Abstract: Objective To study the change of protein kinase CC(PK CC)content and its mRN A expression level caused by chronic-aluminium exposure,which can damage long-term potentiation(LTP)in CA1 area of hippocampus,to go deep into the mechanism of learning and memory.Methods The ablactated Wistar rats were used to establish the chronic-aluminium exposed models by the gavage of A1Cl3 of differ ent concentrations(0.2%,0.4% and 0.6%)in the drinking water and measured the LTP in hippocampi of the rats,and then deter mined the activity of protein kinase C(P KC)with modified Takai method.Western Blot and RT PCR methods were used to determine the PK CC contents in hippo campi and the mRNA expression level of PK CC.Results(1)The PKC activity of A1Cl3 exposed groups was obviously lower than that of control groups(P<0.01).(2)The content of PK CC in the hippocampi of A 1Cl3-exposed groups fell down compared with that of control groups(P<0.05).(3)The mRNA expression of PKCC in each A1Cl3 exposed group was lower compared with that in control group(P<0.05);And this downwards trend showed dose-dependent and there was distinctive difference between 0.2% and 0.4%,0.6% groups(P<0.05).Conclusion Chronic aluminum exposure can affect not only the mRNA expression of PKCC,but also the expression of PKCC protein,and can reduce the activity of P KC,damage the formation of UP and consequently impaire the ability of learning and memory.