RECEPTOR ENDOCYTOSIS AND DENDRITE RESHAPING IN SPINAL NEURONS AFTER SOMATOSENSORY STIMULATION

In vivo somatosensory stimuli evoked the release of substance P from p rimary afferent neurons that terminate in the spinal cord and stimulat ed endocytosis of substance P receptors in rat spinal cord neurons. Th e distal dendrites that showed substance P receptor internalization un derwent morphological reorganization, changing from a tubular structur e to one characterized by swollen varicosities connected by thin segme nts. This internalization and dendritic structural reorganization prov ided a specific image of neurons activated by substance P. Thus recept or internalization can drive reversible structural changes in central nervous system neurons in vivo. Both of these processes may be involve d in neuronal plasticity.