blood serum could have predictive value for early diagnosis in combination with other distinctive hallmarks of AD.

Resveratrol Differently Modulates Group I Metabotropic Glutamate Receptors Depending on Age in SAMP8 Mice

Glutamate homeostasis is critical for neurotransmission as this excitatory neurotransmitter has a relevant role in cognition functions through ionotropic and metabotropic glutamate receptors in the central nervous system. During the last years, the role of the group I metabotropic glutamate receptors (mGluRs) in neurodegenerative diseases such as Alzheimer's disease has been intensely investigated. Resveratrol (RSV) is a natural polyphenolic compound that is thought to have neuroprotective properties for human health. However, little is known about the action of this compound on mGluR signaling. Therefore, the aim of this study was to investigate the possible modulation of group I mGluRs in SAMP8 mice five and seven months of age supplemented with RSV in the diet. Data reported herein show that RSV plays a different modulatory action on group I mGluRs: mGluR₅ is downregulated as age increases, independently of RSV presence, and mGluR₁ is upregulated or downregulated by RSV treatment depending on age (i.e., depending on mGluR₅ levels). In addition, a neuroprotective role can be inferred for RSV as lower glutamate levels, higher synapsin levels, and unchanged caspase-3 activity were detected after RSV treatment. In conclusion, our findings indicate that RSV treatment modifies the group I mGluR-mediated glutamatergic system in SAMP8 mice, which could contribute to the beneficial effects of this natural polyphenol.

Comparison of the Protective Effects of Ginsenosides Rb1 and Rg1 on Improving Cognitive Deficits in SAMP8 Mice Based on Anti-Neuroinflammation Mechanism

This present study was designed to investigate the different effects of ginsenosides Rb1 and Rg1 on improving cognitive deficits in 4-month-old SAMP8 mice. Mice were divided into six groups, including the SAMP8 group, the SAMP8 + Donepezil (1.6 mg/kg) group, the SAMP8 + Rb1 (30 and 60 µmol/kg), and SAMP8 + Rg1 (30 and 60 µmol/kg) groups. SAMR1 mice of the same age were used as the control group. Ginsenosides and donepezil were administrated orally to animals for 8 weeks, then the learning and memory ability of mice were measured by using Morris water maze (MWM) test, object recognition test and passive avoidance experiments. The possible mechanisms were studied including the anti-glial inflammation of Rb1 and Rg1 using HE staining, immunohistochemistry and western blot experiments. Results revealed that Rb1 and Rg1 treatment significantly improved the discrimination index of SAMP8 mice in the object recognition test. Rb1 (60 µmol/kg) and Rg1 (30, 60 µmol/kg) could significantly shorten the escape latency in the acquisition test of the MWM test in SAMP8 mice. Furthermore, Rb1 and Rg1 treatments effectively reduced the number of errors in the passive avoidance task in SAMP8 mice. Western blot experiments revealed that Rb1 showed higher effect than Rg1 in decreasing protein expression levels of ASC, caspase-1 and Aβ in the hippocampus of SAMP8 mice, while Rg1 was more effective than Rb1 in decreasing the protein levels of iNOS. In addition, although Rb1 and Rg1 treatments showed significant protective effects in repairing neuronal cells loss and inhibiting the activation of astrocyte and microglia in hippocampus of SAMP8 mice, Rb1 was more effective than Rg1. These results suggest that Rb1 and Rg1 could improve the cognitive impairment in SAMP8 mice, and they have different mechanisms for the treatment of Alzheimer's disease.

Green Nut Oil or DHA Supplementation Restored Decreased Distribution Levels of DHA Containing Phosphatidylcholines in the Brain of a Mouse Model of Dementia

Dementia is a major public health concern nowadays. Reduced levels of brain docosahexaenoic acid (DHA) and DHA-phosphatidylcholines (DHA-PCs) in dementia patients were reported previously. Recently, we have reported that supplementation of green nut oil (GNO) or DHA improves memory function and distribution levels of brain DHA in senescence accelerated mice P8 (SAMP8). GNO is extracted from Plukenetia volubilis seeds, and SAMP8 is a well-known model mouse of dementia. In this current study, we examined the results of GNO or DHA supplementation in the distribution levels of brain DHA-PCs in same model mouse of dementia using desorption electrospray ionization (DESI) mass spectrometry imaging (MSI). We observed significantly decreased distribution of brain DHA-PCs, PC (16:0_22:6), and PC (18:0_22:6) in SAMP8 mice compared to wild type mice, and GNO or DHA treatment restored the decreased distribution levels of PC (16:0_22:6) and PC (18:0_22:6) in the brain of SAMP8 mice. These results indicate that GNO or DHA supplementation can ameliorate the decreased distribution of brain DHA-PCs in dementia, and could be potentially used for the prevention and treatment of dementia.

