There are two types of cells in the central nervous systems (CNS) of mammals-neurons and glia. The structure and function of neurons have been thoroughly studied; while the role of glia in information processing has not been systematically studied because they cannot produce action potentials like neuron. During the past decades, glial cells were considered to play a supportive role in CNS instead of information processing. Recently, a variety of studies suggest that glial cells are actively involved in the regulation of brain function associated with neurons. Glial cells, especially astrocytes play important roles in different sensory processing. In the present article, we review the role of astrocytes in sensory processing in the CNS.
Animals ; Astrocytes ; cytology ; physiology ; Central Nervous System ; physiology ; Humans ; Sensation ; physiology ; Synapses ; physiology

OBJECTIVE: To demonstrate the spatial organization of neurons, astrocytes and vessels in rat brain. METHODS: Cerebral vascular was shown by vivi-perfusion with ink. Glial fibrillary acidic protein (GFAP) immunohistochemistry and nissl's staining were performed on the serial sections of frozen brain tissues. RESULTS: Astracytes distributed along the branches of blood vessels, and neurons in the region of the relatively rich blood vessels. Neurons and astrocytes presented regional distribution. CONCLUSION This method can well indicate the spatial organization of neurovascular unit, the regional differences in the distribution may be related to physical activities and the corresponding adjustment function.
Animals ; Astrocytes ; cytology ; physiology ; Brain ; cytology ; physiology ; Cerebrovascular Circulation ; physiology ; Female ; Glial Fibrillary Acidic Protein ; biosynthesis ; Male ; Neurons ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley

The regulation of astroglia on synaptic plasticity in the CA1 region of rat hippocampus was examined. Rats were divided into three groups: the newly born (< 24 h), the juvenile (28-30 days) and the adult groups (90 - 100 days), with each group having 20 animals. The CA1 region of rat hippocampus was immunohistochemically and electron-microscopically examined, respectively, for the growth of astroglia and the ultrastructure of synapses. The high performance liquid chromatography was employed to determine the cholesterol content of rat hippocampus. In the newly-born rats, a large number of neurons were noted in the hippocampal CA1 region of the newly-born rats, and few astroglia and no synaptic structure were observed. In the juvenile group, a few astroglias and some immature synapses were found, which were less than those in adult rats (P < 0.01). The cholesterol content was 2.92 +/- 0.03 mg/g, 11.20 +/- 3.41 mg/g and 12.91 +/- 1.25 mg/g for newly born, the juvenile and the adult groups, respectively, with the differences among them being statistically significant (P < 0.01). Our study suggests that the astrocytes may play an important role in the synaptic formation and functional maturity of hippocampal neurons, which may be related to the secretion of cholesterol from astrocytes.
Age Factors ; Animals, Newborn ; Astrocytes/cytology ; Astrocytes/metabolism ; Astrocytes/*physiology ; CA1 Region, Hippocampal/*physiology ; CA1 Region, Hippocampal/*ultrastructure ; Cell Communication/physiology ; Cholesterol/metabolism ; Neuronal Plasticity/*physiology ; Random Allocation ; Rats, Wistar ; Synapses/*physiology ; Synapses/ultrastructure

BACKGROUNDThe production of neural stem cells (NSCs) derived from embryonic stem (ES) cells was usually very low according to previous studies, which was a major obstacle for meeting the needs of clinical application. This study aimed at investigating whether astrocytes could promote production of NSCs derived from ES cells in vitro.

METHODSMouse ES cells line-D3 was used to differentiate into NSCs with astrocytes as inducing stromal cells by means of three-stage differentiation procedure. Another group without astrocytes served as control. The totipotency of ES cells was identified by observation of cells' morphology and formation of teratoma in severe combined immunodeficiency disease (SCID) mice. The quantity and purity of NSCs derived from ES cells were analyzed using clonogenic assay, immunohistochemical staining and flow cytometry assay. The plasticity of NSCs was detected by differentiating test. Octamer-binding transcription factor 4 (Oct-4) and nestin, the specific marker genes of ES cells and NSCs respectively, were detected continuously using reverse transcription-polymerase chain reaction (RT-PCR) method to monitor the process of cell differentiation.

