The objectives of this study were to describe the size distribution of capsaicin-sensitive neurons in nodose and jugular ganglia and to determine whether there is a difference in capsaicin sensitivity between these two types of ganglia. Functional identification was made by measurement of the capsaicin-evoked calcium (Ca2+) transients in cultured vagal sensory neurons of young adult Sprague-Dawley rats using the Fura-2-based ratiometric imaging technique. In the first study series, cells on the second day of culture were perfused with capsaicin solution (10-7 M) for 15 s, and the Ca2+ transients were continuously recorded before, during, and after the capsaicin challenge. Out of 603 viable neurons, 57.5% were capsaicin-sensitive; the percentages of capsaicin-sensitive cells in the nodose and jugular ganglia were 59.8% and 55.4%, respectively. Capsaicin sensitivity predominated in the small- and medium-sized neurons; the capsaicin-sensitive cells generally had a diameter less than 35 μm in both types of ganglia. Although the results did not indicate any differences in the size distribution of capsaicin-sensitive neurons between the two ganglia, results of our second study series showed that a near-maximal concentration of capsaicin (3×10-6 M) evoked a significantly greater peak Ca2+ transient in jugular neurons (382.5±85.5 nM) than in nodose neurons (134.3±17.5 nM). In summary, our results showed that an increase in cell diameter was accompanied by a decreasing trend in percentage of capsaicin-sensitive neurons in both vagal ganglia. Capsaicin at high concentration evoked a greater peak Ca2+ transient in jugular ganglion neurons, despite no difference in the responses to KCl between these two types of ganglion neurons.
|Number of pages||6|
|Journal||Autonomic Neuroscience: Basic and Clinical|
|State||Published - May 31 2002|
Bibliographical noteFunding Information:
We are grateful to Dr. Stuart Bevan and Dr. Linda Mclatchie at the Novartis Institute for Medical Sciences, London, UK for their generous guidance and assistance in the early stage of this study. We also thank Ruth Oremus, Jennifer Kasten, Helen Liu, and Melenia Poonacha for their technical assistance. This study was supported by grants from National Institutes of Health (HL 58686, TW 01734).
- Fura-2 dual-excitation imaging
- VR1 receptor
- Vagal sensory neurons
ASJC Scopus subject areas
- Endocrine and Autonomic Systems
- Clinical Neurology
- Cellular and Molecular Neuroscience