Cannabidiol improves the cognitive function of SAMP8 AD model mice involving the microbiota-gut-brain axis.

Cannabidiol (CBD), a natural component extracted from Cannabis sativa L. exerts neuroprotective, antioxidant, and anti-inflammatory effects in Alzheimer's disease (AD), a disease characterized by impaired cognition and accumulation of amyloid-B peptides (Aß). Interactions between the gut and central nervous system (microbiota-gut-brain axis) play a critical role in the pathogenesis of neurodegenerative disorder AD. At present investigations into the mechanisms underlying the neuroprotective action of CBD in AD are not conclusive. The aim of this study was thus to examine the influence of CBD on cognition and involvement of the microbiota-gut-brain axis using a senescence-accelerated mouse prone 8 (SAMP8) model. Data demonstrated that administration of CBD to SAMP8 mice improved cognitive function as evidenced from the Morris water maze test and increased hippocampal activated microglia shift from M1 to M2. In addition, CBD elevated levels of Bacteriodetes associated with a fall in Firmicutes providing morphologically a protective intestinal barrier which subsequently reduced leakage of intestinal toxic metabolites. Further, CBD was found to reduce the levels of hippocampal and colon epithelial cells lipopolysaccharide (LPS), known to be increased in AD leading to impaired gastrointestinal motility, thereby promoting neuroinflammation and subsequent neuronal death. Our findings demonstrated that CBD may be considered a beneficial therapeutic drug to counteract AD-mediated cognitive impairment and restore gut microbial functions associated with the observed neuroprotective mechanisms.

Age­related brainstem degeneration through microRNA modulation in mice.

Histopathological changes occur in the brainstem during the early stages of Alzheimer's disease (AD), with the pathological changes of the brain lesions ascending progressively in accordance with the Braak staging system. The senescence­accelerated mouse prone 8 (SAMP8) mouse model has been previously used as a model of age­dependent neurodegenerative diseases, including AD. In the present study, microRNAs (miRNAs) that were upregulated or downregulated in SAMP8 brainstems were identified using miRNA profiling of samples obtained from miRNA arrays. The preliminary stage of cognitive dysfunction was examined using male 5­month­old SAMP8 mice, with age­matched senescence­accelerated mouse resistant 1 mice as controls. A Y­maze alternation test was performed to assess short­term working memory and miRNA profiling was performed in each region of the dissected brain (brainstem, hippocampus and cerebral cortex). SAMP8 mice tended to be hyperactive, but short­term working memory was preserved. Two miRNAs were upregulated (miR­491­5p and miR­764­5p) and two were downregulated (miR­30e­3p and miR­323­3p) in SAMP8 brainstems. In SAMP8 mice, the expression level of upregulated miRNAs were the highest in the brainstem, wherein age­related brain degeneration occurs early. It was demonstrated that the order of specific miRNA expression levels corresponded to the progression order of age­related brain degeneration. Differentially expressed miRNAs regulate multiple processes, including neuronal cell death and neuron formation. Changes in miRNA expression may result in the induction of target proteins during the early stages of neurodegeneration in the brainstem. These findings suggest that studying altered miRNA expression may provide molecular evidence for early age­related neuropathological changes.

Effect of human urinary kallidinogenase on cognitive function of SAMP8 mouse model and its mechanism / 中国药理学通报

