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

Objective To investigate the effects of mobility training on mobility and the mRNA levels of both synaptophysin and growth associated protein 43 (GAP-43) in the region around an infarction in rats with acute cerebral infarction. Methods Models of cerebral infarction were created in 100 rats through middle cerebral artery occlusion. They were then randomly divided into training and control groups. The motor skill of the rats was examined using a beam walking test. The mRNA levels of both synaptophysin and GAP-43 in the region around the infarction were observed at the 1st, 3rd, 7th, 14th and 28th days after model-creation using a semi-quantitive reverse transcrip-tion polymerase chain reaction. Results The rats' mobility scores increased with training, and significant differ-ences were observed between the average scores of the two groups at the 3rd, 7th and 14th days. The scores were higher in the training group. The mRNA levels of both synaptophysin and GAP-43 in the region around the infarction increased significantly from the 1st to the 3rd and 7th days. Synaptophysin mRNA levels were significantly higher in the trained group at each time point, but the levels of GAP-43 mRNA were significantly higher in the trained group only on the 3rd and 7th days. Conclusions Motor skill and the mRNA levels of synaptophysin and GAP-43 in the region around an infarction can be increased by motor skill training, at least in rats with model acute cerebral infarc-tion.

Objective To investigate the change of and relationship between astrocytes and synapse structure in the region around the infarction area and the roles of the astrocytes on the recovery of motor skill in the experimental rats with acute cerebral infarction after mobility training. Methods A total of 120 rats were randomly divided into 4 groups: a rehabilitation group, an inhibition group, a saline group and a control group. The motor skill of the rats was examined by beam walking test. The changes of astrocytes, synapses, the glial fibrillary acidic protein (GFAP), synaptophysin and growth associated protein 43(GAP-43) in the region around the infarction were observed using electron microscope and immunohistochemistry staining at 7,21 and 42 d after the model was made. Results It was noted that the recovery of motor skill was more significant in the rehabilitation group than that in the control and the inhibition groups (scored in beam walking test at 3.2?0.3 vs 1.8?0.5 and 1.6?0.9 at the third weekend; scored 5.8?0.9 vs 2.6?0.8 and 2.1?0.7scores at the sixth weekend. P

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 (28-30days) 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.