Figure 4: Two-photon calcium imaging in primary afferent terminals.
From: Presynaptic GABAergic inhibition regulated by BDNF contributes to neuropathic pain induction
(a) Scheme illustrating the specific expression pattern of GCaMP3 in primary sensory neurons. (b) Bright-field picture of spinal cord slice used for two-photon imaging. (c–n) Two-photon images from control, injured and BDNF-treated mouse spinal cord slice were showed in first (c–f), second (g–j) and third row (k–n), respectively. (o,q,s) Relative GCaMP3 fluorescence changes (ΔF/F) during high KCl, GABA alone and GABA+KCl in afferent terminals are shown as colour maps. (p,r,t) Traces showing the relative change of GCaMP3 fluorescence during high KCl, GABA and GABA+KCl in example ROIs from control (p), injured (r) and BDNF (t)-treated mouse spinal cord slice. (u) Fraction of ROIs responded to GABA application from separate experiments (control: n=4; injury, n=5; BDNF, n=6). Error bars indicate s.e.m. (v) and (w) Frequency histograms of the proportion of three different effects of GABA on high KCl-induced GCaMP3 fluorescence increase. (v) The proportion from all ROIs pooled from all experiments. The number of ROIs recorded is indicated in parentheses in each panel. (Control versus injury, χ2-test, P<0.0001; control versus BDNF, χ2-test, P<0.0001). Error bars indicate s.e.m. Error bars in w represents the s.e.m. of the proportion of ROIs from separate experiments (experiment number: control, n=5; injury, n=6; BDNF, n=7; inhibitory effect: control versus injury, unpaired t-test, P<0.05; control versus BDNF, unpaired t-test, P<0.05. excitatory effect: control versus injury, unpaired t-test, P>0.05; control versus BDNF, unpaired t-test, P>0.05). Scale bars, (b) 200 μm; (c–n) 10 μm; (scale bar only shown in b and n). *P<0.05; ***P<0.001.
