Skip to main content
. 2008 Feb 13;28(7):1733–1744. doi: 10.1523/JNEUROSCI.5130-07.2008

Figure 7.

Figure 7.

Transient interruption in nerve growth factor signaling increases cytosolic ROS and causes rundown of ACh evoked currents. A, Phase micrographs of sympathetic neurons in culture for 2 weeks. NGF was removed for 18 h (top) or 48 h (bottom). The micrographs were taken at 18 h after removing NGF (left) and the same field retaken 5 d (right) after replacing NGF. The insets are magnified images of the cell bodies in each field. After 18 h without NGF followed by 5 d with NGF, the neurons have phase-bright nuclei, clearly visible nucleoli; however, after 48 h without NGF, the neurons are in poorer health. B, ΔF/F measurements from sympathetic neurons before and after being deprived of NGF for 2, 6, 18, and 48 h (>50 neurons were measured at each time point). Neurons were loaded with CM-H2DCFDA for 1 h and then imaged. The fluorescence remained near basal levels for the first 6 h; after 18 h of NGF removal, the increase in ΔF/F was comparable with that induced by ROS from the Fenton reaction or antimycin-A (dotted line). The solid line is a Hill function. C, Number of neurons per culture before (CTL) (n = 80) and 5 d after a transient removal of NGF for 18 h (n = 150), 24 h (n = 53), or 48–72 h (n = 109). A transient interruption in NGF signaling for 18 h had no significant effect on neuronal survival. D–F, ACh-evoked currents in response to a series of 1 s ACh (100 μm) applications delivered at 15 s intervals from a control (+NGF) neonatal mouse SCG neuron (D) in culture for 10 d, one in a sister culture deprived of NGF for 18 h (E), and one in a sister culture deprived of NGF for 18 h but pretreated with antioxidants (DHA) for 24 h at 6 h before NGF removal (F). G, I30/I1 ratio for neurons from control (CTL) (n = 7), 18 h after NGF removal (−NGF) (n = 14), 18 h after NGF removal with antioxidants (−NGF + DHA) (n = 6), and 1 week after a transient 18 h NGF withdrawal (n = 6). The SEs are too small to resolve. H, Bar graph showing the ratio of the peak INa and IK (mean ± SE; n = 7) before and after rundown of the ACh-evoked currents on neurons 18 h after removal of NGF. There was no significant difference in the peak INa or IK before and after rundown of the ACh-evoked currents. ***p < 0.001.