Progress in application of adult endogenous neurogenesis in brain injury repair / 生理学报

Persistent neurogenesis exists in the subventricular zone (SVZ) of the ventricles and the subgranular zone (SGZ) of the dentate gyrus of the hippocampus in the adult mammalian brain. Adult endogenous neurogenesis not only plays an important role in the normal brain function, but also has important significance in the repair and treatment of brain injury or brain diseases. This article reviews the process of adult endogenous neurogenesis and its application in the repair of traumatic brain injury (TBI) or ischemic stroke, and discusses the strategies of activating adult endogenous neurogenesis to repair brain injury and its practical significance in promoting functional recovery after brain injury.

Anatomical analysis of muscle spindles in tibialis anterior and extensor digitorum longus muscle of C57BL/6 mice / 解剖学报

Objective To locate the distribution of muscle spindles in tibialis anterior (TA) and extensor digitorum longus muscle (EDL) and the anchoring mode of muscle spindles in skeletal muscles, and perform statistics analysis of their morphological character by anatomical parameters. Methods Five adult wild type C57BL/6 mice were sacrificed, and TA and EDL were dissected and frozen with improved ultra-low temperature cryopreservation technology avoiding myofibers damaged by possible ice crystal. Continuous frozen transections were obtained and operated by HE staining, followed by microimaging to spot the muscle spindles location. Some parameters including regions length and cross section area (CSA) of muscle spindles were noticed for the discovery of some general characteristics of spindles by statistics. Results For TA and EDL, the scattered characters of muscle spindles were distributed as follows: the spindles were located at the upper third of the mid-belly of both TA and EDL from caudal to rostral position, while near the enter point to muscle of the deep peroneal nerve in dorsal-ventral orientation. The peripheral of muscle spindles anchored to extrafusal fibers to hold in the muscle. And in term of length, region A, connected with sensory nerve ending, demonstrated a significant correlation with region B, which located at the poles of region A and twined by motor nerve ending (correlation index = 0. 75) when considering the muscle spindles with four intrafusal fibers only. And no correlation was discovered in any others pairwise parameters. Conclusion The scattered diagram of muscle spindles in TA and EDL of C57BL/6 mice might provide anatomic basis for evaluation of lower limb motor function, especially for the spinal cord injury and recovery research. And the correlationship between the length of region A and B might improve exploring the variability of electrophysiological characters.

Electrophysiological characteristics of hippocampal postnatal early development mediated by AMPA receptors in rats / 生理学报

The present study was aimed to investigate the electrophysiological characteristics of hippocampal postnatal early development mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in rats. Forty-eight Wistar rats were divided into postnatal 0.5-, 1-, 2- and 3-month groups (n = 12). Spontaneous excitatory postsynaptic currents (sEPSCs) and field excitatory postsynaptic potentials (fEPSPs) mediated by AMPA receptors were recorded to evaluate the changes in the intrinsic membrane properties of hippocampal CA1 pyramidal neurons by using patch-clamp and MED64 planar microelectrode array technique respectively. The results showed that, during the period of postnatal 0.5-3 months, some of the intrinsic membrane properties of hippocampal CA1 pyramidal neurons, such as the membrane capacitance (Cm) and the resting membrane potential (RMP), showed no significant changes, while the membrane input resistance (Rin) and the time constant (τ) of the cells were decreased significantly. The amplitude, frequency and kinetics (both rise and decay times) of sEPSCs were significantly increased during the period of postnatal 0.5-1 month, but they were all decreased during the period of postnatal 1-3 months. In addition, the range of evoked fEPSPs in hippocamal CA1 region was significantly expanded, but the fEPSP amplitudes were decreased significantly during the period of postnatal 0.5-3 months. Furthermore, the evoked fEPSPs could be significantly inhibited by extracellular application of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). These results suggest that AMPA receptor may act as a major type of excitatory receptor to regulate synaptic transmission and connections during the early stage of hippocampal postnatal development, which promotes the development and functional maturation of hippocampus in rats.

High-proportion differentiation of neural stem cells into neurons and formation of neural networks induced by active biomaterial scaffolds in vitro / 中国组织工程研究

BACKGROUND: Either good biocompatibility and biological activity of active biological materials or the potential of multidirectional differentiation of neural stem cells has great application prospect and value. OBJECTIVE: To investigate the effect of neurotrophic factor 3-chitosan active biomaterial scaffolds on the differentiation of neural stem cells and the expression of key proteins of the neurotrophic factor 3 signal pathway in vitro. METHODS: The neural stem cells were extracted and purified, and then divided into pure culture medium group, soluble neurotrophic factor 3 group, pure chitosan group, and neurotrophic factor 3-chitosan group for differentiation induction. The expression of TrkC, Akt / p-Akt and Erk/p-Erk in the neurotrophic factor 3 signaling pathway was detected by western blot after 6 hours of induction. After 7 days of induction, differentiation of neural stem cells was observed by immunocytochemistry of MAP2, MBP, and GFAP. After 14 days of induction, formation of neural network induced by neurotrophic factor 3-chitosan active biomaterials was observed by immunocytochemistry of MAP2, Synapsin-1, and PSD95. RESULTS AND CONCLUSION: The neurotrophic factor 3-chitosan group induced a high proportion of neural stem cells differentiated into neurons, with a ratio of 73.8%, which was significantly higher than that in the other three groups. Meanwhile, the proportion of cells differentiated into glial cells waslower than that in the other three groups. The expression of key proteins TrkC, p-Akt and p-Erk in the neurotrophic factor 3-chitosan group was higher than that in the other three groups. Meanwhile, neurotrophic factor 3-chitosan could induce the in vitro differentiation of neural stem cells to form neural network.