Melatonin improves memory defects in a mouse model of multiple sclerosis by up-regulating cAMP-response element-binding protein and synapse-associated proteins in the prefrontal cortex.

Multiple sclerosis is a progressive autoimmune disorder of the myelin sheath and is the most common inflammatory disease of young adults. Up to 65% of multiple sclerosis patients have cognitive impairments such as memory loss and difficulty in understanding and maintaining attention and concentration. Many pharmacological interventions have been used to reverse motor impairments in multiple sclerosis patients; however, none of these drugs improve cognitive function. Melatonin can diffuse through the blood-brain barrier and has well-known antioxidant and anti-inflammatory properties with almost no side effects; it is, therefore, a promising neuroprotective supplement for many neurological diseases, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, ischemic stroke, and fibromyalgia. However, only some researches have assessed the effect of melatonin on cognitive dysfunction in multiple sclerosis. Here, we evaluated the effects of melatonin supplementation on memory defects induced by cuprizone in a mouse model of multiple sclerosis. Cuprizone (400 mg/kg) and melatonin (80 mg/kg) were administered to SWR/J mice daily for 5 weeks. Open field, tail-flick, and novel object recognition behavioral tests were performed. Also, expression of cAMP-response element-binding protein, synaptophysin, and postsynaptic density protein 95 were measured in the prefrontal cortex. Melatonin significantly improved the memory defects induced by cuprizone toxicity by up-regulating cAMP-response element-binding protein and by increasing expression of the synapse-associated synaptophysin and postsynaptic density protein 95 genes in the prefrontal cortex. These results indicate that melatonin may provide protective effects against memory impairments associated with multiple sclerosis.

Maternal Folic Acid Supplementation During Pregnancy Promotes Neurogenesis and Synaptogenesis in Neonatal Rat Offspring.

Maternal folic acid supplementation during pregnancy is associated with improved cognitive performances in offspring. However, the effect of supplementation on offspring's neurogenesis and synaptogenesis is unknown, and whether supplementation should be continued throughout pregnancy is controversial. In present study, 3 groups of female rats were fed a folate-normal diet, folate-deficient diet, or folate-supplemented diet from 1 week before mating until the end of pregnancy. A fourth group fed folate-normal diet from 1 week before mating until mating, then fed folate-supplemented diet for 10 consecutive days, then fed folate-normal diet until the end of pregnancy. Offspring were sacrificed on postnatal day 0 for measurement of neurogenesis and synaptogenesis by immunofluorescence and western blot. Additionally neural stem cells (NSCs) were cultured from offspring's hippocampus for immunocytochemical measurement of their rates of proliferation and neuronal differentiation. The results demonstrated that maternal folic acid supplementation stimulated hippocampal neurogenesis by increasing proliferation and neuronal differentiation of NSCs, and also enhanced synaptogenesis in cerebral cortex of neonatal offspring. Hippocampal neurogenesis was stimulated more when supplementation was continued throughout pregnancy instead of being limited to the periconceptional period. In conclusion, maternal folic acid supplementation, especially if continued throughout pregnancy, improves neurogenesis and synaptogenesis in neonatal offspring.

Long-term ginsenoside Rg1 supplementation improves age-related cognitive decline by promoting synaptic plasticity associated protein expression in C57BL/6J mice.

In aging individuals, age-related cognitive decline is the most common cause of memory impairment. Among the remedies, ginsenoside Rg1, a major active component of ginseng, is often recommended for its antiaging effects. However, its role in improving cognitive decline during normal aging remains unknown and its molecular mechanism partially understood. This study employed a scheme of Rg1 supplementation for female C57BL/6J mice, which started at the age of 12 months and ended at 24 months, to investigate the effects of Rg1 supplementation on the cognitive performance. We found that Rg1 supplementation improved the performance of aged mice in behavior test and significantly upregulated the expression of synaptic plasticity-associated proteins in hippocampus, including synaptophysin, N-methyl-D-aspartate receptor subunit 1, postsynaptic density-95, and calcium/calmodulin-dependent protein kinase II alpha, via promoting mammalian target of rapamycin pathway activation. These data provide further support for Rg1 treatment of cognitive degeneration during aging.