Probiotics modulate the microbiota-gut-brain axis and improve memory deficits in aged SAMP8 mice

ProBiotic-4 is a probiotic preparation composed of Bifidobacterium lactis, Lactobacillus casei, Bifidobacterium bifidum, and Lactobacillus acidophilus. This study aims to investigate the effects of ProBiotic-4 on the microbiota–gut–brain axis and cognitive deficits, and to explore the underlying molecular mechanism using senescence-accelerated mouse prone 8 (SAMP8) mice. ProBiotic-4 was orally administered to 9-month-old SAMP8 mice for 12 weeks. We observed that ProBiotic-4 significantly improved the memory deficits, cerebral neuronal and synaptic injuries, glial activation, and microbiota composition in the feces and brains of aged SAMP8 mice. ProBiotic-4 substantially attenuated aging-related disruption of the intestinal barrier and blood–brain barrier, decreased interleukin-6 and tumor necrosis factor-α at both mRNA and protein levels, reduced plasma and cerebral lipopolysaccharide (LPS) concentration, toll-like receptor 4 (TLR4) expression, and nuclear factor-κB (NF-κB) nuclear translocation in the brain. In addition, not only did ProBiotic-4 significantly decreased the levels of γ-H2AX, 8-hydroxydesoxyguanosine, and retinoic-acid-inducible gene-I (RIG-I), it also abrogated RIG-I multimerization in the brain. These findings suggest that targeting gut microbiota with probiotics may have a therapeutic potential for the deficits of the microbiota–gut–brain axis and cognitive function in aging, and that its mechanism is associated with inhibition of both TLR4-and RIG-I-mediated NF-κB signaling pathway and inflammatory responses.

Ligustilide improves aging-induced memory deficit by regulating mitochondrial related inflammation in SAMP8 mice

Alzheimer’s disease (AD) is an age-related neurodegenerative disease. The main active component in Angelica sinensis, ligustilide, has been reported to have the protective effect on AD. Whether ligustilide could protect against age-induced dementia is still unknown. In this study, we used an aging model, SAMP8 mice to investigate the neuroprotective effect of ligustilide. The behavioral tests (Morris water maze, object recognition task, open field test and elevated plus maze) results showed that ligustilide could improve the memory deficit in SAMP8 mice. For mechanism study, we found that the protein level of P-Drp1 (fission) was decreased and the levels of Mfn1 and Mfn2 (fusion) were increased after ligustilide treatment in animals and cells. Ligustilide increased P-AMPK and ATP levels. Malondialdehyde and superoxide dismutase activity results indicated that ligustilide exerts antioxidant effects by reducing the level of oxidative stress markers. In addition, ligustilide improved neural function and alieved apoptosis and neuroinflammation. These findings have shown that ligustilide treatment improves mitochondrial function in SAMP8 mice, and improves memory loss.

Transcriptome analysis of the hippocampus in environmental noise-exposed SAMP8 mice reveals regulatory pathways associated with Alzheimer's disease neuropathology

Background

Chronic noise exposure is one environmental hazard that is associated with genetic susceptibility factors that increase Alzheimer’s disease (AD) pathogenesis. However, the comprehensive understanding of the link between chronic noise stress and AD is limited. Herein, we investigated the effects of chronic noise exposure on AD-like changes in senescence-accelerated mouse prone 8 (SAMP8).

Methods

A total of 30 male SAMP8 mice were randomly divided into the noise-exposed group, the control group, and aging group (positive controls), and mice in the exposure group were exposed to 98 dB SPL white noise for 30 consecutive days. Transcriptome analysis and AD-like neuropathology of hippocampus were examined by RNA sequencing and immunoblotting. Enzyme-linked immunosorbent assay and real-time PCR were used to further determine the differential gene expression and explore the underlying mechanisms of chronic noise exposure in relation to AD at the genome level.

