Changes of Learning and Memory Ability in fos-GFP Transgenic Mice

To study the effects of chronic intermittent hypoxia (CIH) on learning and memory ability in Sprague–Dawley rats, we established a rat model of CIH. A total of 24 male Sprague–Dawley rats were included and were assigned to three experimental groups (n = 8/group): the unhandled control (UC) group (normal feeding for 4 weeks), the CIH group (CIH for 4 weeks), and the removal of hypoxia (RH) group (normal feeding for 4 weeks after CIH for 4 weeks). All the results were analyzed using one-way ANOVA and comparison between groups was performed using S–N–K method. Performance on the Morris water maze test (a learning and memory test) was significantly worse for CIH rats than for UC rats and RH rats (P < 0.05), but was significantly better for RH rats than for UC rats (P < 0.05). Synaptophysin expression in the CA3 region of the hippocampus was reduced in the CIH group and the RH group compared with the UC group (P < 0.05), but was significantly greater in the RH group than in the CIH group (P < 0.05). Synaptophysin is a calcium-binding protein located in the membranes of presynaptic vesicles. Changes of synaptophysin expression may indirectly reflect the structural changes in the hippocampal CA3 region. In rats, CIH can cause declines in learning ability and memory and reduce the expression of synaptophysin in the CA3 region of the hippocampus; these effects could be partially rescued by the removal of hypoxic factors. The observed decline in learning and memory ability in rats may relate to a decrease in synapse quantity and structural changes in the CA3 region of the hippocampus.

To explore the relationship between alterations of neural network plasticity and spatial learning and memory functions in mouse models with depression-like behaviors. C57Thy1-YFP/GAD67-GFP mice were randomized into control group (with no treatment) and chronic unpredictable mild stress (CUMS) group (n=15) subjected to CUMS for 8 weeks. Depression-like behaviors of the mice were assessed using sucrose preference test, open field test, and forced swimming test, and their spatial learning and memory abilities were evaluated using Morris water maze test. The changes in the firing patterns of different neuronal subtypes were detected in the central nucleus of the amygdala (CeA) and the prelimbic cortex (PrL) using whole-cell patch-clamp technique. Compared with the control mice, CUMS mice showed significantly decreased sucrose preference, total distance moved, number of grid-crossings, entries into the central area, and time spent in the central area in the open field test (P < 0.01). In the forced swimming test, CUMS mice exhibited obviously shortened time of struggling, swimming, and climbing with increased immobility time. In Morris water maze test, CUMS mice showed significantly increased escape latency and path length, decreased percentage of distance and swimming time within the target quadrant, and increased first entry latency into the target zone and swimming time within the opposite quadrant. Exposure to CUMS resulted in significantly enhanced energy barrier and increased absolute refractory period and inter-spike interval of glutamatergic neurons in the CeA and GABAergic neurons in the PrL, while the opposite changes were observed in GABAergic neurons in the CeA and glutamatergic neurons in the PrL. CUMS-induced depression may lead to plastic changes in the excitatory and inhibitory neuronal networks within the CeA and PrL to cause impairment of spatial learning and memory abilities in mice.

