Figure 8.
IGF-1 potentiates GlyR current by increasing the agonist apparent affinity. A, Effect of IGF-1 (50 ng/ml) on the currents evoked by three increasing concentrations of taurine, at a holding potential of -46 mV. The magnitude of the potentiation depended on the agonist concentration, and IGF-1 had little effect at near-saturating doses of taurine. Recordings were performed in the presence of 3 μm gabazine to prevent activation of GABAA receptors by high concentrations of taurine. B, Dose-response curves for taurine in the absence and presence of IGF-1. All current amplitudes were normalized to the maximal amplitude estimated in the absence of IGF-1. IGF-1 shifts the curve to the left with no change in the maximal amplitude. Each point is the average obtained from 5 to 11 cells.