RESULTSThe ES cells of D3 line could maintain the ability of differentiating into cellular derivations of all three primary germ layers after continuous passage culture. At the end of two-stage of inducing process, 23.2 +/- 3.5 neurospheres per plate formed in astrocyte-induced group and only 0.8 +/- 0.3 per plate in the control group (clonogenic assay, P < 0.01), and the ratio of nestin positive cells was (50.2 +/- 2.8)% in astrocyte-induced group and only (1.4 +/- 0.5)% in the control group (flow cytometry, P < 0.01). With the induction undergoing, the expression of Oct-4 gradually decreased and then disappeared, while the expression of nestin was increased step by step, and the ratio of nestin positive cells was up to 91.4% by the three-stage differentiation. The nestin positive cells could be further induced into neurons, astrocytes, and oligodendrocytes in differentiating medium supplemented with fetal calf serum. The results of differentiating test showed that the ratio of NF-200 and NSE positive cells was (42.7 +/- 2.6)% in astrocyte-induced group and only (11.2 +/- 1.8)% in the control group (P < 0.01).

CONCLUSIONSAstrocytes can not only increase the production of NSCs derived from ES cells but also promote the differentiation of NSCs toward neuronal lineage.

Animals ; Astrocytes ; physiology ; Cell Differentiation ; Cell Lineage ; Cells, Cultured ; Embryo, Mammalian ; cytology ; Mice ; Neurons ; cytology ; Stem Cells ; cytology

OBJECTIVETo investigate the apoptosis rules of the astrocytes and oligodendrocytes induced by Ca(2+) reperfusion.

METHODSThe apoptosis of purified cultured astrocytes and oligodendrocytes induced by Ca(2+) reperfusion and the relationship between the development of the cell apoptosis and post-reperfusion time was observed.

RESULTSBoth the astrocytes and oligodendrocytes were obviously in a time-dependent fashion, and the apoptosis ratios of the oligodendrocytes (39.73%+/-4.16%) were higher than the astrocytes (19.64%+/-4.67%) 24 hours after Ca(2+) reperfusion. The TUNEL positive cells were 13.6+/-1.82 and 21.4+/-1.95 at every visual field of astrocytes and oligodendrocytes respectively 24 hours after Ca(2+) reperfusion.

CONCLUSIONSThe astrocytes and oligodendrocytes are similar wi th the development rules on apoptosis and have different susceptiveness to the situation.

Animals ; Apoptosis ; drug effects ; physiology ; Astrocytes ; cytology ; pathology ; physiology ; Calcium ; physiology ; Cells, Cultured ; Flow Cytometry ; In Situ Nick-End Labeling ; Oligodendroglia ; cytology ; pathology ; physiology ; Rats ; Rats, Wistar

Olfactory ensheathing cells (OECs) are a unique type of glia with common properties of astrocyte and Schwann cells. Cultured OECs have two morphological phenotypes, astrocyte-like OECs and Schwann cell-like OECs. Reversible changes have been found between these two morphological phenotypes. However, the molecular mechanism underlying the regulation of these reversible changes is still unknown. The aim of this paper is to establish a method for the morphology plasticity of cultured OECs, and investigate the underlying mechanism. Using the primary culture of OECs and immunocytochemistry, the morphology of OECs was observed under serum, serum free media or dB-cAMP drug treatment. Statistical analysis was performed to test differences among the percentages of OEC subtypes under these conditions. The results showed that under serum free media, (95.2±3.7)% of OECs showed Schwann cell-like morphology, and (4.8±3.7)% of OECs showed astrocyte-like morphology; however, under 10% serum media, (42.5±10.4)% of OECs exhibited Schwann cell-like morphology, and (57.5±10.4)% of OECs exhibited astrocyte-like morphology. When media was changed back to serum free media for 24 h, (94.8±5.0)% of OECs showed Schwann cell-like morphology, and (5.2±5.0)% of OECs showed astrocyte-like morphology. Furthermore, culture condition with or without serum did not affect the expression of OEC cell marker, p-75 and S-100. Finally, dB-cAMP, an analog of cAMP, through inhibiting the formation of F-actin stress fibers and focal adhesion, induced the morphology switch from astrocyte-like to Schwann cell-like morphology under serum condition, promoted the branches and the growth of processes. These results suggest that serum induces the morphology plasticity of cultured OECs, which is mediated by cytoplasmic cAMP level through regulating the formation of F-actin stress fibers and focal adhesion.
Animals ; Astrocytes ; cytology ; physiology ; Cells, Cultured ; Culture Media ; pharmacology ; Cyclic AMP ; physiology ; Male ; Neuroglia ; cytology ; physiology ; Olfactory Bulb ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley ; Schwann Cells ; cytology ; physiology ; Serum ; physiology

