Figure 7. Acute and chronic effects of CB1R-mediated actomyosin contraction on somatodendritic morphology.
(A) Cultured hippocampal neurons expressing CB1R-eCFP, LifeAct-mCherry, and EB3-eGFP at DIV8. Application of 100 nM WIN results in rapid and significant reorganization of somatodendritic morphology, characterized by retraction of distal dendritic parts (arrowheads), and broadening of the proximal part of dendrites (arrows). (A′) In dendrites, characteristic microtubule bending (arrowheads) and appearance of straight cable-like F-actin bundles (arrowheads) are accompanied by CB1R endocytosis after agonist activation (arrows). (B and C) Chronic inhibition of ROCK or NM II abolishes CB1R-activation induced changes structure of the cultured hippocampal neurons expressing Flag-CB1R-eGFP and the structural marker DsRed2 at DIV4. Cells were fixed at 24 hr after treatment with inhibitors of ROCK (Y-27632, 10 µM) or NM II (blebbistatin, 25 µM) in the presence of vehicle (VE) or CB1R agonist WIN (100 nM). A representative cell is shown for each condition. (C) Results are pooled from at least two independent experiments and are expressed as mean ± SEM. n.s p > 0.05; **p < 0.01, calculated using one-way ANOVA followed by Newman–Keuls post-tests. Scale bars: 20 µm on (A), 5 µm on (A′), and 50 µm on (B).