Results

Chronic noise exposure led to amyloid beta accumulation and increased the hyperphosphorylation of tau at the Ser202 and Ser404 sites in young SAMP8 mice; similar observations were noted in aging SAMP8 mice. We identified 21 protein-coding transcripts that were differentially expressed: 6 were downregulated and 15 were upregulated after chronic noise exposure; 8 genes were related to AD. qPCR results indicated that the expression of Arc, Egr1, Egr2, Fos, Nauk1, and Per2 were significantly high in the noise exposure group. These outcomes mirrored the results of the RNA sequencing data.

Conclusions

These findings further revealed that chronic noise exposure exacerbated aging-like impairment in the hippocampus of the SAMP8 mice and that the protein-coding transcripts discovered in the study may be key candidate regulators involved in environment-gene interactions.

Chronic high fat feeding paradoxically attenuates cerebral capillary dysfunction and neurovascular inflammation in Senescence-Accelerated-Murine-Prone Strain 8 mice

Background: A body of epidemiological, clinical and preclinical studies suggest increased risk for cerebro- and cardio-vascular disease associated with dietary ingestion of long-chain saturated fatty acids (LCSFA). In wild-type rodent models, chronic ingestion of LCSFA diets are associated with increased cerebral capillary permeability, heightened neurovascular inflammation and poorer cognitive performance. However, recent studies suggest that diets enriched in fat may paradoxically attenuate elements of the ageing phenotype via a caloric support axis.Objective: The purpose of this study was to explore the effects of dietary LCSFA on cerebral capillary integrity and neurovascular inflammation in an established model of accelerated ageing, Senescence-Accelerated-Murine-Prone Strain 8 (SAMP8) mice.Methods: From 6 weeks of age, SAMP8 mice and age-matched controls were randomised to either normal chow, or to an LCSFA-enriched diet, for either 12 or 34 weeks. An additional group of SAMP8 mice were provided the LCSFA-enriched diet for 12 weeks followed by the provision of ordinary low-fat chow for 22 weeks. Ex vivo measures of cerebrovascular integrity, neurovascular inflammation and astrocytic activation, were determined via 3-dimensional immunofluorescent confocal microscopy methodologies.Results: LCSFA-fed SAMP8 mice had markedly attenuated cerebral capillary dysfunction concomitant with reduced microglial activation. In SAMP8 mice transiently maintained on an LCSFA diet for 12 weeks, suppression of neurovascular inflammation persisted. Marked hippocampal astrogliosis was evident in LCSFA-fed mice when compared to SAMP8 mice maintained on ordinary chow.Conclusion: The findings from this study support the notion that high-fat, potentially ketogenic diets, may confer neuroprotection in SAMP8 mice through a vascular-support axis.

Effects of Baicalein on Cortical Proinflammatory Cytokines and the Intestinal Microbiome in Senescence Accelerated Mouse Prone 8

Baicalein, a flavonoid derived from the roots of Scutellariae baicalensis Georgi, has shown health benefits for an array of human diseases including dementia. The senescence-accelerated mouse prone 8 (SAMP8) strain is extensively used as a senile dementia model. To further investigate the effects of baicalein in SAMP8 mice, behavioral testing, biochemical detection, and gut microbiota analysis were performed. The results demonstrated that treatment with baicalein ameliorated the senescence status of the SAMP8 mice, as manifested by reducing the grading score of senescence. Additionally, baicalein improved the cognitive functions of the SAMP8 mice, including spatial learning and memory abilities, object recognition memory, and olfactory memory. Furthermore, baicalein significantly inhibited the release of proinflammatory cytokines such as interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and tumor necrosis factor-α (TNF-α) in the brain cortex of SAMP8 mice. Gut microbiota analysis revealed that treatment with baicalein markedly altered the abundance of six genera in SAMP8 mice. Correlation analysis indicated that the abundances of Mucispirillum, Bacteroides, and Sutterella were negatively correlated with cognitive abilities and that Christensenellaceae was positively correlated with cognition. Furthermore, the abundance of Christensenellaceae was negatively correlated with the levels of IL-6 and TNF-α, while [ Prevotella] was positively correlated with the levels of IL-1β and IL-6. In addition, Mucispirillum and Bacteroides were positively correlated with the level of IL-6 in the brain cortex. These data indicated that baicalein ameliorates senescence status and improves cognitive function in SAMP8 mice and that this effect might be attributable to suppression of cortical proinflammatory cytokines and modulation of the intestinal microbiome.