Aim To study the effect of human urinary kallidinogenase(HUK)on the cognitive function of SAMP8 mouse model and its mechanism. Methods SAMP8 mice were divided intofive groups:SAMP8 group,treatment group(giving 8.75×10-3,1.75×10-2,3.5×10-2,7.0×10-2 HUK),and the SAMR1 vehicle group was used as blank control. Each group was performed Morris water maze to detect spatial cognition. Afterwards the group with the most obvious cognitive improvement(HUK group)was selected for the follow-up experiments. Immunohistochemical detection of ChAT expression in CA3 area was further verified by RtPCR. Western blot was used to detect the expression of PSD95,SYN,BDNF,and pCREB protein. The activity of MPO and the content of IL-1β and IL-18 were determined. Results The passing times in the SAMP8 group was less than that of the SAMR1 group(P<0.05). The passing times of treatment group increased compared with the SAMP8 group(P<0.05 or P<0.01),and the spatial probe time of the target quadrant was shorter(P<0.05 or P<0.01). We conducted follow-up experiments with group d(HUK group). The expression of ChAT positive cells in CA3 area of SAMP8 group was significantly lower than that of SAMR1 group; the expression of positive cells in HUK group significantly increased; RtPCR showed that ChAT expression in SAMP8 group was lower than that in SAMR1 group,and ChAT expression was significantly higher than that in SAMP8 group after HUK treatment. Compared with the SAMR1 group,the levels of IL-1β,IL-18 and MPO activity in the CA3 area of SAMP8 group significantly increased,and the protein expressions of PSD95,SYN,BNDF and pCREB decreased. After HUK treatment,the content of IL-1β,IL-18 and MPO activity decreased,and the expression of PSD95,SYN,BNDF and pCREB increased. Conclusions HUK can improve the spatial cognition of SAMP8 mice. The mechanism may be achieved by promoting the expression of ChAT in CA3 area,reducing the oxidative stress and increasing synapse-related proteins.

Pharmacological inhibition of asparaginyl endopeptidase by δ-secretase inhibitor 11 mitigates Alzheimer's disease-related pathologies in a senescence-accelerated mouse model.

BACKGROUND: Currently, there is no cure for Alzheimer's disease (AD). Therapeutics that can modify the early stage of AD are urgently needed. Recent studies have shown that the pathogenesis of AD is closely regulated by an endo/lysosomal asparaginyl endopeptidase (AEP). Inhibition of AEP has been reported to prevent neural degeneration in transgenic mouse models of AD. However, more than 90% of AD cases are age-related sporadic AD rather than hereditary AD. The therapeutic efficacy of AEP inhibition in ageing-associated sporadic AD remains unknown. METHODS: The senescence-accelerated mouse prone 8 (SAMP8) was chosen as an approximate model of sporadic AD and treated with a selective AEP inhibitor,: δ-secretase inhibitor 11. Activation of AEP was determined by enzymatic activity assay. Concentration of soluble amyloid ß (Aß) in the brain was determined by ELISA. Morris water maze test was performed to assess the learning and memory-related cognitive ability. Pathological changes in the brain were explored by morphological and western blot analyses. RESULTS: The enzymatic activity of AEP in the SAMP8 mouse brain was significantly higher than that in the age-matched SAMR1 mice. The half maximal inhibitory concentration (IC50) for δ-secretase inhibitor 11 to inhibit AEP in vitro is was around 150 nM. Chronic treatment with δ-secretase inhibitor 11 markedly decreased the brain AEP activity, reduced the generation of Aß1-40/42 and ameliorated memory loss. The inhibition of AEP with this reagent not only reduced the AEP-cleaved tau fragments and tau hyperphosphorylation, but also attenuated neuroinflammation in the form of microglial activation. Moreover, treatment with δ-secretase inhibitor 11 prevented the synaptic loss and alleviated dendritic disruption in SAMP8 mouse brain. CONCLUSIONS: Pharmacological inhibition of AEP can intervene and prevent AD-like pathological progress in the model of sporadic AD. The up-regulated AEP in the brain could be a promising target for early treatment of AD. The δ-secretase inhibitor 11 can be used as a lead compound for translational development of AD treatment.

Dietary Intake of Green Nut Oil or DHA Ameliorates DHA Distribution in the Brain of a Mouse Model of Dementia Accompanied by Memory Recovery.

Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid, has significant healthbenefits. Previous studies reported decreased levels of DHA and DHA-containing phosphatidylcholines inthe brain of animals suffering from Alzheimer's disease, the most common type of dementia; furthermore,DHA supplementation has been found to improve brain DHA levels and memory efficiency in dementia. Oilextracted from the seeds of Plukenetia volubilis (green nut oil; GNO) is also expected to have DHA like effectsas it contains approximately 50% α-linolenic acid, a precursor of DHA. Despite this, changes in the spatialdistribution of DHA in the brain of animals with dementia following GNO or DHA supplementation remainunexplored. In this study, desorption electrospray ionization imaging mass spectrometry (DESI-IMS) wasapplied to observe the effects of GNO or DHA supplementation upon the distribution of DHA in the brain ofmale senescence-accelerated mouse-prone 8 (SAMP8) mice, a mouse model of dementia. DESI-IMS revealedthat brain DHA distribution increased 1.85-fold and 3.67-fold in GNO-fed and DHA-fed SAMP8 mice,respectively, compared to corn oil-fed SAMP8 mice. Memory efficiency in SAMP8 mice was also improvedby GNO or DHA supplementation. In summary, this study suggests the possibility of GNO or DHAsupplementation for the prevention of dementia.

The effects of dietary fatty acids on bone, hematopoietic marrow and marrow adipose tissue in a murine model of senile osteoporosis.

Purpose: Marrow adipose tissue (MAT) expansion and associated lipotoxicity are important drivers of age-related bone loss and hematopoietic bone marrow (HBM) atrophy. Fish oil and borage oil (rich in ω3 fatty acids) can partially prevent aged-related bone loss in SAMP8 mice. However, whether preservation of bone mass in this progeria model is associated with MAT volumes remains unknown.Results: MAT volume fraction (MAT%) showed a negative association with hematopoietic bone marrow (HBM%;r=-0.836, p<0.001) and bone (bone%;r=-0.344, p=0.013) volume fractions.Adjusting for multiple comparisons, bone% was higher and MAT% was lower in Fish oil (FO)-supplemented groups vs. controls (p<0.001). HBM% did not differ significantly between the four groups. However, in the group supplemented with FO, HBM comprised higher fractions and MAT constituted lower fractions of total marrow vs. controls (p<0.001).Conclusion: Feeding FO-enriched diet prevented age-related bone and HBM loss, by reducing MAT expansion. Our results further emphasize on the role(s) of MAT expansion in bone and HBM atrophy.Methods: SAMP8 mice (n>9 /group) were allocated into 4 categories and fed a control ration, FO-, sunflower oil (SFO)- and borage oil-enriched diets for lifetime. Femurs were scanned using microcomputed tomography (µCT) and bone, MAT, and HBM volumes were determined using an image analysis software.

Effects of chronic noise exposure on the microbiome-gut-brain axis in senescence-accelerated prone mice: implications for Alzheimer's disease.

BACKGROUND: Chronic noise exposure is associated with neuroinflammation and gut microbiota dysregulation and increases the risk of Alzheimer's disease (AD). Environmental hazards are also thought to be associated with genetic susceptibility factors that increase AD pathogenesis. However, there is limited experimental evidence regarding the link between chronic noise stress and microbiome-gut-brain axis alterations, which may be closely related to AD development. METHODS: The aim of the present study was to systematically investigate the effects of chronic noise exposure on the microbiome-gut-brain axis in the senescence-accelerated mouse prone 8 (SAMP8) strain. We established SAMP8 mouse models to examine the consequences of noise exposure on the microbiome-gut-brain axis. Hippocampal amyloid-ß (Aß) assessment and the Morris water maze were used to evaluate AD-like changes, 16S ribosomal RNA sequencing analyses were used for intestinal flora measurements, and assessment of endothelial tight junctions and serum neurotransmitter and inflammatory mediator levels, as well as fecal microbiota transplant, was conducted to explore the underlying pathological mechanisms. RESULTS: Chronic noise exposure led to cognitive impairment and Aß accumulation in young SAMP8 mice, similar to that observed in aging SAMP8 mice. Noise exposure was also associated with decreased gut microbiota diversity and compositional alterations. Axis-series studies showed that endothelial tight junction proteins were decreased in both the intestine and brain, whereas serum neurotransmitter and inflammatory mediator levels were elevated in young SAMP8 mice exposed to chronic noise, similar to the observations made in the aging group. The importance of intestinal bacteria in noise exposure-induced epithelial integrity impairment and Aß accumulation was further confirmed through microbiota transplantation experiments. Moreover, the effects of chronic noise were generally intensity-dependent. CONCLUSION: Chronic noise exposure altered the gut microbiota, accelerated age-related neurochemical and inflammatory dysregulation, and facilitated AD-like changes in the brain of SAMP8 mice.

