Transmitter-evoked local calcium release stabilizes developing dendrites.
In the central nervous system, dendritic arborizations of neurons undergo dynamic structural remodelling during development. Processes are elaborated, maintained or eliminated to attain the adult pattern of synaptic connections. Although neuronal activity influences this remodelling, it is not known how activity exerts its effects. Here we show that neurotransmission-evoked calcium (Ca(2+)) release from intracellular stores stabilizes dendrites during the period of synapse formation. Using a ballistic labelling method to load cells with Ca(2+) indicator dyes, we simultaneously monitored dendritic activity and structure in the intact retina. Two distinct patterns of spontaneous Ca(2+) increases occurred in developing retinal ganglion cells--global increases throughout the arborization, and local 'flashes' of activity restricted to small dendritic segments. Blockade of local, but not global, activity caused rapid retraction of dendrites. This retraction was prevented locally by focal uncaging of caged Ca(2+) that triggered Ca(2+) release from internal stores. Thus, local Ca(2+) release is a mechanism by which afferent activity can selectively and differentially regulate dendritic structure across the developing arborization.
Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 S. Euclid, St Louis, Missouri 63110, USA.
Christian
C
Lohmann
Karen L
KL
Myhr
Rachel O L
RO
Wong
D000109:Acetylcholine / Q000494:pharmacology; D025042:Amacrine Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D048429:Cell Size / Q000187:drug effects; D002642:Chick Embryo; D003712:Dendrites / Q000187:drug effects* / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012433:Ryanodine / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D007211:Indoles; D018377:Neurotransmitter Agents; D018733:Nicotinic Antagonists; D012433:Ryanodine; C085112:2-nitrophenyl-EGTA; D013779:Tetrodotoxin; D004533:Egtazic Acid; D019284:Thapsigargin; D001285:Atropine; D000109:Acetylcholine; D002118:Calcium; C000543:cyclopiazonic acid