[Effects of serums containing Buzhong Yiqi decoction with Astragalus Radix or Hedysari Radix on anti-immunosenescence in spleen lymphocytes of SAMP8 mice]

This paper was aimed to compare the effect of Buzhong Yiqi decoction containing Hedysari Radix or Astragali Radix on anti-immunosenescence effects in spleen lymphocytes of senescence accelerated mouse 8 (SAMP8). The effect of the serums on the proliferation of spleen T lymphocytes in SAMP8 mice induced by ConA was tested by MTT. The effect of the serums on the T lymphocytes subsets of SAMP8 mice was measured by flow cytometry. ELISA was used to detect the level of IL-2 and IFN-γ in the culture supernatants of spleen lymphocytes. The effect of the serums on the expression of CD28 mRNA in spleen T lymphocytes was detected by fluorescent quantitative PCR. Western blot was used to detect the expression of CD28 protein in spleen T lymphocytes of SAMP8 mice. Both the serums of Buzhong Yiqi decoctions containing Hedysari Radix or Astragali Radix improved the proliferation of T lymphocytes in SAMP8 mice. Both the serums had no obvious effect on the differentiation of spleen T lymphocytes'subsets in SAMP8 mice. Both the serums increased the content of IL-2 and INF-γ in the culture supernatants of spleen lymphocytes. And for the content of IL-2, the serum of Buzhong Yiqi decoction with Hedysari Radix was better（P<0.05）. Both the serums improved the expression of CD28 mRNA in spleen T lymphocytes of SAMP8 mice. And the effect of Hedysari Radix group was better than that of Astragalus Radix group（P<0.05）. Both the serums improved the expression of CD28 protein in spleen T lymphocytes of SAMP8 mice. The role of the serums containing Buzhong Yiqi decoction with Astragalus Radix and the decoction with Hedysari Radix in anti-immunosenescence was through the effect of the CD28. And the effect of Hedysari Radix group was better than that of Astragalus Radix group on improved the expression of CD28 mRNA in T lymphocytes of SAMP8 mice. Astragalus Radix and Hedysari Radix could swap in the aspect of anti-immunosenescence.

Protective effect of resveratrol against light-induced retinal degeneration in aged SAMP8 mice

Purpose

The purpose of this study was to determine the protective effects of Resveratrol (RESV) on acute bright light-induced retinal degeneration in aged senescence accelerated mouse strain.

Methods

Ten three-month-old male SAMP8 mice (prone to aging) were randomly assigned to two experimental dietary groups: one untreated group and one RESV treatment group (n=20 eyes for each group). After 30 days of treatment, mice were exposed to intense bright light. Ten male SAMR1 mice (resistant to aging) served as control (n=20 eyes). The protective effects of RESV administration on light-induced retinal degeneration in SAMP8 strain as well as the effect of bright light damage in the retinas of SAMP8 mice were analyzed by electroretinography (ERG), retinal histology, mRNA, protein and lipid profile.

Results

68%-85% of a-wave amplitude and 72%-92% of b-wave amplitude were persevered by RESV in SAMP8 mice that were exposed to light damage. Also, RESV preserved their photoreceptor nuclei. mRNA expression of neuroprotective factors leukemia inhibitory factor (LIF), brain derived neurotrophic factor (BDNF), oncostatin M (OSM), cardiotrophin 1(CT-1) and cardiotrophin-like cytokine (CLC) were up-regulated 28, 8, 7, 5 and 9-fold in SAMP8 mice after RESV treatment. In addition, RESV could suppress the NF-κB pathway by down-regulating the expression of pIκB. Light damage led to increase of saturated FA, monoenoic FA, n6 PUFA and n6/n3 ratio and decrease of Docosahexaenoic acid (DHA). There was no significant difference on DHA and the ratio of n6/n3-FA between the untreated and RESV treated SAMP8 mice.

Conclusions

Collectively, our study provides evidence that RESV prevents light-induced retinal damage associated with aging.

Cognitive-enhancing effects of hydrolysate of polygalasaponin in SAMP8 mice

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.

Effect of the oral administration of nanoencapsulated quercetin on a mouse model of Alzheimer's disease

Quercetin has been identified as a promising compound with a neuroprotective potential against age-related neurodegenerative diseases such as Alzheimer's disease (AD). Nevertheless, the clinical application of quercetin is hampered by its low oral bioavailability. The aim of this work was to evaluate the capability of nanoencapsulated quercetin in zein nanoparticles (NPQ), that significantly improves the oral absorption and bioavailability of the flavonoid, as potential oral treatment for AD. For this purpose, SAMP8 mice were orally treated for two months with either NPQ (25mg/kg every 48h) or a solution of quercetin (Q; 25mg/kg daily). NPQ displayed a size of 260nm and a payload of about 70μg/mg. For Q, no significant effects were observed in animals. On the contrary, the oral administration of NPQ improved the cognition and memory impairments characteristics of SAMP8 mice. These observations appeared to be related with a decreased expression of the hippocampal astrocyte marker GFAP. Furthermore, significant levels of quercetin were quantified in the brain of mice treated with nanoparticles. These findings highlight the potential of zein nanoparticles to promote the oral absorption of quercetin as well as the therapeutic potential of this flavonoid in AD pathogenesis.