Effect of electroacupuncture on Aβ and insulin degrading enzyme in the frontal cortex of senescence accelerated mouse/prone 8 / 中华行为医学与脑科学杂志

Objective To observe the effect of electroacupuncture at " Baihui"," Shenshu" and " Taixi" points on learning and memory,the expression of Aβ and insulin degrading enzyme(IDE) in the brain of SAMP8 mice.Methods Eight-month-old SAMR1 and SAMP8 mice were treated with electroacupuncture at " Baihui"," Shenshu" and "Taixi" points for eight consecutive weeks.The distribution and expression of Aβ and IDE in the brain prefrontal cortex of mouse were observed using immunohistochemistry and Western blot.Learning and memory function was assayed by Morris water maze(MWM).Results Compared with the normal control group,the brain prefrontal cortex of SAMP8 mice showed increased Aβ levels ((179.02± 15.11) ％),decreased IDE protein expression ((51.35 ± 14.94) ％).MWM showed the escape latency in SAMP8 mice was significantly longer than that in the control group (P＜0.05).Compared with the model group,Aβ levels in SAMP8 mice were markedly decreased in electroacupuncture group((119.72±9.21)％) and memantine-treated group ((116.84 ± 12.09) ％).IDE protein levels were increased by ((92.06 ± 8.05) ％) and ((83.84± 15.28) ％) after treatment with electroacupuncture and memantine relative to model group.MWM showed the escape latency was significantly shorter in SAMP8 mice treated with electroacupuncture and memantine than that in the model group(P＜0.05).Conclusion Electroacupuncture at " Baihui"," Shenshu" and "Taixi" points can inhibit Aβ levels,increase the expression of IDE and improve the learning and memory function of SAMP8 mice.

Design, synthesis and in vivo study of novel pyrrolidine-based 11ß-HSD1 inhibitors for age-related cognitive dysfunction.

Recent findings suggest that treatment with 11ß-HSD1 inhibitors provides a novel approach to deal with age-related cognitive dysfunctions, including Alzheimer's disease. In this work we report potent 11ß-HSD1 inhibitors featuring unexplored pyrrolidine-based polycyclic substituents. A selected candidate administered to 12-month-old SAMP8 mice for four weeks prevented memory deficits and displayed a neuroprotective action. This is the first time that 11ß-HSD1 inhibitors have been studied in this broadly-used mouse model of accelerated senescence and late-onset Alzheimer's disease.

Tongluo Xingnao Effervescent Tablets ameliorates cognitive function of SAMP8 mice via Nampt/SIRT1/FOXO3 pathway / 中成药

AIM To investigate the effects of Tongluo Xingnao Effervescent Tablets (Chuanxiong Rhizoma,Angelicae sinensis Radix and Scutellariae Radix) on the learning and memory function in SAMP8 mice,and improvements in cognitive function.METHODS Morris water maze was used to evaluate the change of cognitive function in SAMP8 mice after they were treated with Tongluo Xingnao Effervescent Tablets for 60 d,and the activity of superoxide dismutase (SOD),the concentration of protein carbonyls (PC),the ratio of NAD +/NADH in brain tissue were detected by ELISA,the expression of Nampt,SIRT1 and FOXO3 in hippocampus were measured with immunohistochemical methods.RESULTS Tongluo Xingnao Effervescent Tablets shortened escape latency and obviously increased percentage of time in target quadrant in hidden platform test and increased the times entering the target quadrant in spatial probe test in SAMP8 mice.It evidently enhanced the activity of SOD,the ratio of NAD +/NADH and distinctly decreased the protein carbonyls level.Moreover,Tongluo Xingnao Effervescent Tablets could markedly up-regulate the expression of Nampt and SIRT1,but evidently down-regulate FOXO3 protein expression.CONCLUSION The experimental data show that Tongluo Xingnao Effervescent Tablets can enhance the cognitive function of SAMP8 through regulating Nampt/SIRT1/FOXO3 signal pathway.

