Neuroprotective and neuroregenerative effects of nimodipine in a model system of neuronal differentiation and neurite outgrowth.

Nimodipine is a Ca2+-channel antagonist mainly used for the management of aneurysmal subarachnoid hemorrhage (aSAH) to prevent cerebral vasospasms. However, it is not clear if the better outcome of nimodipine-treated patients is mainly due to vasodilatation or whether other cellular neuroprotective or neuregenerative effects of nimodipine are involved. We analysed PC12 cells after different stress stimuli with or without nimodipine pretreatment. Cytotoxicity of 200 mM EtOH and osmotic stress (450 mosmol/L) was significantly reduced with nimodipine pretreatment, while nimodipine has no influence on the hypoxia-induced cytotoxicity in PC12 cells. The presence of nimodipine also increased the NGF-induced neurite outgrowth in PC12 cells. However, nimodipine alone was not able to induce neurite outgrowth in PC12 cells. These results support the idea that nimodipine has general neuroprotective or neuregenerative effect beside its role in vasodilatation and is maybe useful also in other clinical applications beside aSAH.

Phosphorylation of serine 774 of the neural cell adhesion molecule is necessary for cyclic adenosine monophosphate response element binding protein activation and neurite outgrowth.

The neural cell adhesion molecule (NCAM) plays a fundamental role during development and regeneration. NCAM is expressed in three major isoforms, two of them with intracellular domains of different length and one without any intracellular domain. The cytoplasmic domain of NCAM contains, depending on the isoform, up to 49 phosphorylation sites, and it has been demonstrated previously by phosphoproteomic analysis that NCAM is phosphorylated on serine 774. However, the impact of NCAM phosphorylation is unclear. Here we have analyzed the phosphorylation of serine 774 in more detail and found that phosphorylation of this site is crucial for NCAM-mediated signal transduction. A serine-to-alanine exchange at position 774 (NCAM140-S774A) resulted in decreased activation of the cAMP response element binding protein (CREB) after NCAM stimulation and, as a consequence, in decreased neurite outgrowth of NCAM140-S774A-transfected B35 neuroblastoma cells.