title: Modulation of Ca²⁺ signals by epigallocatechin-3-gallate(EGCG) in cultured rat hippocampal neurons.
abstract: Green tea has been receiving considerable attention as a possible neuroprotective agent against neurodegenerative disease. Epigallocatechin-3-gallate (EGCG) is the major compound of green tea. Calcium signaling has profound effects on almost all aspects of neuronal function. Using digital calcium imaging and patch-clamp technique, we determined the effects of EGCG on Ca(2+) signals in hippocampal neurons. The results indicated that EGCG caused a dose-dependent increase in intracellular Ca(2+) ([Ca(2+)](i)). This [Ca(2+)](i) increase was blocked by depleting intracellular Ca(2+) stores with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin and cyclopiazonic acid. Furthermore, EGCG-stimulated increase in [Ca(2+)](i) was abolished following treatment with a PLC inhibitor. However, EGCG inhibited high-voltage activated Ca(2+) currents (I(HVA)) and NMDA-induced inward currents (I(NMDA)). These data suggest that EGCG triggers a cascade of events: it activates phospholipase C (PLC), mobilizes intracellular Ca(2+) stores, raises the cytosolic Ca(2+) levels, and inhibits the VGCC and NMDA receptors-mediated Ca(2+) influx through a process that remains to be determined.
authors.affiliation: College of Fisheries, Huazhong Agricultural University, Wuhan 430070, Hubei, China; E-Mail: whtjwjh@163.com.
authors.forename: Jiang-Hua
authors.initials: JH
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Cheng
authors.forename: Cai-Rong
authors.initials: CR
authors.lastname: Li
authors.forename: Mao
authors.initials: M
authors.lastname: Ye
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ma
authors.forename: Fei
authors.initials: F
authors.lastname: Cai
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D006624:Hippocampus / Q000166:cytology*; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D002392:Catechin; C045651:epigallocatechin gallate; D010738:Type C Phospholipases