Antisense against Amyloid-ß Protein Precursor Reverses Memory Deficits and Alters Gene Expression in Neurotropic and Insulin-Signaling Pathways in SAMP8 Mice.

The senescence-accelerated mouse (SAMP8) strain exhibits an age-related decrease in memory accompanied by an increase in hippocampal amyloid-ß protein precursor (AßPP) and amyloid-ß peptide (Aß). We have shown that administration of an antisense oligonucleotide against the Aß region of AßPP (AßPP antisense) reverses the memory deficits. The purpose of this study was to determine the effect of peripheral (IV) administration of AßPP antisense on hippocampal gene expression. The AßPP antisense reversed the memory deficits and altered expression of 944 hippocampal genes. Pathway analysis showed significant gene expression changes in nine pathways. These include the MAPK signaling pathway (p = 0.0078) and the phosphatidylinositol signaling pathway (p = 0.043), which we have previously shown to be altered in SAMP8 mice. The changes in these pathways contributed to significant changes in the neurotropin (p = 0.0083) and insulin signaling (p = 0.015) pathways, which are known to be important in learning and memory. Changes in these pathways were accompanied by phosphorylation changes in the downstream target proteins p70S6K, GSK3ß, ERK, and CREB. These changes in hippocampal gene expression and protein phosphorylation may suggest specific new targets for antisense therapy aimed at improving memory.

The GLP-1 Receptor Agonist Liraglutide Improves Memory Function and Increases Hippocampal CA1 Neuronal Numbers in a Senescence-Accelerated Mouse Model of Alzheimer's Disease.

Recent studies indicate that glucagon-like peptide 1 (GLP-1) receptor agonists, currently used in the management of type 2 diabetes, exhibit neurotrophic and neuroprotective effects in amyloid-ß (Aß) toxicity models of Alzheimer's disease (AD). We investigated the potential pro-cognitive and neuroprotective effects of the once-daily GLP-1 receptor agonist liraglutide in senescence-accelerated mouse prone 8 (SAMP8) mice, a model of age-related sporadic AD not dominated by amyloid plaques. Six-month-old SAMP8 mice received liraglutide (100 or 500 µg/kg/day, s.c.) or vehicle once daily for 4 months. Vehicle-dosed age-matched 50% back-crossed as well as untreated young (4-month-old) SAMP8 mice were used as control groups for normal memory function. Vehicle-dosed 10-month-old SAMP8 mice showed significant learning and memory retention deficits in an active-avoidance T-maze, as compared to both control groups. Also, 10-month-old SAMP8 mice displayed no immunohistological signatures of amyloid-ß plaques or hyperphosphorylated tau, indicating the onset of cognitive deficits prior to deposition of amyloid plaques and neurofibrillary tangles in this AD model. Liraglutide significantly increased memory retention and total hippocampal CA1 pyramidal neuron numbers in SAMP8 mice, as compared to age-matched vehicle-dosed SAMP8 mice. In conclusion, liraglutide delayed or partially halted the progressive decline in memory function associated with hippocampal neuronal loss in a mouse model of pathological aging with characteristics of neurobehavioral and neuropathological impairments observed in early-stage sporadic AD.

Changes in nerve- and endothelium-mediated contractile tone of the corpus cavernosum in a mouse model of pre-mature ageing.

