Fig. 4

Effect of chronic optogenetic stimulation of GABAergic neurons on Calcium overload in NTG and APP mice. (A) Diagram of AAV-CBA-YC3.6 construct. (B) Representative multiphoton images pseudocolored according to the intraneuronal calcium concentration in NTG and APP mice in absence of optogenetic stimulation (mCherry-no opto), in presence of optogenetic stimulation of mCherry (mCherry-opto) and optogenetic stimulation of ChR2 (ChR2-opto). Neuronal processes exhibiting calcium overload are shown in red (see arrowheads). (C) Histogram showing the distribution of YFP/CFP ratios in neurites expressing YC 3.6 of APP mice. (D) The percentage of neurites exhibiting calcium overload across conditions in APP mice. (E) Histogram showing the distribution of YFP/CFP ratios in neurites expressing YC 3.6 of NTG mice. (F) The percentage of neurites exhibiting calcium overload across conditions in NTG mice. All data are expressed as means ± standard error. Neuronal calcium overload was defined as a YFP/CFP ratio larger than 2 standard deviations above the average YFP/CFP ratio in the neurons of NTG mice. The ratio of YFP/CFP > 1.73 was considered calcium overload. The number of mice examined: n = 5–7 mice/group. ***P < 0.001. n.s. not significant. Scale bar: 50 μm