Figure 1. Learning induces biphasic changes in stathmin activity and microtubule stability.
(a) Immunoblot estimation of stathmin phosphorylation at Ser16 (pS16), Ser25 (pS25), and Ser38 (pS38) 0.5, 1, 2, 8, or 24 h following contextual fear conditioning. N, naïve. n = 6 per group (pooled tissues from 3–4 mice per sample). *p < 0.05 versus naïve mice (post hoc comparison). (b) Analysis of stathmin-tubulin protein interactions using co-immunoprecipitation. Stathmin-tubulin complexes are formed at 0.5 h and dissociate at 8 h after contextual fear conditioning. n = 4 per group (pooled tissues from 4–5 mice per sample). *p < 0.05 (post hoc comparison). (c) Immunoblot estimation of detyrosinated (Detyr-) and tyrosinated (Tyr-) α-tubulin levels after contextual fear conditioning. n = 6 per group (pooled tissues from 3–4 mice per sample). *p < 0.05 versus naïve mice (post hoc comparison). (d) Experimental design for drug administration 8 h following contextual fear conditioning. Memory was tested 24 h after training. (e) Mice injected with nocodazole 8 h following training show reduced freezing. vehicle, n = 11; nocodazole, n = 12. *p < 0.05 (Student’s t test). (f) Mice injected with paclitaxel 8 h following training show increased freezing. vehicle, n = 11; nocodazole, n = 12. *p < 0.05 (Student’s t test). Data are expressed as mean ± s.e.m.