Erectile dysfunction (ED) is very prevalent in the older population, although the ageing-related mechanisms involved in the development of ED are poorly understood. We propose that age-induced differences in nerve- and endothelium-mediated smooth muscle contractility in the corpus cavernosum (CC) could be found between a senescent-accelerated mouse prone (SAMP8) and senescent-accelerated mouse resistant (SAMR1) strains. We analysed the changes in muscle tension induced by electrical field stimulation (EFS) or agonist addition 'in vitro', assessing nerve density (adrenergic, cholinergic and nitrergic), the expression of endothelial nitric oxide synthase (eNOS), cGMP accumulation and the distribution of interstitial cells (ICs) by immunofluorescence. We observed no change in both the nerve-dependent adrenergic excitatory contractility at physiological levels of stimulation and in the nitrergic inhibitory response in SAMP8 animals. Unlike cholinergic innervation, the density of adrenergic and nitrergic nerves increased in SAMP8 mice. In contrast, smooth muscle sensitivity to exogenous noradrenaline (NA) was slightly reduced, whereas cGMP accumulation in response to EFS and DEA/NO, and relaxations to DEA/NO and sildenafil, were not modified. No changes in the expression of eNOS and in the distribution of vimentin-positive ICs were detected in the aged animals. The ACh induced atropine-sensitive biphasic endothelium-dependent responses involved relaxation at low concentrations that turned into contractions at the highest doses. CC relaxation was mainly because of the production of NO together with some relaxant prostanoid, which did not change in SAMP8 animals. In contrast, the contractile component was considerably higher in the aged animals and it was completely inhibited by indomethacin. In conclusion, a clear imbalance towards enhanced production of contractile prostanoids from the endothelium may contribute to ED in the elderly. On the basis of these data, we propose the senescence-accelerated mouse model as a reliable tool to analyse the basic ageing mechanisms of the CC.

SAMP8 mice have altered hippocampal gene expression in long term potentiation, phosphatidylinositol signaling, and endocytosis pathways.

The senescence-accelerated mouse (SAMP8) strain exhibits decreased learning and memory and increased amyloid beta (Aß) peptide accumulation at 12 months. To detect differences in gene expression in SAMP8 mice, we used a control mouse that was a 50% cross between SAMP8 and CD-1 mice and which showed no memory deficits (50% SAMs). We then compared gene expression in the hippocampus of 4- and 12-month-old SAMP8 and control mice using Affymetrix gene arrays. At 12 months, but not at 4 months, pathway analysis revealed significant differences in the long term potentiation (6 genes), phosphatidylinositol signaling (6 genes), and endocytosis (10 genes) pathways. The changes in long term potentiation included mitogen-activated protein kinase (MAPK) signaling (N-ras, cAMP responsive element binding protein [CREB], protein phosphatase inhibitor 1) and Ca-dependent signaling (inositol triphosphate [ITP] receptors 1 and 2 and phospholipase C). Changes in phosphatidylinositol signaling genes suggested altered signaling through phosphatidylinositol-3-kinase, and Western blotting revealed phosphorylation changes in serine/threonine protein kinase AKT and 70S6K. Changes in the endocytosis pathway involved genes related to clathrin-mediated endocytosis (dynamin and clathrin). Endocytosis is required for receptor recycling, is involved in Aß metabolism, and is regulated by phosphatidylinositol signaling. In summary, these studies demonstrate altered gene expression in 3 SAMP8 hippocampal pathways associated with memory formation and consolidation. These pathways might provide new therapeutic targets in addition to targeting Aß metabolism itself.

Changes in nerve-mediated contractility of the lower urinary tract in a mouse model of premature ageing.

