These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Exercise preconditioning reduces brain damage and inhibits TNF-alpha receptor expression after hypoxia/reoxygenation: an in vivo and in vitro study.
    Author: Ding YH, Mrizek M, Lai Q, Wu Y, Reyes R, Li J, Davis WW, Ding Y.
    Journal: Curr Neurovasc Res; 2006 Nov; 3(4):263-71. PubMed ID: 17109621.
    Abstract:
    Exercise reduces ischemia and reperfusion injury in rat stroke models. We investigated whether gradual increases in tumor necrosis factor-alpha (TNF-alpha) reported during exercise down-regulates expression of TNF-alpha receptors I and II (TNFRI and II) in stroke, leading to reduced brain damage. Adult male Sprague Dawley rats were subjected to 30 minutes of exercise on a treadmill each day for 3 weeks. Then, stroke was induced by a 2-hour middle cerebral artery (MCA) occlusion using an intra-luminal filament. Expressions of TNFRI and II mRNA in the brain were detected using a real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Protein expressions of TNFRI and II were determined by enzyme-linked immunoabsorbant assay (ELISA) in serum and brain homogenates. Spatial distribution of TNF-alpha receptors in brain regions was determined with immunocytochemistry. In human umbilical vein endothelial cells (HUVEC), we addressed the causal effect of TNF-alpha pretreatment on TNF I and II expression using ELISA and real-time PCR. In exercised rats after stroke, brain infarct was significantly (p<0.01) reduced in the entire MCA supplied regions, associated with a mild expression of TNFRI and II mRNA and protein. The TNF-alpha receptors were restricted to the ischemic core. In contrast, a robust expression of TNFRI and II molecules was found in non-exercised rats subjected to similar ischemia/reperfusion insults. An in vitro study revealed a causal link between TNF-alpha pretreatment and reduced cellular expression of TNF-alpha receptors under hypoxic/reoxygenated conditions. Our results suggest that reduced-brain damage in ischemic rats after exercise preconditioning may be attributable to the reduced expression of TNF-alpha receptors. Chronically increased TNF-alpha expression was also found to reduce TNFI and II responding to acute ischemia/reperfusion insult.
    [Abstract] [Full Text] [Related] [New Search]