Fig. 3.

Glutamate release and activation of JNK and p38 were not affected by low-frequency stimulation. A, Mean EPSP slope was unchanged by stimulation at a rate of one shock per 12 sec for a 50 min recording period, whereas tetanic stimulation increased mean EPSP slope. B, Addition of KCl significantly increased glutamate release in synaptosomes prepared from dentate gyrus of rats that received low-frequency stimulation (both sides; p < 0.05; ANOVA) and from the untetanized (p < 0.05; ANOVA) and tetanized (p < 0.01; ANOVA) tissue of rats that received tetanic stimulation. C, D, Activation of JNK and p38 were similar in all preparations. Values are means (± SEM) of four separate experiments for JNK and three for p38.