BACKGROUND AND PURPOSE: A high incidence of lower urinary tract disorders is associated with ageing. In the senescent-accelerated prone (SAMP8) mouse strain and the senescent-accelerated resistant (SAMR1) strain, we compared smooth muscle contractility in responses to intrinsic neurotransmitters, both in the bladder and urethra. EXPERIMENTAL APPROACH: We analysed micturition frequency, the changes in muscle tension induced by electrical field stimulation or agonist administration, the density of nerves (adrenergic, cholinergic and nitrergic) and interstitial cells (ICs), as well as cGMP accumulation in bladder and urethral preparations. KEY RESULTS: Senescent mice of the SAMP8 strain displayed increased micturition frequency and excitatory contractility of neurogenic origin in the bladder. While cholinergic nerve density remained unchanged, there was a mild sensitization to ACh in male mice. Potentiation in the detrusor may be also provoked by the stronger contribution of ATP, together with reduced adrenergic innervation in males and COX-derived prostanoid production in females. The greater excitatory contractility in the urethra was probably due to the sensitization to noradrenaline, in conjunction with attenuated nitrergic relaxation. There were also fewer neuronal NOS immunoreactive (ir) nerves and vimentin-positive ICs, although the sildenafil- and diethylamine-NONOate-induced relaxations and cGMP-ir remained unchanged. CONCLUSIONS AND IMPLICATIONS: Premature senescent mice exhibit bladder and urethral hyperexcitability, coupled with reduced urethral relaxation of neurogenic origin, which could model the impaired urinary function in elderly humans. We propose that senescence-accelerated mice provide a useful tool to analyse the basic mechanisms of age-related changes in bladder and urethral function.

Memantine combined with environmental enrichment improves spatial memory and alleviates Alzheimer's disease-like pathology in senescence-accelerated prone-8 (SAMP8) mice.

Memantine is a N-methyl-D-aspartate (NMDA) receptor antagonist approved for the treatment of moderate to severe Alzheimer's disease (AD). Environmental enrichment (EE) has shown significant beneficial effects on functional improvement in AD. In this study, we sought to determine whether combining these two distinct therapies would yield greater benefit than either drug used alone. We investigated the effect of memantine combined with EE on spatial learning and memory and AD-like pathology in a widely used AD model, the senescence-accelerated prone mice (SAMP8). The SAMP8 mice were randomly assigned to enriched housing (EH) or standard housing (SH), where either memantine (20 mg/kg) or saline was given by gastric lavage once daily continuously for eight weeks. Our results showed that, when provided separately, memantine and EE significantly improved spatial learning and memory by shortening escape latencies and increasing the frequency of entrance into the target quadrant. When combined, memantine and EE showed additive effect on learning and memory as evidenced by significant shorter escape latencies and higher frequency of target entrance than either drug alone. Consistent with the behavior results, pathological studies showed that both memantine and EE significantly reduced hippocampal CA1 neurofibrilliary tangles (NFTs) as well as amyloid beta precursor protein (APP) levels. Combining both therapies synergistically lessened NFTs and APP expression compared to either drug alone in SAMP8 mice, indicating that the combination of memantine with EE could offer a novel and efficient therapeutic strategy for the treatment of AD.

EFFECTS OF ANDROGEN ON LEARNING AND MEMORY ABILITY AND HIPPOCAMPUS NEURONS IN SAMP8 MOUSE / 解剖学报

Objective To explore the effect of androgen on learning and memory ability and neurons in hippocampal CA1 region in senescence accelerated mouse prone strain/8(SAMP8).Methods Thirty 7-month-old male SAMP8 were randomly divided into sham-operation control group,castrated group and androgen replacement therapy after castration group.The dose of testosterone undecanoate(TU) was 37.4mg/(kg?15d).The capability of learning and memory was observed 45 days later through the Morris water maze(MWM) test and the change of neurons in hippocampal CA1 region was detected and analyzed by HE staining,immunohistochemal method and computer pathological image analysis system.Results 1.In the MWM test,the escape latency of castrated group were significantly prolonged(P0.05).2.With HE staining,neurons in hippocampal CA1 region of castrated group were found with diffused vacuolar degeneration,and sparse and disordered cellular arranpement.The cell nucleuses were karyochrome and karyopycnosis.The number and optical density of A? immune positive neurons were markedly higher than those of other groups(P