Figure 4: Excitatory N398 neurons exhibit increased response to nicotine followed by desensitization.
From: Increased nicotine response in iPSC-derived human neurons carrying the CHRNA5 N398 allele
(A) Glutamatergic iN cultures are positive for MAP2 (green), vesicular glutamate transporter 1 (VGluT1, left, red), and synapsin (Syn, right, red) as detected by ICC. (B) Example traces from a patched neuron to show changes in response upon introduction of 0.1 μM nicotine (indicated by bar). Patched neurons exhibited increased frequency (C) and amplitude (D) during initial exposure to 0.1 μM nicotine. By 60 s after nicotine addition, frequency trended lower in N398 cells, although not significantly. Plotting the initial response to 0.1 μM nicotine for individual cells, it is clear that the changes in frequency (E) or amplitude (F) in N398 was not due to a single cell or subject. D398 samples are plotted as circles and N398 as squares. Color denotes cells from individual subjects (see key and Supplemental Table 1). However, subsequent additions of increasing doses of nicotine had reduced initial frequency (G) and amplitude (H) in N398 compared with D398 cells. N398 was different in frequency response from D398 as assessed by a Tukey post-hoc test of a general linear mixed-effects model with repeated measures (p = 0.00046, n = 115 cells per genotype; 5 cells per culture; 5–7 cultures per individual cell line).
