Effects of green tea polyphenols on caveolin-1 of microvessel fragments in rats with cerebral ischemia.

OBJECTIVE

This study was designed to investigate the effects of green tea polyphenols (GTPs) on the permeability of blood-brain barrier (BBB), and the expression of caveolin-1 and extracellular signal-regulated kinase ½ (ERK1/2) after cerebral ischemia.

METHODS

Cerebral ischemia was established by middle cerebral artery occlusion (MCAO). Rats were randomly divided into control and GTP groups, and both included four time points of interest: MCA occluded for 0 hour, 1 hour, 2 hours, and 4 hours groups. After ischemia, triphenyltetrazolium chloride staining and Longa's score were used to determine the infarct volume and neurological deficit. Evans blue (EB) content in the brain tissue was measured to observe the BBB permeability. RT-PCR, immunohistochemistry, and western blot assessment were used to detect expression of caveolin-1 in microvessel fragments of cerebral ischemic tissue. Western blot was also used to examine ERK1/2.

RESULTS

GTPs significantly reduced infarct volume, ameliorated the neurological deficit, and reduced the permeability of BBB. GTPs also obviously reduced the levels of caveolin-1 mRNA and protein expression as well as the expression of phosphorylated ERK1/2 in microvessel fragments of cerebral ischemic tissue, which were enhanced by cerebral ischemia.

DISCUSSION

These data were the first to show that GTPs can decrease the elevated BBB permeability in the ischemic region, and the protective effects for cerebral injury may be related to the reduced expression of caveolin-1 and phosphorylated ERK1/2.