HMG-CoA reductase inhibitor induces a transient activation of high affinity nerve growth factor receptor, Trk, and morphological differentiation with fatal outcome in PC 12 cells

The present study was aimed at investigating the possible toxicity of simvastatin on a neuronal cell line, PC12 cells. Simvastatin clearly induced a transient morphological differentiation as evidenced by the occurrence of neurite outgrowth with a transient activation of the high affinity nerve growth factor receptor, Trk, but died at 36 h after its addition. Tyrosine autophosphorylation of the Trk protein also disappeared at 36 h after addition. During the morphological differentiation, NGF mRNA expression was upregulated transiently and returned to the basal level at 36 h after addition of simvastatin. These results suggest that simvastatin is neurotoxic and PC12 cells elicited a protective response, involving a transient activation of a Trk-mediated intracellular signal transduction pathway by an autocrine secretion of NGF, although these responses did not persist against pro-apoptotic signals and resulted in an apoptosis of the PC12 cells.