Astragalus protects PC12 cells from 6-hydroxydopamine-induced neuronal damage: A serum pharmacological study.

Accumulating evidence has already indicated that traditional Chinese medicine (TCM) possesses tremendous potential for treating neurodegenerative diseases. Astragalus, also named Huangqi, is a famous traditional medical herb that can be applied to treat cerebral ischemia and prevent neuronal degeneration. Nevertheless, the underlying mechanisms remain largely unexplored. In the present study, Astragalus-containing serum (ASMES) was prepared and added into the culture medium of PC12 cells to explore its neuroprotective effect on 6-hydroxydopamine (6-OHDA)-caused neuronal toxicity. Our data showed that ASMES significantly ameliorated the cellular viability of cultured PC12 cells against the neurotoxicity induced by 6-OHDA (P < 0.05). Moreover, ASMES significantly decreased the cell apoptosis triggered by 6-OHDA (P < 0.01). Furthermore, 2',7'-dichlorofluorescin diacetate assay was performed to detect the changes in oxidative stress, and we showed that 6-OHDA elevated the production of reactive oxygen species (ROS), whereas ASMES significantly reversed these changes (P < 0.01). Besides, mitochondrial membrane potential (MMP) assay showed that ASMES could restore 6-OHDA-damaged MMP in cultured PC12 cells (P < 0.05). In conclusion, Astragalus could protect PC12 cells from 6-OHDA-caused neuronal toxicity, and possibly, the ROS-mediated apoptotic pathway participated in this process. Collectively, our findings provided valuable insights into the potential in treatment of neurodegenerative diseases.

Nicotinamide adenine dinucleotide promotes synaptic plasticity gene expression through regulation N-methyl-D-aspartate receptor/Ca2+/Erk1/2 pathway.

Nicotinamide adenine dinucleotide (NADH) has been reported to regulate synaptic plasticity recently, while its role in this process remains unclear. To explore the contribution and the underlying mechanisms of NADH regulating synaptic plasticity, here, we examined NADH's effect on immediate-early response genes (IEGs) expressions, including C-Fos and Arc in primary cultured cortical neurons and the frontal cortex of mouse brain. Our results showed that NADH promoted IEGs expression and that the C-Fos and Arc levels are increased in primary cultured cortical neurons, which is almost completely blocked by N-methyl-D-aspartate receptor (NMDAR) inhibitor, MK-801. Moreover, NADH significantly increased intracellular Ca2+ levels and the phosphorylation of Erk1/2, a downstream molecule of the NMDAR. Furthermore, NADH also significantly increased IEGs expression in vivo, accompanied by the changes of Ca2+ in neurons and activation of excitatory neurons in the mouse frontal cortex. In conclusion, this study indicates that NADH can promote the expression of synaptic plasticity-related IEGs through the NMDAR/Ca2+/Erk1/2 pathway, which provides a new way to understand the regulatory role of NADH in synaptic plasticity.

Roles of NAD in Protection of Axon against Degeneration via SIRT1 Pathways.

Axonal degeneration is a common pathological change of neurogenical disease which often arises before the neuron death. But it had not found any effective method to protect axon from degeneration. In this study we intended to confirm the protective effect of nicotinamide adenine dinucleotide (NAD), investigate the optimal administration dosage and time of NAD, and identify the relationship between silence signal regulating factor 1 (SIRT1) and axonal degeneration. An axonal degeneration model was established using dorsal root ganglion (DRG) neurons injured by vincristine to observe the protective effects of NAD to the injured axons. In addition, the potential contribution of the SIRT1 in axonal degeneration was also investigated. Through the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, immunochemistry staining, axons counting and length measuring, transmission electron microscope (TEM) observation, we demonstrated that NAD played an important role in preventing axonal degeneration. Further study revealed that the expression of SIRT1 and phosphorylated Akt1 (p-Akt1) was up-regulated when NAD was added into the culturing medium. Taking together, our results demonstrated that NAD might delay the axonal degeneration through SIRT1/Akt1 pathways.

Hyperthermia induces upregulation of connexin43 in the golden hamster neural tube.

BACKGROUND: During early embryonic development, maternal exposure to hyperthermia induces neural tube defects (NTDs). Connexins are essential for the formation of gap junctions and Connexin43 (Cx43) is crucially involved in neural tube development. This study was designed to explore the potential role of Cx43 in NTDs induced by hyperthermia. METHODS: Using PCR, the Cx43 cDNA was screened from the cDNA library of the neural tube from golden hamsters treated with hyperthermia. By Northern blot, the expression of Cx43 in heat-treated and control groups of the golden hamsters at day 8.5 after mating was detected. Finally, by in situ hybridization and RT-PCR, the expression of Cx43 was examined in the neural tube at different time points after heat treatment. RESULTS: Cx43 was stably expressed in heat-treated and control groups of the golden hamsters, whereas the expression was evidently higher in the heat-treated group. Cx43 expression in the neural tube at different time points after heat treatment was significantly higher than in control groups (p < 0.01). Hyperthermia did not induce any mutations in Cx43 cDNA. CONCLUSIONS: Our data provide the first evidence that hyperthermia induces upregulation of Cx43 in the golden hamster neural tube. NTDs caused by hyperthermia may be intimately related with the overexpression of Cx43.