Objective To observe effect of environmental enrichment on the learning and memory ability and the expressions of hypoxia inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) in rats with chronic cerebral hypoperfusion. Methods A total of 40 rats were randomly divided into 3 groups: bilateral vascular occlusion (2VO) of the common carotid arteries group (n=14, 2VO group), 2VO + enriched environment (EE) group (n=14, 2VO+ EE group) and sham group (n=12, SHAM group). Morris water maze, novel object recognition test, real-time reverse transcription-polymerase chain reaction (real-time RT-PCR), immunohistochemistry methods and Western blotting were used to detect changes in learning and memory ability of rats and HIF-1α and VEGF expression levels in hippocampus. Results Morris water maze showed that the escape latency was longer in the 2VO group than in the SHAM group at 3, 4 and 5 day during the training (all P<0.05), while the 2VO+ EE group spent significantly less time in finding the platform as compared with the 2VO group at 4 and 5 day (both P<0.05). The time for space exploration in target quadrant was less in 2VO group than in SHAM group (P<0.05), while it was longer in 2VO+ EE group than in 2VO group (P<0.05). Novel object recognition test showed that the 2VO operation impaired the priority index (PI) of time spending at exploring the novel object (P<0.05), and environmental enrichment could improve the PI in 2VO group (P<0.05). The real-time RT-PCR and Western blotting showed that the HIF-1α mRNA expression was higher in 2VO group than in SHAM group (P<0.05). The VEGF mRNA and protein expressions were higher in 2VO+ EE group than in 2VO group (both P<0.05). The expression of HIF-1α in hippocampal CA1 area was higher in 2VO group than in SHAM group (P<0.05). Conclusions Environmental enrichment can alleviate the damages of spatial and non-spatial learning and memory ability which are caused by chronic cerebral hypoperfusion. And HIF-1α and its downstream gene VEGF may be involved in the restoration of cognitive function by enriched environment. Key words: Brain ischemia; Cognition; Milieu therapy; Hypoxia-inducible factor 1; Vascular endothelial growth factor

Dopamine D1 receptor agonist treatment alleviates morphine-exposure-induced learning and memory impairments

Effects of Chinese herbal medicine Yinsiwei compound on spatial learning and memory ability and the ultrastructure of hippocampal neurons in a rat model of sporadic Alzheimer disease

Dulaglutide ameliorates STZ induced AD-like impairment of learning and memory ability by modulating hyperphosphorylation of tau and NFs through GSK3β

Alzheimer's disease (AD) is a typical neurodegenerative disease with a complex etiology. Until now, there has been no effective treatment available for AD; however, improving energy dysmetabolism, the key pathological event in the early stage of AD, can effectively delay the progression of AD. This paper aims to investigate the therapeutic effect and potential mechanism of the new Tiaoxin recipe on early AD. APP/PS1 mice were divided into a model group, a new Tiaoxin recipe group, and a donepezil group, and C57/BL mice were used for the control group. Mouse cognitive and learning abilities were tested using the Morris water maze test and a new object-recognition experiment. The 42 amino acid form of amyloid β peptide (Aβ1-42) content was detected by enzyme-linked immunosorbent assay, the senile plaque area was detected by thioflavin S staining, and the senescence- associated β-galactosidase (SA-β-gal)-positive area was detected by chemical staining. Also, the adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD+), and nicotinamide adenine dinucleotide hydride (NADH) contents were detected using a biochemical method, and the cluster of differentiation 38 (CD38) and silent mating-type information regulation 2 homolog 3 (SIRT3) protein expression levels were detected by immunofluorescence and Western blot analysis. Compared with those of the control group, the learning and memory abilities of the model group were impaired; the senile plaque deposition, Aβ1-42 content, and SA-βgal-positive staining area were increased; the ATP concentration, NAD+ concentration, and NAD+/NADH ratio were decreased; the CD38 protein expression level was increased; and the SIRT3 protein expression level was decreased. Following intervention with the new Tiaoxin recipe, the learning and memory abilities were improved; the senile plaque deposition, Aβ1-42 content, and SA-βgal-positive area were reduced; the ATP concentration, NAD+ concentration, and NAD+/NADH ratio were increased; CD38 protein expression was decreased, and SIRT3 protein expression was increased. This study shows that the new Tiaoxin Recipe can improve cognitive ability and reduce the Aβ1-42 content and senile plaque deposition in APP/PS1 mice, which may occur through the downregulation of CD38 protein expression, upregulation of SIRT3 protein expression, restoration of the NAD+ level, promotion of ATP synthesis, mitigation of energy metabolism disorders.