Pueraria mirifica, phytoestrogen-induced change in synaptophysin expression via estrogen receptor in rat hippocampal neuron.

OBJECTIVE: To examine Pueraria mirifica (Leguminosae) containing-phytoestrogen effect on synaptic density and involvement of estrogen receptor. MATERIAL AND METHOD: The level of synaptophysin, a presynaptic vesicle protein, was measured using Western blot analysis and immunocytochemistry in hippocampal primary cell cultures at 6 days in vitro. RESULTS: P. mirifica and 17beta-estradiol (0.1 microM) treatment for 4 days, but not for 2 days, significantly increased synaptophysin immunoreactivity and level of synaptophysin. P. mirifica up to 60 microg/ml resulted in a dose related increase in the level of synaptophysin immunoreactivity. The classical estrogen receptor antagonist, ICI 182 780, significantly blocked P. mirifica-induced increase in synaptophysin. CONCLUSION: P. mirifica-containing phytoestrogen affects synaptic density by inducing synaptophysin expression via estrogen receptor.

Antagonizing beta-amyloid peptide neurotoxicity of the anti-aging fungus Ganoderma lucidum.

Ganoderma lucidum (Leyss. ex Fr.) Karst. (Lingzhi) is a medicinal fungus used clinically in many Asian countries to promote health and longevity. Synaptic degeneration is another key mode of neurodegeneration in Alzheimer's disease (AD). Recent studies have shown the loss of synaptic density proteins in each individual neuron during the progression of AD. It was recently reported that beta-amyloid (Abeta) could cause synaptic dysfunction and contribute to AD pathology. In this study, we reported that aqueous extract of G. lucidum significantly attenuated Abeta-induced synaptotoxicity by preserving the synaptic density protein, synaptophysin. In addition, G. lucidum aqueous extract antagonized Abeta-triggered DEVD cleavage activities in a dose-dependent manner. Further studies elucidated that phosphorylation of c-Jun N-terminal kinase, c-Jun, and p38 MAP kinase was attenuated by G. lucidum in Abeta-stressed neurons. Taken together, the results prove a hypothesis that anti-aging G. lucidum can prevent harmful effects of the exterminating toxin Abeta in AD.

Catalpol increases hippocampal neuroplasticity and up-regulates PKC and BDNF in the aged rats.

Rehmannia, a traditional Chinese medical herb, has a long history in age-related disease therapy. Previous work has indicated that catalpol is a main active ingredient performing neuroprotective effect in rehmannia, while the mechanism underlying the effect remains poorly understood. In this study, we attempt to investigate the effect of catalpol on presynaptic proteins and explore a potential mechanism. The hippocampal levels of GAP-43 and synaptophysin in 3 groups of 4 months (young group), 22-24 months (aged group) and catalpol-treated 22-24 months (catalpol-treated group) rats were evaluated by western blotting. Results clearly showed a significant decrease in synaptophysin (46.6%) and GAP-43 (61.4%) levels in the aged group against the young animals and an increase (45.0% and 31.8% respectively) in the catalpol-treated aged rats in comparison with the untreated aged group. In particular, synaptophysin immunoreactivity (OD) in the dentate granule layer of the hippocampus was increased 0.0251 in the catalpol-treated group as compared with the aged group. The study also revealed a catalpol-associated increase of PKC and BDNF in the hippocampus of the catalpol-treated group in comparison with the aged rats and highly correlated with synaptophysin and GAP-43. Such positive correlations between presynaptic proteins and signaling molecules also existed in the young group. These results suggested that catalpol could increase presynaptic proteins and up-regulate relative signaling molecules in the hippocampus of the aged rats. Consequently, it seemed to indicate that catalpol might ameliorate age-related neuroplasticity loss by "normalizing" presynaptic proteins and their relative signaling pathways in the aged rats.

alpha-Tocopherol affects neuronal plasticity in adult rat dentate gyrus: the possible role of PKCdelta.

