Figure 7.

Doxycycline (DOX) treatment (1 week) reverses the synaptic phenotype in Tg1/Tg2 mice. a, b, Electron micrographs illustrating axon terminals and synaptic contacts (arrows) in the IML of Tg1/Tg2 (a) and DOX-treated Tg1/Tg2 (b) mice. Note that the complexity of synaptic boutons and dendritic spines in transgenic mice is reversed upon DOX treatment. c, d, The density of synaptic contacts (c) and the percentage of synaptic terminals establishing at least two contacts (d) are reversed in Tg1/Tg2 mice treated with doxycycline. e, DOX treatment of Tg1/Tg2 mice leads to a marked reduction in the density of dendritic spines receiving at least one synaptic contact, reaching values lower than those observed in control mice. at, Axon terminal. Data are presented as mean ± SEM; *p < 0.05; **p < 0.01; ***p < 0.001; Student's t test. Scale bars: a, b, 0.5 μm.