Vascular endothelial growth factor (VEGF) was originally recognized as a substance predominantly with vascular permeability and angiogenesis. Recently, more and more evidence indicated that VEGF is expressed in the neurons of the developing and adult brains. Functional investigation demonstrated that VEGF shows several important effects on the neuronal development and physiological function. For example, VEGF accelerates the development of neurons and neural dendritic and axon growth. Besides, VEGF directly and acutely regulates the functions of multiple ion channels of the neuron membrane and changes neural excitability. In traumatic or ischemic injured brains, VEGF produces neuroprotection, enhances capacity of adult neurogenesis and transformation of astroglial cells into new neurons, which are fundamental basis for re-establishment of neural network. Based on the knowledge obtained from the literatures, we propose that VEGF may play very important roles in neural plasticity in the normal brain, and the reconstruction of neurovascular units and neural repair in the traumatic injured brain. This review mainly focuses on neural activity and repair roles of VEGF in adult mammalian brains. Further study on the mechanism of VEGF's neurobiological effects in the brain will be helpful for understanding the regulation of brain functions and developing new therapeutic strategy for prevention of neurodegeneration of the brain.
Animals ; Astrocytes ; cytology ; Brain Injuries ; physiopathology ; Humans ; Neurogenesis ; Neuronal Plasticity ; Neurons ; cytology ; Vascular Endothelial Growth Factor A ; physiology

OBJECTIVETo evaluate the efficiency of a modified culture method for rat cerebral cortical astrocytes in vitro.

METHODSThe astrocytes derived from the cerebral cortex of 3-day-old Sprague-Dawley rats were first purified as described previously, then the cells were replanted at a low density. The culture flask was changed after 1 hour and substratum was replaced after 24 hours. Cells were syncretized to a monolayer, followed by cell passage. After three passages the cells were cultured in DMEM medium containing 10% fetal serum for a long period. The derivation of the cells was identified by immunofluorescent staining with anti-GFAP polyclonal antibodies.

RESULTSA variety of morphologically distinct astrocytes with many long processes and small cell bodies were obtained. Finally an astrocytic network occurred through cellular process connections. The immunofluorescent staining demonstrated the percentage of GFAP-positive cells was above 98%.

CONCLUSIONSThe modified culture method for astrocytes from rat cerebral tissue is reliable, with a high purity. The cultured astrocytes have a similar morphological development to those in vivo.

Animals ; Astrocytes ; physiology ; Cell Culture Techniques ; Cerebral Cortex ; cytology ; Female ; Glial Fibrillary Acidic Protein ; analysis ; Male ; Rats ; Rats, Sprague-Dawley

To observe the influence of tumor necrosis factor-alpha (TNF-alpha) on differentiation of rat mesencephalic neural stem cells (NSCs), the numbers of neurons, astrocytes and oligodendrocytes generated from NSCs were analyzed after differentiation for 3 days by using immunocytochemistry technique. The results show that: (1) TNF-alpha enhanced the proportions of neurons and oligodendrocytes in progeny of NSCs; and (2) TNF-alpha induced the proliferation of oligodendrocytes derived from NSCs, but the proliferation of astrocytes was not influenced by TNF-alpha. We conclude that the TNF-alpha could influence the application of NSCs.
Animals ; Animals, Newborn ; Astrocytes ; cytology ; Cell Differentiation ; physiology ; Cell Proliferation ; Mesencephalon ; cytology ; Neural Stem Cells ; cytology ; Neurons ; cytology ; Oligodendroglia ; cytology ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; physiology

Spinal cord injury (SCI), which is much in the public eye, is still a refractory disease compromising the well-being of both patients and society. In spite of there being many methods dealing with the lesion, there is still a deficiency in comprehensive strategies covering all facets of this damage. Further, we should also mention the structure called the corticospinal tract (CST) which plays a crucial role in the motor responses of organisms, and it will be the focal point of our attention. In this review, we discuss a variety of strategies targeting different dimensions following SCI and some treatments that are especially efficacious to the CST are emphasized. Over recent decades, researchers have developed many effective tactics involving five approaches: (1) tackle more extensive regions; (2) provide a regenerative microenvironment; (3) provide a glial microenvironment; (4) transplantation; and (5) other auxiliary methods, for instance, rehabilitation training and electrical stimulation. We review the basic knowledge on this disease and correlative treatments. In addition, some well-formulated perspectives and hypotheses have been delineated. We emphasize that such a multifaceted problem needs combinatorial approaches, and we analyze some discrepancies in past studies. Finally, for the future, we present numerous brand-new latent tactics which have great promise for curbing SCI.
Animals ; Astrocytes/cytology* ; Axons/physiology* ; Cell Transplantation ; Disease Models, Animal ; Electric Stimulation ; Humans ; Microglia/cytology* ; Motor Neurons/cytology* ; Nerve Regeneration ; Neuroglia/cytology* ; Neuronal Plasticity ; Neurons/cytology* ; Oligodendroglia/cytology* ; Pyramidal Tracts/pathology* ; Recovery of Function ; Regenerative Medicine/methods* ; Spinal Cord Injuries/therapy*