Changes of autologous neural stem cells in the hippocampi of aging mice

Diet-induced changes in brain structure and behavior in old gerbils

Background/Objectives:

Aging is associated with many physiological alterations such as changes in metabolism, food intake and brain dysfunction. Possible ways to correct age-related brain dysfunction using dietary treatments still remains undeveloped. The aim of our research was to investigate whether long-term dietary treatment with 2-oxoglutarate (2-OX), which is involved in many regulatory pathways, together with pancreatic-like enzymes of microbial origin (PLEM), which ensure appropriate digestion and absorption of nutrients, affects age-related changes in the brain morphology and cognitive function in old Mongolian gerbils.

Materials/methods:

Experiment was comprised of two separate studies. Samples of the hippocampus were obtained from male Mongolian gerbils of different ages (n=63 in the first study, n=74 in the second study). Immunohistochemistry was used for visualization of the nestin/NeuN-positive neuronal progenitors. Changes in amount of neural cell adhesion molecules (NCAMs) were estimated using enzyme-linked immunosorbent assay. For assessment of cognitive and sensorimotor functions, the T-maze spontaneous alternation test and the adhesive removal test (ART) were used. The ultrastructure of the CA1 hippocampal area was visualized using transmission electron microscopy.

Results:

Long-term treatment with 2-OX+PLEM led to a significantly increased amount of nestin/NeuN-positive cells in the CA1 hippocampal area and positive changes in learning and sensorimotor functions. As for synaptic transmission, changes in the spatial distribution of synaptic vesicles, as well as the redistribution of NCAM forms, were observed in the hippocampal synapses of the old gerbils.

Conclusions:

Taken together, our data show that dietary supplementation with 2-OX+PLEM not only enhances the proliferation and differentiation of neuronal progenitors, but also improves age-related deficits in the morphological and functional state of the brain of old gerbils. Thus, suggesting that a 2-OX+PLEM-enriched diet could also improve brain functions that have deteriorated with age.

Effects of Chinese herbal medicine Fuzhisan on autologous neural stem cells in the brain of SAMP-8 mice

Fuzhisan (FZS), a Chinese herbal complex prescription, has been used in the treatment of Alzheimer's disease (AD) for more than 16 years. However the underlying mechanism remains to be explored. The effects of the aqueous extract of FZS on the cognitive functions of the aged mice and the pharmacological basis for its therapeutic efficacy were investigated. The results showed that FZS improved impaired cognitive ability of aged SAMP-8 mice. FZS (2.4, 4.8 g/kg/d) increased hippocampal neurogenesis and the long-term survival of BrdU-labeled cells without affecting the proportion of BrdU-positive neurons and glial cells. FZS also increased the number of BrdU-positive cells in the subventricular zone (SVZ) of the lateral ventricles of 8-month-old SAMP-8 mice. These studies suggest that FZS upregulates neurogenesis by increasing proliferation of neural progenitor cells and prolonging survival of the newborn cells in the hippocampal DG. FZS may be beneficial for the treatment of senile dementia, especially Alzheimer's disease.

Stem cells and neuroprotection: understanding the players

The use of neuroprotective therapies begs the question of how such therapies could affect preexisting stem cell populations within the host, as well as those introduced through cell-replacement therapy. Multiple mechanisms may mediate stem cell responses to neuroprotectants such as host/donor age and gender, cellular lineage/differentiation status, and mitochondrial dynamics. Current therapeutic sources for stem cells are embryonic, somatic, or induced pluripotent, with very little known about the effects of gender, age, cell type, and mitochondrial dynamics. With the advent of therapies to stimulate and recruit endogenous stem cells or transplant donor cells into damage areas in the hopes of recuperative regeneration of lost neurons, it is important to discuss mechanisms that dictate the winning players in the neuroprotection game. This review will focus on our current understanding of the characteristics of renewing stem cells that may affect neuroprotection.