This study aims to explore the expression of GRP78, a marker of endoplasmic reticulum (ER) stress, in the cortex of rat brains acutely exposed to methylmercury (MeHg). Thirty Sprague-Dawley (SD) rats were randomly divided into six groups, and decapitated 6 hours (h) after intraperitoneal (i.p.) injection of MeHg (2, 4, 6, 8 or 10 mg/kg body weight) or normal saline. Protein and mRNA expression of Grp78 were detected by western blotting and real-time PCR, respectively. The results showed that a gradual increase in GRP78 protein expression was observed in the cortex of rats acutely exposed to MeHg (2, 4 or 6 mg/kg). Protein levels peaked in the 6 mg/kg group (p < 0.05 vs. controls), decreased in the 8 mg/kg group, and bottomed below the control level in the 10 mg/kg group. Parallel changes were noted for Grp78 mRNA expression. It may be implied that acute exposure to MeHg induced hormetic dose-dependent changes in Grp78 mRNA and protein expression, suggesting that activation of ER stress is involved in MeHg-induced neurotoxicity. Low level MeHg exposure may induce GRP78 protein expression to stimulate endogenous cytoprotective mechanisms.
Zhang, Ye; Lu, Rongzhu; Liu, Wenshuai; Wu, Ying; Qian, Hai; Zhao, Xiaowu; Wang, Suhua; Xing, Guangwei; Yu, Fing; and Aschner, Michael
"HORMETIC EFFECTS OF ACUTE METHYLMERCURY EXPOSURE ON GRP78 EXPRESSION IN RAT BRAIN CORTEX,"
Dose-Response: An International Journal: Vol. 11
, Article 12.
Available at: http://scholarworks.umass.edu/dose_response/vol11/iss1/12