Insulin-like growth factor 1 stimulates the release of acetylcholine from rat cortical slices

The effect of somatomedin, or insulin-like growth factors (IGF-1 and IGF-2), on the basal and potassium induced release of 3H]acetylcholine (3H]Ach) from rat cortical slices, previously preincubated with 3H]choline (3H]Ch), was studied in vitro. IGF-1 (1.4 x 10(-9) to 1.4 x 10(-8) M) had no effect on the basal release of 3H]ACh, while IGF-1 (1.4 x 10(-9) to 4.3 x 10(-8) M) increased the potassium induced release of 3H]ACh from rat brain slices in a concentration-dependent manner. However IGF-2 (1.4 x 10(-8) M) had no effect. Insulin (1.8 x 10(-8) to 5.3 x 10(-8) M), similarly, did not have any influence on the release of 3H]ACh, demonstrating that the facilitatory effect of IGF-1 on 3H]ACh release is not mediated via insulin receptors. This report demonstrates for the first time that IGF-1 has an effect on neurotransmission in the adult brain.