Modulation of brain PUFA content in different experimental models of mice

The relative amounts of arachidonic acid (AA) and docosahexaenoic acid (DHA) govern the different functions of the brain. Their brain levels depend on structures considered, on fatty acid dietary supply and the age of animals. To have a better overview of the different models available in the literature we here compared the brain fatty acid composition in various mice models (C57BL/6J, CD1, Fat-1, SAMP8 mice) fed with different n-3 PUFA diets (deficient, balanced, enriched) in adults and aged animals. Our results demonstrated that brain AA and DHA content is 1) structure-dependent; 2) strain-specific; 3) differently affected by dietary approaches when compared to genetic model of PUFA modulation; 4) different in n-3 PUFA deficient aged C57BL6/J when compared to SAMP8 mouse model of aging. From these experiments, we highlight the difficulty to compare results obtained in different mouse models, different strains, different brain regions and different ages.

Effect of botanical extracts containing carnosic acid or rosmarinic acid on learning and memory in SAMP8 mice

Oxidative damage is one of the hallmarks of the aging process. The current study evaluated effects of two proprietary antioxidant-based ingredients, rosemary extract and spearmint extract containing carnosic acid and rosmarinic acid, respectively, on learning and memory in the SAMP8 mouse model of accelerated aging. The two rosemary extracts contained carnosic acid (60% or 10% carnosic acid) and one spearmint extract contained 5% rosmarinic acid. Three doses of actives in each extract were tested: 32, 16, 1.6 or 0mg/kg. After 90days of treatment mice were tested in T-maze foot shock avoidance, object recognition and lever press. Rosemary extract containing 60% carnosic acid improved acquisition and retention in T-maze foot shock, object recognition and lever press. Rosemary extract with 10% carnosic acid improved retention in T-maze foot shock avoidance and lever press. Spearmint with 5% rosmarinic acid improved acquisition and retention in T-maze foot shock avoidance and object recognition. 4-hydroxynonenal (HNE) was reduced in the brain cortex after treatment with all three extracts (P<0.001) compared to the vehicle treated SAMP8. Protein carbonyls were reduced in the hippocampus after administration of rosemary with 10% carnosic acid (P<0.05) and spearmint containing 5% rosmarinic acid (P<0.001). The current results indicate that the extracts from spearmint and rosemary have beneficial effects on learning and memory and brain tissue markers of oxidation that occur with age in SAMP8 mice.

Tong Luo Jiu Nao, a Chinese Medicine Formula, Reduces Inflammatory Stress in a Mouse Model of Alzheimer's Disease

AIM

The aim of this study is to extend the molecular mechanism of Tong Luo Jiu Nao (TLJN) for Alzheimer's disease (AD), which is a modern Chinese formula that has been used to treat AD.

METHODS

The senescence-accelerated mouse prone 8 strain (SAMP8) is one of the most appropriate models to study the mechanism that underlies AD. The levels of plasma amyloid β (Aβ) and the Aβ deposits were measured using enzyme-linked immunosorbent assay and immunohistochemistry. Immunoblotting was used to observe the effect of TLJN on inflammatory mediator expression in an senescence-accelerated mouse model of AD.

RESULTS

Our data showed that the TLJN-treated groups exhibited a reduction in plasma Aβ levels and reduced Aβ expression. Moreover, TLJN effectively attenuated Aβ-induced activation of extracellular signal-regulated kinase and c-Jun N-terminal kinases and blocked changes in inflammatory mediator expression.

CONCLUSION

These data suggest that TLJN might have protective effects and could potentially act to attenuate inflammatory stress in the pathogenesis of AD.

