(-)-Epigallocatechin-3‑gallate (EGCG), the predominant constituent of
green tea, has been demonstrated to be neuroprotective against
stroke in rats. However, the precise mechanism of EGCG responsible for neuroprotective activity remains unclear and no established treatment for decreasing the resulting neurological damage of
stroke exists. The present study was designed to investigate the neuroprotective mechanism of EGCG on transient focal
cerebral ischemia in rats. EGCG, when applied immediately following
ischemia, significantly decreased the expression of endoplasmic reticulum stress (ERS)‑related markers, [glucose‑regulated protein 78 (
GRP78), C/EBP‑homologous
protein (CHOP) and caspase‑12] and apoptosis 24 h following reperfusion. EGCG treatment also significantly reduced
infarct volumes and increased neurological scores which was correlated with elevated levels of
TRPC6 and phosphorylation of cAMP/Ca2+ response element‑binding
protein (p‑CREB) activity, and decreased calpain‑specific aII‑spectrin breakdown product (SBDP145) activity. When mitogen‑activated
protein kinase kinase (MEK) activity was specifically inhibited, the
neuroprotective effect of EGCG was attenuated and a correlated decrease in CREB activity was observed. In conclusion, the results clearly demonstrated that intracerebroventricular injection of EGCG immediately following
ischemia, inhibits ERS and improves the neurological status of rats that have undergone
middle cerebral artery occlusion via the inhibition of calpain‑mediated
TRPC6 proteolysis and the subsequent activation of CREB via the
MEK/
extracellular signal-regulated kinases (ERK) pathway.