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Updated: Jun 13, 2026

Fluorescent Calcium Imaging and Subsequent In Situ Hybridization for Neuronal Precursor Characterization in Xenopus laevis
Published on: February 18, 2020
Target-dependent regulation of neurotransmitter specification and embryonic neuronal calcium spike activity
Qian Xiao1, Lin Xu, Nicholas C Spitzer
1Neurobiology Section, Division of Biological Sciences, Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, California 92093-0357, USA. qxiao@ucsd.edu
Abstract:
Neurotransmitter specification has been shown to depend on genetic programs and electrical activity; however, target-dependent regulation also plays important roles in neuronal development. We have investigated the impact of muscle targets on transmitter specification in Xenopus spinal neurons using a neuron-muscle coculture system. We find that neuron-muscle contact reduces the number of neurons expressing the noncholinergic transmitters GABA, glycine, and glutamate, while having no effect on the incidence of ChAT expression. We show that muscle activity is necessary for target-dependent reduction of noncholinergic transmitter expression. In addition, we demonstrate that coculture with muscle cells suppresses early spontaneous calcium spike activity in neurons and the presence of muscle cells abolishes activity-dependent transmitter specification. The results indicate that target-dependent regulation can be crucial in establishing neurotransmitter phenotypes and altering early neuronal excitability.
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