Atomic force microscopic observation of three-dimensional morphological changes of neurons where stimulated by a neurotransmitter

As the first step in the study df morphological changes in neurons associat ed with their functional changes, we applied atomic force microscopy (AFM) for the observation of fine three-dimensional morphological changes in rat cerebellar granule cells stimulated by an agonist of glutamate receptors, N -methyl-D-aspartate (NMDA). The AFM revealed that NMDA changed the cross-se ctions of cell bodies from a trapezoid-like form to a triangle-like form wi thin a minute. The fine hill-like structures on the top surfaces of the cel l bodies became wider during the same period. These results were suggested to be induced by the depolymerization; of filamentous actin triggered by th e entry of Ca2+ via cation channels complexed with the activated NMDA recep tors.