By 3 to 4 months of age, infants born full-term and without known disease display associative learning and memory abilities in the mobile paradigm, where an infant's leg is tethered to a mobile such that leg kicks result in proportional mobile movement. The first purpose of this study was to examine the learning and memory abilities of a group of infants born full-term compared with those of a comparison group. Little is known about the learning and memory abilities in infants born preterm, a group at known risk for future impairments in learning and movement. The second purpose of this study was to determine if and when an age-adjusted group of infants born prematurely display associative learning and memory abilities over a 6-week period. Ten infants born full-term (38-42 weeks gestational age [GA]) and 10 infants born preterm (<33 weeks GA and <2,500 g) who were tethered and had control over the mobile movement were independently compared with a comparison group of 10 infants born full-term who were tethered and viewed a moving mobile but did not have control over the mobile movement. Infants in all 3 groups were seen at 3 to 4 months of age and were excluded from participation for any known visual or orthopedic diagnoses. Infants were tested using the mobile conjugate reinforcement paradigm, where one leg is tethered to an overhead mobile such that kicking with that leg results in proportional mobile movement. The kicking rates of the full-term group and the preterm group were compared with their own initial (baseline) kicking rates and with those of the comparison group. After exposure to the conjugate relationship between kicking and mobile movement, the full-term group kicked more frequently compared with their own baseline levels and compared with the comparison group, fulfilling both criteria for learning and memory. In contrast, the preterm group did not increase their kicking rate according to both criteria. These results suggest that infants born prematurely differ in their performance in the mobile paradigm as compared with age-matched infants born full-term. The mobile paradigm may provide clinicians with an important early assessment of infants' associative learning and memory abilities. Follow-up studies are needed, however, to further validate this paradigm as a clinical assessment tool.

Objective To study the prevention effects of AduoLa Fuzhenglin(ADL)Oll the brain injury induced by microwave radiation in rats.Methods A total of 140 male Wismr rats were divided randomly into 5 groups,including control group,microwave exposed group,low dosage(0.75 g·kg-1·d-1)group.middle dosage(1.5 g·kg-1·d-1)group and high dosage(3 g·kg-1·d-1)group.Rats in three ADL groups were lavaged with ADL per day for 2 weeks before radiation.After administration,rats were exposed to microwave at 30 mW/cm2 for 15 min.The abilities of learning and memory were detected by Morris water maze,and the contents of amino acids neurotransmitter of hippocampus were detected by HPLC, then the histology and uhrastrncture of hippocampus were observed with light and electron microscope at 6 h,7 and 14 d after exposure.Results The abilities of learning and memory were declined(F=0.000-0.043,P<0.05)from 6 h to 7 d after exposure,and the contents of four kinds of amino acid neurotransmitter in hippocampus were decreased,of which GLU,GLY and GABA were decreased significantly(F=0.000-0.007,P<0.01)at 6h after exposure,then tissue edema,neuronal degeneration,neuron mitoehondria swelling and cavitation,endocytoplasmie rotieulum broaden,synaptic cleft blurred,and perivascular space widen were found in the hippocampus at 6 h and 7 d after exposure.The changes in low dosage group were similar to those of the radiation group.However,in middle and high dosage groups,the abilities of learning and memory were normal to some extent with the significant differences compared to the radiation group from 6 h to 7 d after exposure(F=0.015-0.028.P<0.05).The contents of four kinds of amino acid neurotransmitter were not decreased,especially GLU contents close tO normal level.There were significant differences between middle and high dosage groups and radiation group at 6 h after exposure(F=0.000-0.042,P<0.05).Moreover,no obvious injury in the hippocampus was observed in middle and high dosage groups at 6 h and 7 d after exposure.Conclusions Exposure to 30 mW/cm2 microwave radiation could decrease the abilities of learning and memory,induce amino acid neurotransmitter turbulence,and injure the histology and uhrastructure of hippocampus.ADL at the dosages of 1.5 and 3 g·kg-1·d-1 would have preventive effects on the injury induced by microwave exposure.The concentration of 1.5 g·kg-1 ·d-1 of ADL might be the effective dosage to prevent the brain damage after microwave exposure. Key words: AduoLa Fuzhenglin; Microwave; Rat; Brain injury; Prevention

