Effects of early-life zinc deficiency on learning and memory in offspring and the changes in DNA methylation patterns.

OBJECTIVE: To investigate the effect of maternal zinc deficiency on learning and memory in offspring and the changes in DNA methylation patterns. METHODS: Pregnant rats were divided into zinc adequate (ZA), zinc deficient (ZD), and paired fed (PF) groups. Serum zinc contents and AKP activity in mother rats and offspring at P21 (end of lactation) and P60 (weaned, adult) were detected. Cognitive ability of offspring at P21 and P60 were determined by Morris water maze. The expression of proteins including DNMT3a, DNMT1, GADD45ß, MeCP2 and BDNF in the offspring hippocampus were detected by Western-blot. The methylation status of BDNF promoter region in hippocampus of offspring rats was detected by MS-qPCR. RESULTS: Compared with the ZA and PF groups, pups in the ZD group had lower zinc levels and AKP activity in the serum, spent more time finding the platform and spent less time going through the platform area. Protein expression of DNMT1 and GADD45b were downregulated in the ZD group during P0 and P21 but not P60 compared with the ZA and PF group, these results were consistent with a reduction in BDNF protein at P0 (neonate), P21. However, when pups of rats in the ZD group were supplemented with zinc ion from P21 to P60, MeCP2 and GADD45b expression were significantly downregulated compared with the ZA and PF group. CONCLUSION: Post-weaning zinc supplementation may improve cognitive impairment induced by early life zinc deficiency, whereas it may not completely reverse the abnormal expression of particular genes that are involved in DNA methylation, binding to methylated DNA and neurogenesis.

Changes of hippocampus proteomic profiles after blueberry extracts supplementation in APP/PS1 transgenic mice.

Objective: To examine protein changes in the hippocampus of APP/PS1 transgenic mice after blueberry extracts (BB) intervention.Methods: Eight APP/PS1 transgenic mice were randomly assigned to Alzheimer's disease (AD)+BB group (n=4) and AD+control group (n=4). After a 16-week treatment, 2-DE and MALDI-TOF-MS were used to compare the proteomic profiles of the hippocampus in the two groups and Western blot was used to confirm the important differentially expressed proteins.Results: Twelve proteins were differentially expressed between the two groups. Nine of them were identified. Cytochrome b-c1 complex subunit 6, beta-actin, dynamin 1, and heat shock cognate 71 were up-regulated in AD+BB group, while a-enolase, stress-induced-phosphoprotein 1, malate dehydrogenase (MDH), MDH 1, and T-complex protein 1 subunit beta were down-regulated, respectively. Importantly, some of the identified proteins (e.g. dynamin 1) are known to be involved in cognitive impairment. Western blot analysis of hippocampus dynamin 1 expression confirmed the proteomic findings.Conclusions: The consumption of BB modulates the expression of proteins that are linked to the improvements of cognitive dysfunction in hippocampus of APP/PS1 transgenic mice.

Zn2+ reduction induces neuronal death with changes in voltage-gated potassium and sodium channel currents.

In the present study, cultured rat primary neurons were exposed to a medium containing N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a specific cell membrane-permeant Zn2+ chelator, to establish a model of free Zn2+ deficiency in neurons. The effects of TPEN-mediated free Zn2+ ion reduction on neuronal viability and on the performance of voltage-gated sodium channels (VGSCs) and potassium channels (Kvs) were assessed. Free Zn2+ deficiency 1) markedly reduced the neuronal survival rate, 2) reduced the peak amplitude of INa, 3) shifted the INa activation curve towards depolarization, 4) modulated the sensitivity of sodium channel voltage-dependent inactivation to a depolarization voltage, and 5) increased the time course of recovery from sodium channel inactivation. In addition, free Zn2+ deficiency by TPEN notably enhanced the peak amplitude of transient outward K+ currents (IA) and delayed rectifier K+ currents (IK), as well as caused hyperpolarization and depolarization directional shifts in their steady-state activation curves, respectively. Zn2+ supplementation reversed the effects induced by TPEN. Our results indicate that free Zn2+ deficiency causes neuronal damage and alters the dynamic characteristics of VGSC and Kv currents. Thus, neuronal injury caused by free Zn2+ deficiency may correlate with its modulation of the electrophysiological properties of VGSCs and Kvs.

Cyanidin-3-O-galactoside and blueberry extracts supplementation improves spatial memory and regulates hippocampal ERK expression in senescence-accelerated mice.

OBJECTIVE: To investigate whether the antioxidation and the regulation on the Extracellular Regulated Protein Kinases (ERK) signaling pathway are involved in the protective effects of blueberry on central nervous system. METHODS: 30 Senescence-accelerated mice prone 8 (SAMP8) mice were divided into three groups and treated with normal diet, blueberry extracts (200 mg/kg•bw/day) and cyaniding-3-O-galactoside (Cy-3-GAL) (50 mg/kg•bw/day) from blueberry for 8 weeks. 10 SAMR1 mice were set as control group. The capacity of spatial memory was assessed by Passive avoidance task and Morris water maze. Histological analyses on hippocampus were completed. Malondialdehyde (MDA) levels, Superoxide Dismutase (SOD) activity and the expression of ERK were detected. RESULTS: Both Cy-3-GAL and blueberry extracts were shown effective functions to relieve cellular injury, improve hippocampal neurons survival and inhibit the pyramidal cell layer damage. Cy-3-GAL and blueberry extracts also increased SOD activity and reduced MDA content in brain tissues and plasma, and increased hippocampal phosphorylated ERK (p-ERK) expression in SAMP8 mice. Further more, the passive avoidance task test showed that both the latency time and the number of errors were improved by Cy-3-GAL treatment, and the Morris Water Maze test showed significant decreases of latency were detected by Cy-3-GAL and blueberry extracts treatment on day 4. CONCLUSION: Blueberry extracts may reverse the declines of cognitive and behavioral function in the ageing process through several pathways, including enhancing the capacity of antioxidation, altering stress signaling. Cy-3-GAL may be an important active ingredient for these biological effects.

[Cytoprotective effect of blueberry extracts against oxidative damage of rat hippocampal neurons induced by H2O2].

OBJECTIVE: To investigate the protective effect of blueberry extract (BE, 25% anthocyanins) against oxidative damage in primary cultures of rat hippocampal neurons induced by H2O2. METHODS: Rat hippocampal neurons were randomly assigned to control group, H2O2 group and BE pretreatment groups, BE at six different doses (0.01, 0.1, 1.0, 10.0, 20.0 and 40 microg/ml) and then exposed to 50 micromol/L H2O2 for twenty-four hours. To selecte the most fittest concentration of BE by testing viability of neurons and activity of LDH. Then MDA concentration, SOD activity and neuronal apoptosis were(checked) measured. RESULTS: (1) Compared with H2O2 group, the hippocampal cell viabilities in the 0.1, 1.0 and 10 microg/ml BE groups were significantly increased from 57.44% to 78.42%, 87.71% and 72.40% separately. The activity of LDH in BE groups at varied concentrations (0.1, 1.0 and 10 microg/ml) was significiantly lower than that in H2O2 group. It was found that 1 microg/ml BE had the furthest protective effect against oxidative damage in primary cultures of rat hippocampal neurons induced by H2O2. (2) The concentration of MDA and the rate of neuronal apoptosis of BE group (1 microg/ml) were much lower than H2O2 group, while SOD activity was much higher. CONCLUSION: Proper dose of BE has remarkable protective effect against oxidative stress in primary cultures of rat hippocampal neurons induced by H2O2, the mechanism may be related to decreasing the neuronal apoptosis and enhancing the antioxidation of hippocampal neurons.