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Sequential acquisition of cacophony calcium currents, sodium channels and voltage‐dependent potassium currents affects spike shape and dendrite growth during postembryonic maturation of an identified D rosophila motoneuron
Author(s) -
Ryglewski Stefanie,
Kilo Lukas,
Duch Carsten
Publication year - 2014
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12517
Subject(s) - dendrite (mathematics) , neuroscience , calcium , biophysics , potassium channel , biology , potassium , ion channel , microbiology and biotechnology , patch clamp , electrophysiology , chemistry , biochemistry , geometry , mathematics , receptor , organic chemistry
During metamorphosis the CNS undergoes profound changes to accommodate the switch from larval to adult behaviors. In D rosophila and other holometabolous insects, adult neurons differentiate either from respecified larval neurons, newly born neurons, or are born embryonically but remain developmentally arrested until differentiation during pupal life. This study addresses the latter in the identified D rosophila flight motoneuron 5. In situ patch‐clamp recordings, intracellular dye fills and immunocytochemistry address the interplay between dendritic shape, excitability and ionic current development. During pupal life, changes in excitability and spike shape correspond to a stereotyped, progressive appearance of voltage‐gated ion channels. High‐voltage‐activated calcium current is the first current to appear at pupal stage P4, prior to the onset of dendrite growth. This is followed by voltage‐gated sodium as well as transient potassium channel expression, when first dendrites grow, and sodium‐dependent action potentials can be evoked by somatic current injection. Sustained potassium current appears later than transient potassium current. During the early stages of rapid dendritic growth, sodium‐dependent action potentials are broadened by a calcium component. Narrowing of spike shape coincides with sequential increases in transient and sustained potassium currents during stages when dendritic growth ceases. Targeted RNA i knockdown of pupal calcium current significantly reduces dendritic growth. These data indicate that the stereotyped sequential acquisition of different voltage‐gated ion channels affects spike shape and excitability such that activity‐dependent calcium influx serves as a partner of genetic programs during critical stages of motoneuron dendrite growth.