Fig. 4.

Enhancement of calcium transients by Aβ₄₂ peptides requires α7-nAChRs. A) Western blot of astrocyte cultures and adult mouse brain tissues. Lanes 1 and 2: purified astrocyte cultures, lane 3: cortex, lane 4: hippocampus. B) α7 nAChR subunit immunocytochemistry with purified astrocyte culture (red: α7 subunit, blue: DAPI nuclear stain). C) Live cell-surface labeling of hippocampal neuron (left) and astrocyte (right) cultures with Alexa Fluor 594-conjugated α-bungarotoxin. D) Frequency of spontaneous calcium transients. 200 pM Aβ peptides (freshly prepared) and/or MLA were applied at the beginning of the second (20 min) imaging block (arrow). Vehicle n = 16 (4554 cells), Aβ₄₂ 200 pM n = 18 (5241 cells), Aβ₄₂ 200 pM + MLA n = 13 (3929 cells), α7 knockout + Aβ₄₂ 200 pM n = 9 (2801 cells). E) Amplitude of spontaneous calcium transients. F) Summary of frequency data at the 30 and 40 min imaging blocks. G) Summary of the amplitude data at the 30 and 40 min imaging blocks. Data presented as means ± SEM, normalized as fold changes from the baseline control block. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001 compared to vehicle control by ANOVA.