(A) Circular and longitudinal muscle contractile force was determined after various intensities of electric field stimulation (0.5, 1, 5, and 10 Hz). In all regions evaluated, contractility was stronger in GFAP-Gdnf than in WT mice at 5 or 10 Hz stimulation. (B, C) Electric field stimulation results in increased neurotransmitter release for VIP (B) and substance P (C) in both WT and GFAP-Gdnf mice. The increase in transmitter release is greater in GFAP-Gdnf than in WT animals. N = 4 mice of each genotype. Error bars represent ± SEM. * P < 0.05 for GFAP-Gdnf versus WT mice at each electric field strength.