Retrograde regulation of neuronal size in the entorhinal cortex: consequences of the destruction of dentate gyrus granule cells with colchicine

Studies in developing animals have documented that manipulations which increase or decrease the size of a neuron's axon arbor lead to increases or decreases respectively in the size of the neuron's soma. The present study evaluates whether similar dependencies exist in adult animals, by analyzing changes in cell size in the entorhinal cortex after selective destruction of dentate granule cells with colchicine. Neurons in layer II of the entorhinal cortex which had been deprived of their normal targets decreased in size by 32% relative to their contralateral homologs. Neurons in layer III which project to regio superior of the hippocampus were affected to only a slight extent, decreasing in size by 8% relative to their contralateral homologs. Neurons in layer V, which do not project to the hippocampus, were unaffected by colchicine injections into the hippocampus. These results indicate that neurons in adult animals which retract terminal arbors as a consequence of target loss also decrease in size.