Effects of Extremely Low Frequency Magnetic Field on Neurite Outgrowth of PC12 and PC12D Cells and Evaluation by Image Analysis

A pheochromocytoma cell (PC12), and its derivative (PC12D), differentiate to nervelike cells in culture with the nerve growth factor (NGF) and forskolin respectively. We introduced a morphological factor σ= L /2(π A ) 1/2 for quantitating neurite outgrowth under a microscope in the presence of extremely low-frequency (ELF) magnetic fields for 22 hours, where L and A are the contour length and the area of the cells in clump determined using an image-analysis system. ELF magnetic fields B 1 were generated with a single coil or double coils in Helmholtz configuration together with static fields B 0 of -53, -20 and 67 µT. σ increased with increasing NGF or forskolin level at B 0 =-53 µT (geomagnetism), in agreement with the cytometric observation of micrographs. With the addition of an AC field B 1 at 60 Hz (100 µT > B 1 > 3 µT rms) to B 0 , neurite outgrowth represented by σ was depressed for PC12 and stimulated for PC12D. We discuss the cyclotron resonance and the ion parametric resonance models.