Hippocampus dentate gyrus (DG) is characterized by neuronal plasticity processes in adulthood, and polysialylation of NCAM promotes neuronal plasticity. In previous investigations we found that alpha-tocopherol increased the PSA-NCAM-positive granule cell number in adult rat DG, suggesting that alpha-tocopherol may enhance neuronal plasticity. To verify this hypothesis, in the present study, structural remodeling in adult rat DG was investigated under alpha-tocopherol supplementation conditions. PSA-NCAM expression was evaluated by Western blotting, evaluation of PSA-NCAM-positive granule cell density, and morphometric analysis of PSA-NCAM-positive processes. In addition, the optical density of synaptophysin immunoreactivity and the synaptic profile density, examined by electron microscopy, were evaluated. Moreover, considering that PSA-NCAM expression has been found to be related to PKCdelta activity and alpha-tocopherol has been shown to inhibit PKC activity in vitro, Western blotting and immunohistochemistry followed by densitometry were used to analyze PKC. Our results demonstrated that an increase in PSA-NCAM expression and optical density of DG molecular layer synaptophysin immunoreactivity occurred in alpha-tocopherol-treated rats. Electron microscopy analysis showed that the increase in synaptophysin expression was related to an increase in synaptic profile density. In addition, Western blotting revealed a decrease in phospho-PKC Pan and phospho-PKCdelta, demonstrating that alpha-tocopherol is also able to inhibit PKC activity in vivo. Likewise, immunoreactivity for the active form of PKCdelta was lower in alpha-tocopherol-treated rats than in controls, while no changes were found in PKCdelta expression. These results demonstrate that alpha-tocopherol is an exogenous factor affecting neuronal plasticity in adult rat DG, possibly through PKCdelta inhibition.

Stress (hypothalamic-pituitary-adrenal axis) and pain response in male rats exposed lifelong to high vs. low phytoestrogen diets.

Estrogens exhibit complex but beneficial effects on brain structure, function and behavior. Soy-derived dietary phytoestrogens protect against hormone-dependent and age-related diseases, due to their estrogen-like hormonal actions. However, the effects of phytoestrogens on brain and behavior are relatively unknown. This study examined the influence of exposing male Long-Evans rats (lifelong) to either a phytoestrogen-rich (Phyto-600) or a phytoestrogen-free (Phyto-free) diet on body weights, behavioral pain thresholds, the hypothalamic-pituitary-adrenal (HPA) hormonal stress response, hippocampal glucocorticoid receptor and brain neural cell adhesion molecules (NCAM) and synaptophysin levels using standard behavioral and biochemical techniques. Body weights were significantly decreased in Phyto-600 fed animals compared to Phyto-free values. There were no significant changes in behavioral pain thresholds, circulating corticosterone concentrations (after acute immobilization stress) or NCAM and synaptophysin levels in various brain regions by the diet treatments. However, Phyto-600 fed males displayed significantly higher plasma adrenocorticotrophin (ACTH) (post-stress) and hippocampal glucocorticoid receptor levels vs. Phyto-free values. These data suggest that (1) body weights are significantly reduced by soy-derived phytoestrogens, (2) behavioral pain thresholds (via heat stimuli) are not influenced by dietary phytoestrogens, but (3) these estrogenic molecules in the hippocampus enhance glucocorticoid receptor abundance and alter the negative feedback of stress hormones towards a female-like pattern of higher ACTH release after activation of the HPA stress axis. This study is the first to show that lifelong consumption of dietary phytoestrogens alters the HPA stress response in male rats.