Fig. 2. Tetanic stimulation induces nuclear translocation of PYK2 in hippocampal slices. (A) Mouse hippocampal slices were incubated in physiological ACSF (Control) or treated with high [K⁺]_o (High K⁺) as in Fig. 1, or subjected to a tetanic stimulation of the stratum radiatum (Schaeffer collaterals, 100 Hz, 4x 1 second, at 10-second intervals). Slices were prepared as in Fig. 1 and stained with an anti-PYK2 antibody or a phospho-specific antibody directed against pY402-PYK2. The CA1 region was analyzed by confocal microscopy (single optical sections are shown). Bars, 10 µm. (B) Quantification of the cells in which anti-PYK2 immunostaining in the nucleus (nuclear PYK2) was equal to or greater than in the cytoplasm. Values are means ± s.e.m., 12 slices per group, one-way ANOVA: F_(2,33)=11.2, P<0.001. Newman-Keuls test: ^**P<0.01, ^***P<0.001. (C) Tetanic stimulation of excitatory CA3-to-CA1 synapses potentiated synaptic transmission. Graph shows an example from one of the radiatum pathways. The slopes of the elicited field EPSPs were normalized to the mean value obtained 1 minute prior to tetanization (solid arrows). The slice was removed from the recording chamber 5 minutes after the repeated tetanization procedure and fixed. Inset: superimposed synaptic responses at times indicated by open arrows and numbers.