Neuroscience 2003 Abstract
| Presentation Number: | 499.11 |
|---|---|
| Abstract Title: | Developmental downregulation of ATP receptors in esophageal motoneurons (MNs). |
| Authors: |
Brosenitsch, T. A.*1
; Lipski, J.1
; Housley, G. D.1
; Funk, G. D.1
1Dept. Physiology, Univ. Auckland, Auckland, New Zealand |
| Primary Theme and Topics |
Motor Systems - Brainstem -- Physiology |
| Secondary Theme and Topics | Synaptic Transmission and Excitability<br />- Ligand Gated Ion Channels<br />-- Purine receptors |
| Session: |
499. Brainstem II Poster |
| Presentation Time: | Monday, November 10, 2003 3:00 PM-4:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # I3 |
| Keywords: | motor control, nucleus ambiguus, development, P2 receptor |
Adenosine Triphosphate (ATP), acting via ionotropic (P2X) and metabotropic (P2Y) receptors, is well established as a neurotransmitter in sensory systems. It is also involved in modulating rhythmic motor behaviors (eg. locomotion, respiration) through actions on central rhythm generating circuits (Dale & Gilday, 1996 Nature 383 p259; Lorier et al, 2002 SFN Abst 173.8 ) and MNs (Miles et al, 2002 J Appl Physiol 92 p1899). To further explore the role of ATP signaling in motor control, we used whole-cell recording techniques to characterize, during postnatal development, the effects of ATP on esophageal MNs of the compact formation of nucleus Ambiguus (cNA), the final output cells for the swallowing central pattern generator. Medullary slices containing the cNA were prepared from neonatal (P0-4) and juvenile (P15-21) rats. In a majority of neonatal cNA MNs (58/78 cells), local application of 1mM ATP produced a large (-180±20 pA), desensitizing (τ=6.2±0.4 ms), PPADS-sensitive (10µM, n=4) inward current that was mimicked by 1mM α,β-meATP (n=25). These data are consistent with expression of heteromeric receptors containing P2X1, X2, X3 or X5 subunits. In juvenile cNA MNs, on the other hand, 1mM ATP had minimal effect (-9±3 pA, n=18), and 10mM ATP produced only small (-32±3 pA), primarily non-desensitizing currents (37/42 cells). To define which P2X receptor subtypes might contribute to the ATP-evoked currents, expression of P2X1-6 receptor subunits was assessed immunochemically. In the neonate, expression of P2X3 was robust, P2X2,4,5,6 moderate, and P2X1 undetectable. In the juvenile cNA, only P2X6 was detected at low levels. These data indicate that expression of P2X receptor subunits in cNA MNs is profoundly downregulated during the first two postnatal weeks, and suggest an important role for the purinoceptor system in controlling the excitability, or development, of esophageal motor networks during early postnatal life.
Supported by HRC, AMRF, NZNF, CIHR, AHFMR and CFI.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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