Abstract
Insulin-like growth factor 1 (IGF-1) has important functions in the brain, including metabolic, neurotrophic, neuromodulatory, and neuroendocrine actions, and it is also prevents amyloid β-induced death of hippocampal neurons. However, its functions on the voltage-gated ion channels in hippocampus remain uncertain. In the present study, we investigated the effects of IGF-1 on voltage-gated potassium, sodium, and calcium channels in the cultured rat hippocampal neurons using the whole-cell patch clamp recordings. Following incubation with different doses of IGF-1 for 24 h, a block of the peak transient A-type K + currents amplitude (IC 50: 4.425 ng/ml, Hill coefficient: 0.621) was observed. In addition, after the application of IGF-1, the amplitude of high-voltage activated Ca 2+ currents significantly increased but activation kinetics did not significantly alter ( V 1/2: −33.45 ± 1.32 mV, k = 6.16 ± 1.05) compared to control conditions ( V 1/2: −33.19 ± 2.28 mV, k = 7.26 ± 1.71). However, the amplitude of Na +, K +, and low-voltage activated Ca 2+ currents was not affected by the application of IGF-1. These data suggest that IGF-1 inhibits transient A-type K + currents and enhances high-voltage-activated Ca 2+ currents, but has no effects on Na + and low-voltage-activated Ca 2+ currents.
Published Version
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