Aucubin Promotes Differentiation of Neural Precursor Cells into GABAergic Neurons

Aucubin is a small compound naturally found in traditional medicinal herbs with primarily anti-inflammatory and protective effects. In the nervous system, aucubin is reported to be neuroprotective by enhancing neuronal survival and inhibiting apoptotic cell death in cultures and disease models. Our previous data, however, suggest that aucubin facilitates neurite elongation in cultured hippocampal neurons and axonal regrowth in regenerating sciatic nerves. Here, we investigated whether aucubin facilitates the differentiation of neural precursor cells (NPCs) into specific types of neurons. In NPCs cultured primarily from the rat embryonic hippocampus, aucubin significantly elevated the number of GAD65/67 immunoreactive cells and the expression of GAD65/67 proteins was upregulated dramatically by more than three-fold at relatively low concentrations of aucubin (0.01 µM to 10 µM). The expression of both NeuN and vGluT1 of NPCs, the markers for neurons and glutamatergic cells, respectively, and the number of vGluT1 immunoreactive cells also increased with higher concentrations of aucubin (1 µM and 10 µM), but the ratio of the increases was largely lower than GAD expression and GAD immunoreactive cells. The GABAergic differentiation of pax6-expressing late NPCs into GABA-producing cells was further supported in cortical NPCs primarily cultured from transgenic mouse brains, which express recombinant GFP under the control of pax6 promoter. The results suggest that aucubin can be developed as a therapeutic candidate for neurodegenerative disorders caused by the loss of inhibitory GABAergic neurons.

IMMUNOCYTOCHEMIICAL AND MORPHOMETRICAL STUDY OF THE NEURONAL PRECURSOR CELLS DERIVED FROM THE SUBVENTRICULAR ZONE OF THE POSTNATAL RAT FOREBRAIN IN VITRO / 神经解剖学杂志

In order to investigate the chemical and morphornetrical properties of the neuronal precursor cells derived from thesubventricular zone(SVZ) of the postnatal rat forebrain in vitro. The cell-type specific antibodies were used for the immunocy-tochemical staining ,and the morphometric parameters which were the mean soma diameter and the ellipticity index (i. e. , thesmallest soma diameter divided by the largest soma diameter) of every SVZ-derived cell were measured for identifying the pheno-types of the SVZ cells in vitro. The experiment animals were SD rats (weights: 100～ 150 g), the SVZ cells derived from thepostnatal rats were cultured on poly-D-lysine-coated 24-well glass chamber slides in the Neurobasal Medium supplemented withB27 in 5% CO2 at 37 C. The following results were obtained.. At 1 day in vitro, almost all SVZ cells (〉90%) from the postna-tal rat forebrain expressed Tujl, an antibody that recognizes neuron-specific tubulin. Likewise, the preponderance of the SVZcells expressed the polysialylated neural cell adhesion molecule (PSA-N-CAM) ; The majority of the SVZ Tujl-positive cells cul-tured were the cells that had oval-shaped bodies with two short, unbranched processes protruded from every two poles, theirmean soma diameter were 8.42±1.03μm and their ellipticity index were 0.57±0.12. Meanwhile, there were approximately20% of the SVZ cells in culture that were sphere-shaped cells with mean soma diameter 7.20±l.04 μm , and it might be observed that these cells connected with one another. As the time in culture went on, these sphere-shaped SVZ-derived cells alsotransformed to oval-shaped ones as described above, but it could be observed that the cells were still connected in the processesof them. By 3 and 5 days in culture, the SVZ cells had larger cell somas (average diameter 9. 07±1.07 μm), and often consider-ably longer processes but still with few branches. Immunocytochemical staining revealed that the majority of the SVZ cells in cul-ture remained Tujl-positive, PSA-N-CAM-positive. By 7 days in culture, the Tujl-positive cells in culture showed remarkablemorphological changes, and possessed typical neuronal phenotypes, which had more larger cell somas (average diameter 12.8 ±1.13 μm), and had more longer, branched processes. Our results showed that the SVZ in the postnatal SD rats contained theneuronal precursor cells which were PSA-N-CAM-positive and could differentiate into new neurons in vitro.