Potentiation of quantal secretion by insulin-like growth factor-1 at developing motoneurons in Xenopus cell culture.

Although evidence suggests that insulin-like growth factor (IGF) plays an important role in the development and growth of the nervous system, the effect of IGF-1 in the regulation of neurotransmitter release in the peripheral nervous system remains unknown. Here we show that acute application of IGF-1, a factor widely expressed in developing myocytes, dose-dependently enhances the spontaneous acetylcholine (ACh) secretion at developing neuromuscular synapses in Xenopus cell culture using whole-cell patch clamp recording. We studied the role of endogenously released IGF-1 by examining the effect of IGF-1 antibody on the frequency of spontaneous synaptic currents (SSCs) at high-activity synapses, and found SSC frequency was markedly reduced at these high-activity synapses.