Survival and differentiation of neuroepithelial stem cells on chitosan bicomponent fibers.

Chitosan is a popular biomaterial used in tissue engineering. Fibers of chitosan could provide a favorable anatomical substrate for cell growth which provides a promising application for axonal regeneration during peripheral injury. Neuroepithelial stem cells (NEPs) are the most primitive neural stem cells with multipotential for neuronal and glia differentiation. To assess the biocompatibility between NEPs and chitosan fibers, and to explore whether the NEPs have the ability to differentiation on chitosan fibers, NEPs were harvested from the neural tube and seeded on chitosan fibers in in vitro culture. The biocompatibility of chitosan fibers was tested by MTT assays. The growth and survival were observed by light and scanning electronic microscope at different times in culture. And, the differentiation of NEPs was examined by immunocytochemical staining. The results indicated that NEPs could grow on the chitosan fibers and attach firmly to the surface of fibers. On chitosan fibers, NEPs could differentiate into neurons and glia. Our study demonstrated that chitasan fibers had a good biocompatibility with NEPs which affords a potential alternative for the repair of peripheral nerve injury.

Survival and differentiation of neuroepithelial stem cells following transplantation into the lateral ventricle of rats.

Neuroepithelial stem cells (NEPs) demonstrate a high potential for self-renewal and differentiation during embryonic development. To explore the survival and differentiation of NEPs in vivo, we isolated NEPs from green fluorescence protein (GFP) transgenic embryos and transplanted into the lateral ventricle of rats. In vitro culture, NEPs proliferated into neurospheres and differentiated into both neurons and glia. When transplanted into the lateral ventricle of rats, these GFP positive NEPs (GFP+ NEPs) survived and attached to the wall of ventricle. Moreover, grafted cells differentiated into neuron-specific enolase (NSE) positive neurons and glial fibrillary acidic protein (GFAP) positive astrocytes and migrated into the host brain. Thus, our results indicate that NEPs can survive and differentiate into neurons and astrocytes in the lateral ventricle following transplantation.

Effects of Buyang Huanwu Decoction on neurite outgrowth and differentiation of neuroepithelial stem cells.

To determine the effects of Buyang Huanwu Decoction (BYHWD), a traditional Chinese medicine, on neurite outgrowth and differentiation of neuroepithelial stem cells (NEPs), NEPs were isolated from embryonic neural tube and cultured in medium with rat serum containing BYHWD, which was prepared from rats administrated orally with BYHWD. The average neurite length of NEPs grew significantly longer in rat serum containing BYHWD than in control serum without BYHWD. More neurofilament (NF) positive cells and glial fibrillary acidic protein (GFAP) positive cells were detected in NEPs cultured in the presence of BYHWD. Besides, when cultured NEPs were loaded with Fluo-3-AM, the fluorescence intensity obtained from NEPs cultured in serum with BYHWD was significantly lower than that from NEPs cultured in control serum without BYHWD. Our results indicate that BYHWD could exert a promotion effect on neurite outgrowth and differentiation of NEPs.

A general principle governs vision-dependent dendritic patterning of retinal ganglion cells.

Dendritic arbors of retinal ganglion cells (RGCs) collect information over a certain area of the visual scene. The coverage territory and the arbor density of dendrites determine what fraction of the visual field is sampled by a single cell and at what resolution. However, it is not clear whether visual stimulation is required for the establishment of branching patterns of RGCs, and whether a general principle directs the dendritic patterning of diverse RGCs. By analyzing the geometric structures of RGC dendrites, we found that dendritic arbors of RGCs underwent a substantial spatial rearrangement after eye-opening. Light deprivation blocked both the dendritic growth and the branch patterning, suggesting that visual stimulation is required for the acquisition of specific branching patterns of RGCs. We further showed that vision-dependent dendritic growth and arbor refinement occurred mainly in the middle portion of the dendritic tree. This nonproportional growth and selective refinement suggest that the late-stage dendritic development of RGCs is not a passive stretching with the growth of eyes, but rather an active process of selective growth/elimination of dendritic arbors of RGCs driven by visual activity. Finally, our data showed that there was a power law relationship between the coverage territory and dendritic arbor density of RGCs on a cell-by-cell basis. RGCs were systematically less dense when they cover larger territories regardless of their cell type, retinal location, or developmental stage. These results suggest that a general structural design principle directs the vision-dependent patterning of RGC dendrites.