Objective To analyze the expression of glial fibrillary acidic protein(GFAP) in hippocampal of rats with hypoxic-ischemic brain damage(HIBD) after injection of bone marrow stromal cells(BMSCs) supernatant into the lateral ventricle of the neonate rats, assess the ability of learning and memory, and explore the mechanism. Methods 7-day-old SD rats were randomly divided into sham operation group, model group, cells and supernatant group, with 20 rats in each group. The HIBD model was established via the ligation of left carotid arteries followed by 2-hour hypoxia. One week later, rats in control group were injected with 0.01 mol/L PBS 2 μl via the left ventricle. Meanwhile, the cell and the supernatant groups were injected with BMSCs and supernatant harvested from BMSC culture, respectively, via the same route.In the sham operation group, the left carotid arteries were separated but not ligated, and no hypoxia treatment was imposed on this group. They also received 0.01 mol/L PBS injection 2 μl per weak post surgery. 8 weeks later, Morris water maze test was performed to assess the learning and memory, and the expression of GFAP in the dentate gyrus of rats was measured by immunohistochemistry. Results Morris water maze showed that the searching time of the probe trail(T1: (15.40±2.80) s) and reversal probe trail(T2: (16.45±1.16) s )of the model group was shorter than that of the sham operation group(T1: (19.96±2.57)s, T2: (2: 25.32±2.54)s, P 0.05). The integral optical density(IOD) value of GFAP positive cells was higher in the model group than that in the sham operation group(15.26±1.49 vs 12.82±2.56, P 0.05). Conclusion BMSC supernatant injected through lateral ventricle can improve the HIBD rats' abilities of learning and memory. The mechanism might be that MSCs secrete some cytokines to promote central nervous system repair. Key words: Bone marrow mesenchymal stem cells; Supernatant; Hypoxic ischemic brain damage; Glial fibrillary acidic protein; Memory

Ketamine, a common anesthetic used for pediatric patients, has been shown to induce neurotoxicity and alter adolescent behaviors in rats when administered during neonatal period. However, the mechanisms underlying this kind of neurotoxicity remain largely to be determined. Herein, we studied whether the reactive oxygen species (ROS) due to the increased NOX2 mediates loss of phenotype of PV interneurons and thus contributes to long-term cognitive impairments after repeated ketamine exposures. Sprague-Dawley male rat pups received a daily administration of ketamine intraperitoneally (75mg/kg) from postnatal day 6 (P6) to P8 for three consecutive days. For the interventional study, pups were treated with a NADPH oxidase inhibitor, apocynin (Apo). Learning and memory abilities were tested by the open field, fear conditioning, and Morris water maze on P40, P42-44, and P50-56, respectively. For histological and biochemical assays, a separate cohort of rats was killed on P9 or P60, and the brain tissues were harvested. Our results showed the upregulation of 8-OHdG and gp91/NOX2 and downregulation of PV and glutamic acid decarboxylase 67 (GAD67) after repeated ketamine exposures, which co-occurred with the long-term cognitive impairments as evidenced by the decreased freezing time to context. However, Apo treatment attenuated these abnormalities. Our results suggest that oxidative damage, probably due to the increased NOX2, mediates loss of phenotype of PV interneurons and thus contributes to long-term cognitive impairments after repeated ketamine exposures. Moreover, the inhibition of NADPH oxidase may protect against cognitive dysfunction.

Increased Anxiety-like Behaviors in Adgra1−/− Male But Not Female Mice are Attributable to Elevated Neuron Dendrite Density, Upregulated PSD95 Expression, and Abnormal Activation of the PI3K/AKT/GSK-3β and MEK/ERK Pathways