A comprehensive multiomics approach toward understanding the relationship between aging and dementia

Because age is the greatest risk factor for sporadic Alzheimer's disease (AD), phenotypic screens based upon old age-associated brain toxicities were used to develop the potent neurotrophic drug J147. Since certain aspects of aging may be primary cause of AD, we hypothesized that J147 would be effective against AD-associated pathology in rapidly aging SAMP8 mice and could be used to identify some of the molecular contributions of aging to AD. An inclusive and integrative multiomics approach was used to investigate protein and gene expression, metabolite levels, and cognition in old and young SAMP8 mice. J147 reduced cognitive deficits in old SAMP8 mice, while restoring multiple molecular markers associated with human AD, vascular pathology, impaired synaptic function, and inflammation to those approaching the young phenotype. The extensive assays used in this study identified a subset of molecular changes associated with aging that may be necessary for the development of AD.

Regulation of the p19(Arf)/p53 pathway by histone acetylation underlies neural stem cell behavior in senescence-prone SAMP8 mice

Brain aging is associated with increased neurodegeneration and reduced neurogenesis. B1/neural stem cells (B1-NSCs) of the mouse subependymal zone (SEZ) support the ongoing production of olfactory bulb interneurons, but their neurogenic potential is progressively reduced as mice age. Although age-related changes in B1-NSCs may result from increased expression of tumor suppressor proteins, accumulation of DNA damage, metabolic alterations, and microenvironmental or systemic changes, the ultimate causes remain unclear. Senescence-accelerated-prone mice (SAMP8) relative to senescence-accelerated-resistant mice (SAMR1) exhibit signs of hastened senescence and can be used as a model for the study of aging. We have found that the B1-NSC compartment is transiently expanded in young SAMP8 relative to SAMR1 mice, resulting in disturbed cytoarchitecture of the SEZ, B1-NSC hyperproliferation, and higher yields of primary neurospheres. These unusual features are, however, accompanied by premature loss of B1-NSCs. Moreover, SAMP8 neurospheres lack self-renewal and enter p53-dependent senescence after only two passages. Interestingly, in vitro senescence of SAMP8 cells could be prevented by inhibition of histone acetyltransferases and mimicked in SAMR1 cells by inhibition of histone deacetylases (HDAC). Our data indicate that expression of the tumor suppressor p19, but not of p16, is increased in SAMP8 neurospheres, as well as in SAMR1 neurospheres upon HDAC inhibition, and suggest that the SAMP8 phenotype may, at least in part, be due to changes in chromatin status. Interestingly, acute HDAC inhibition in vivo resulted in changes in the SEZ of SAMR1 mice that resembled those found in young SAMP8 mice.

Antisense oligonucleotide against GSK-3β in brain of SAMP8 mice improves learning and memory and decreases oxidative stress: Involvement of transcription factor Nrf2 and implications for Alzheimer disease

Glycogen synthase kinase (GSK)-3β is a multifunctional protein that has been implicated in the pathological characteristics of Alzheimer's disease (AD), including the heightened levels of neurofibrillary tangles, amyloid-beta (Aβ), and neurodegeneration. In this study we used 12-month-old SAMP8 mice, an AD model, to examine the effects GSK-3β may cause regarding the cognitive impairment and oxidative stress associated with AD. To suppress the level of GSK-3β, SAMP8 mice were treated with an antisense oligonucleotide (GAO) directed at this kinase. We measured a decreased level of GSK-3β in the cortex of the mice, indicating the success of the antisense treatment. Learning and memory assessments of the SAMP8 mice were tested post-antisense treatment using an aversive T-maze and object recognition test, both of which observably improved. In cortex samples of the SAMP8 mice, decreased levels of protein carbonyl and protein-bound HNE were measured, indicating decreased oxidative stress. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a transcription factor known to increase the level of many antioxidants, including glutathione-S transferase (GST), and is negatively regulated by the activity of GSK-3β. Our results indicated the increased nuclear localization of Nrf2 and level of GST, suggesting the increased activity of the transcription factor as a result of GSK-3β suppression, consistent with the decreased oxidative stress observed. Consistent with the improved learning and memory, and consistent with GSK-3b being a tau kinase, we observed decreased tau phosphorylation in brain of GAO-treated SAMP8 mice compared to that of RAO-treated SAMP8 mice. Lastly, we examined the ability of GAO to cross the blood-brain barrier and determined it to be possible. The results presented in this study demonstrate that reducing GSK-3 with a phosphorothionated antisense against GSK-3 improves learning and memory, reduces oxidative stress, possibly coincident with increased levels of the antioxidant transcriptional activity of Nrf2, and decreases tau phosphorylation. Our study supports the notion of GAO as a possible treatment for AD.