Figure 6

ATP-derived adenosine contributes to status epilepticus-induced hippocampal mossy fiber sprouting. (a) The evoked presynaptic release of ATP induced by a K⁺-induced depolarization (KCl 30 mM) of purified hippocampal nerve terminals prepared from animals that experienced status epilepticus (SE) was analyzed at 24 h, 3 days and 7 days upon SE induction. Only animals reaching at least stage 4 seizures were considered. Convulsions were suppressed with diazepam (10 mg/kg, i.p.) 2 h after the occurrence of the first stage 4 seizure. While at 24 h and 3 days after SE induction, it was not observed any significant differences, the evoked release of ATP from hippocampal synaptosomes prepared 7 days after SE was significantly higher vs. control rats. Data are mean ± SEM of the percentage of modification in extracellular levels of ATP (time-course graphs) or of the area under the curve (histogram). Control (24 h), n = 5; SE (24 h), n = 5; Control (3 days), n = 5; SE (3 days), n = 7; Control (7 days), n = 5; SE (7 days), n = 5. The data are mean ± SEM of the percentage of modification in extracellular levels of ATP relative to basal levels. ***P < 0.001, one-way ANOVA with Sidak’s test. (b) Latency onset and seizure score during SE of wild-type mice and CD73-KO mice. Data are mean ± SEM. (c) Wild-type mice that had experienced SE displayed a dense Timm staining in the inner molecular layer of the dentate gyrus 105 days later, whereas in CD73-KO mice SE induced a significantly lower Timm staining, as depicted in the representative images (scale bar, 300µm) and quantitatively summarized in the (d) upper histogram. (e) The lower SE-induced mossy fiber sprouting in CD73-KO mice was observed along the entire septotemporal axis of the DG. The data are mean ± SEM of the percentage of the granule cell layer (GCL) plus molecular layer (ML) that displayed Timm staining. Control-wild-type, n = 4; Control-CD73 KO, n = 3; SE-wild-type, n = 6; SE-CD73 KO, n = 4. *P < 0.05 and ***P < 0.001 for SE vs. Control either in wild-type or in CD73-KO mice; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 for CD73-KO vs. wild-type mice either experiencing SE or not; two-way ANOVA with Sidak’s test.