Objective To evaluate the effects of ganglioside GM1 on hypoxic ischemic brain damage (HIBD) in neonatal rats and on the expression of potassium-chloride cotransporter 2 (KCC2) in hippocampus. Methods Seven-day-old Sprague-Dawley (SD) rats (n=72) were randomly divided into a sham group, an HIBD group and a ganglioside GM1 group. Each group was further divided into a 3 d subgroup and a 21 d subgroup according to the different detection index (n=12). Rat HIBD models were prepared according the Rice-Vannucci method. After HIBD, the ganglioside GM1 group was given ganglioside GM1 20 mg/(kg·d) by intraperitoneal injection for 3 d continuously. 2-, 3-, 5-triphenyltetrazolium chloride (TTC) was preformed to evaluate the area of cerebral infarction of HIBD in each 3 d subgroup. Spontaneous activity recorder was used to observe the locomotor activity of the rats in the 21 d subgroups. Morris water maze test was conducted for assessment of rats' learning and memory abilities in the 21 d subgroups. Western blot analysis was employed to determine the alterations in KCC2 expression in hippocampus in all the 3 d and 21 d subgroups. Results Compared with the HIBD group (28.6%±5.2%), the ratio of cerebral infarction volume in the ganglioside GM1 group (11.3%±2.4%) was significantly reduced (P<0.05). Compared with the HIBD group (289.6±61.3), the number of locomotor activities within 2 h in the ganglioside GM1 group (412.1±66.8) was significantly increased (P<0.05). Compared with the HIBD group, the escape latency was significantly reduced, but the percentage time of target quadrant and the number of crossing the platform were significantly increased in the ganglioside GM1 group (P<0.05). Three days and 21 days after HIBD, the expression of KCC2 in the ganglioside GM1 group was significantly higher than that in the HIBD group (P<0.05). Conclusion Ganglioside GM1 may have a significant protective effect on HIBD in neonatal rats, and its mechanism may be related to regulation of the expression of KCC2 in hippocampus. Key words: Ganglioside GM1; Hypoxic ischemic brain damage; Potassium-chloride cotransporter 2

Oysters (Crassostrea talienwhanensis) contain large amounts of protein and exhibit many biological activities. This study was aimed at preparing oyster protein hydrolysates (OPH) and evaluating the OPH based on a spatial learning and memory capacity. A response surface methodology was employed to optimize hydrolysis conditions to determine the OPH with the highest AChE inhibitory activity, and the optimum extraction conditions were as follows: enzyme concentration of 1444.88 U g−1, pH of 7.38, extraction temperature of 45 °C, extraction time of 5.56 h and a water/material ratio of 2.45 : 1, and the minimum acetylcholinesterase (AChE) activity was 0.069 mM min−1. The spatial memory and learning abilities and passive avoidance in mice were determined by using the Morris water maze test and a dark/light avoidance test. Furthermore, the OPH group could relieve oxidative stress, reduce AChE levels, increase choline acetyltransferase (ChAT) levels and alleviate inflammatory reaction through reduction of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. Additionally, up-regulated expressions of brain-derived neurotrophic factor (BDNF) and neural cell adhesion molecules (NCAM) were observed in mice treated with OPH. These findings suggested that OPH could be a functional food candidate to improve the learning and memory ability associated with oxidative stress and inflammatory reactions.

The effects of sodium overload on learning and memory parameters of model animals are disputable. Additionally, it has been proved that brain oxidative stress leads to disrupted cognitive abilities. The aim of our study was to estimate the learning abilities and the oxidative status of brain cortices of rats in a model of sodium overload. In our experimental part two groups of male Wistar albino rats, receiving standard rodent food, were used – a Control group (C) and a NaCl group (NaCl), receiving 2.5 g/kg NaCl, p.o. once daily, for one week. After developing the sodium overload model, both groups were tested for their 8-Arm Radial Maze (8-ARM) performance. All rat brain cortices were tested for activity of Xanthine oxidase and free radical accumulation, using spectrophotometric methods. The results for group NaCl were presented as percentages of the corresponding biomarkers for group C. Group C showed much less anxiety and unmotivated behavior and considerably better memory and learning abilities than group NaCl. Much higher levels of xanthine oxidase and free radical accumulation were registered in the brain cortices of group NaCl compared to the brain cortices of group C. We discuss that the sodium overload resulted in oxidative stress in the rat brain cortex, mainly due to accumulation of superoxide. This was accompanied with increased anxiety, unmotivated choices, and disrupted learning and memory abilities. We concluded that excessive dietary NaCl intake in a rat model of sodium overload is accompanied by disrupted learning and memory abilities, increased anxiety and increased oxidative stress in the brain cortex.