Objective:To observe the effects of lead on levels ofphosphorylated extracellular signal regulated kinase (p-ERK) in the cytoplasm of primary cultures of rat astroglial cells and the possible protective effect of basic fibroblast growth factor (bFGF)on lead-induced effects.Methods:The primary astroglia cells from 1～6 d old Wistar rats were cultured.The cells pretreated with the MEK1 (mitogen-activated protein kinase kinase 1) inhibitor PD98059 and bFGF,respectively,were exposed to Pb acetate of different concentrations for different times.Western blotting and reverse transcription polymerase chain reaction (RT-PCR)methods were used to detect the protein and mRNA expressions of ERK.Results:mRNA expression for ERK peaked 15 min after initiation of lead exposure (P＜0.05) and protein expression of p-ERK peaked at 30 min (P＜0.05).ERK mRNA levels and p-ERK protein levels returned to baseline after 60 and 120 min of lead exposure,respectively (P＞0.05).The increase in p-ERK levels in lead-treated cells could be inhibited by PD098059.Activation of ERK in the cells by lead was prevented by pretreatment with bFGF.Total ERK protein levels did not change under the same experimental conditions (P＞0.05).Conclusion:Low-level lead exposure resulted in transient activation of ERK through the MEK pathway,which then returned to basal levels in the continued presence of lead.Exogenous bFGF protected ERK signaling components in astroglia from lead poisoning.