Abstract: AIMTo investigate mRNA expression changes of voltage-gated outward potassium channel subtypes in cultured rat hippocampal neurons after chronic exposure to β-amyloid-petitde_25-35 (β-AP_25-35). METHODSmRNA expression was detected by RT-PCR, comparative expression levels were determined by imaging densitometer. RESULTS Delayed rectifying (Kv2.1, Kv1.5), transient outward (Kv1.4, Kv4.2) and large conductance calcium-activated (rSlo) potassium channel mRNA were expressed in cultured rat hippocampal. In the presence of β-AP_25-35 3 μmol·L^-1 for 24 h, the relative expression level of Kv2.1 was significantly increased (N=3, P<0.05); the other subtypes were not changed obviously (N=3, P>0.05). The increase of Kv2.1 mRNA mainly happened between 24 and 36 h after exposure to β-AP_25-35. After exposure to β-AP_25-35 for 60 h, Kv2.1 mRNA decreased significantly (N=3, P<0.01). CONCLUSIONThe upregulation of Kv2.1 on transcription levels may be involved in the enhancement of delayed rectifying outward potassium (I_K) current induced by β-AP_25-35.