Pre-ischemic treadmill training affects glutamate and gamma aminobutyric acid levels in the striatal dialysate of a rat model of cerebral ischemia.

AIMS: Treadmill training has been shown to improve function in animal models and patients with cerebral ischemia. However, the neurochemical effects of this intervention on the ischemic brain have not been well studied. This study was designed to evaluate the effects of pre-ischemic treadmill training on the release of glutamate and gamma-aminobutyric acid (GABA) from the striatum in a rat middle cerebral artery occlusion (MCAO) model. MAIN METHODS: Rats were divided into five groups: sham control without MCAO, and 0, 1, 2 and 4 weeks pre-ischemic treadmill training. After training, cerebral ischemia was induced by MCAO for 120 min, followed by reperfusion. Microdialysis was used to collect dialysates from the striatum immediately before ischemia, and at 40, 80 and 120 min after ischemia, as well as at 40, 80, 120, 160, 200 and 240 min after reperfusion. KEY FINDINGS: Pre-ischemic treadmill training decreased glutamate release and increased GABA release during the acute phase of cerebral ischemia/reperfusion. Treadmill training for at least 2 weeks produced statistically significant changes in GABA/glutamate release. SIGNIFICANCE: The present study suggests that treadmill training inhibits the excessive release of glutamate, by stimulating GABA release during the acute phase of cerebral ischemia. This may be one of the important mechanisms to protect the striatal neurons from ischemic damage.

[Cloning and analysis of cDNA encoding key enzyme gene (dxr) of the non-MVA pathway in Taxus chinensis cells].

Two distinct routes (classical mevalonate pathway and a novel mevalonate-independent pathway) are utilized by plants for the biosynthesis of isopentenyl diphosphate, the universal precursor of isoprenoids (Fig. 1). Present researches indicated that taxol was synthesized mainly via non-mevalonate pathway, but not genetic evidence was showed. The second step in non-mevalonate pathway involves an intramolecular rearrangement and subsequent reduction of deoxyxylulose phosphate to yield 2-C-methyl-D-erythritol-4-phosphate, and 1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) with responsibility for this reaction was considered as a key enzyme. As a tool for the isolation of genes in terpenoid biosynthesis in plants, total RNA was prepared from Taxus chinensis suspension cells, a cell type highly specialized for diterpene (taxol). A reverse transcription-PCR strategy based on the design of degenerated oligonucleotides was developed for isolating the gene encoding a gymnosperm homolog of this enzyme from Taxus chinensis. Through sequence analysis by Blast P online, the resulting cDNA showed highly homologous to 1-deoxy-D-xylulose 5-phosphate reductoisomerases, with 95% identification compared with Arabidopsis thaliana (Q9XFS9), 94% with Mentha x piperita (Q9XESO), 80% with Synechococcus elongatus (Q8DK30), 78% with Synechocystis sp. PCC 6803 (Q55663) and Nostoc sp. PCC 7120 (Q8YP49), and 73% with Synechococcus leopoliensis (Q9RKT1). Deduced amino acid sequences were also analyzed by PROSITE, ClustalX (1.81) and Phylio (3.6 alpha), and data present evidence for the existence of this deoxyxyluose phosphate reductoisomerase in Taxus chinensis. This is the first report of the dxr gene cloned from gymnosperm.