Dataset Information

Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions.

ABSTRACT:

Background

Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs).

Methods

To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-type VGNs at different developmental stages using whole-cell patch clamping.

Results

C-type VGNs underwent significant age-dependent transition from single action potential (AP) to repetitive discharge. The coordinate changes between TTX-S and TTX-R Na(+) currents were also confirmed and well simulated by computer modeling. Although 4-AP or iberiotoxin age dependently increased firing frequency, AP duration was prolonged in an opposite fashion, which paralleled well with postnatal changes in 4-AP- and iberiotoxin-sensitive K(+) current activity, whereas less developmental changes were verified in A-types.

Conclusion

These data demonstrate for the first time that the neuroexcitability of C-type VGNs increases significantly compared with A-types within initial postnatal weeks evidenced by AP discharge profiles and coordinate ion channel changes, which explain, at least in part, that initial postnatal weeks may be crucial for ontogenesis in visceral afferent reflex function.

SUBMITTER: Qian Z

PROVIDER: S-EPMC6493600 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Publications

Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions.

Qian Zhao Z Liu Dong-Jie DJ Liu Yang Y Han Li-Min LM Yuan Mei M Li Jun-Nan JN Xu Bing B Lu Xiao-Long XL Cao Pan-Xiang PX Wang Hao-Yan HY Pan Xiao-Dong XD Wang Li-Juan LJ Qiao Guo-Fen GF Li Bai-Yan BY

CNS neuroscience & therapeutics 20131025 12

<h4>Background</h4>Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs).<h4>Methods</h4>To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-typ ...[more]

PMID: 24164691

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Project description:Background & aimsProper colon function requires signals from extrinsic primary afferent neurons (ExPANs) located in spinal ganglia. Most ExPANs express the vanilloid receptor TRPV1, and a dense plexus of TRPV1-positive fibers is found around myenteric neurons. Capsaicin, a TRPV1 agonist, can initiate activity in myenteric neurons and produce muscle contraction. ExPANs might therefore form motility-regulating synapses onto myenteric neurons. ExPANs mediate visceral pain, and myenteric neurons mediate colon motility, so we investigated communication between ExPANs and myenteric neurons and the circuits by which ExPANs modulate colon function.MethodsIn live mice and colon tissues that express a transgene encoding the calcium indicator GCaMP, we visualized levels of activity in myenteric neurons during smooth muscle contractions induced by application of capsaicin, direct colon stimulation, stimulation of ExPANs, or stimulation of preganglionic parasympathetic neuron (PPN) axons. To localize central targets of ExPANs, we optogenetically activated TRPV1-expressing ExPANs in live mice and then quantified Fos immunoreactivity to identify activated spinal neurons.ResultsFocal electrical stimulation of mouse colon produced phased-locked calcium signals in myenteric neurons and produced colon contractions. Stimulation of the L6 ventral root, which contains PPN axons, also produced myenteric activation and contractions that were comparable to those of direct colon stimulation. Surprisingly, capsaicin application to the isolated L6 dorsal root ganglia, which produced robust calcium signals in neurons throughout the ganglion, did not activate myenteric neurons. Electrical activation of the ganglia, which activated even more neurons than capsaicin, did not produce myenteric activation or contractions unless the spinal cord was intact, indicating that a complete afferent-to-efferent (PPN) circuit was necessary for ExPANs to regulate myenteric neurons. In TRPV1-channel rhodopsin-2 mice, light activation of ExPANs induced a pain-like visceromotor response and expression of Fos in spinal PPN neurons.ConclusionsIn mice, ExPANs regulate myenteric neuron activity and smooth muscle contraction via a parasympathetic spinal circuit, linking sensation and pain to motility.

Dataset Information

Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions.

Background

Methods

Results

Conclusion

Publications

Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions.

Similar Datasets

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