Activation of Intra-nodose Ganglion P2X7 Receptors Elicit Increases in Neuronal Activity
Alcayaga, Julio
Universidad de Chile
Vera, Jorge
Universidad de Chile
Reyna-Jeldes, Mauricio
Universidad Catolica del Norte
Covarrubias, Alejandra A. A.
Universidad Catolica del Norte
Coddou, Claudio
Universidad Catolica del Norte
Diaz-Jara, Esteban
Pontificia Universidad Catolica de Chile
Retamal, Mauricio A. A.
Universidad del Desarrollo
Journal
Cellular and Molecular Neurobiology
ISSN
0272-4340
1573-6830
Open Access
green
Volume
43
Start page
2801
End page
2813
Vagus nerve innervates several organs including the heart, stomach, and pancreas among others. Somas of sensory neurons that project through the vagal nerve are located in the nodose ganglion. The presence of purinergic receptors has been reported in neurons and satellite glial cells in several sensory ganglia. In the nodose ganglion, calcium depletion-induced increases in neuron activity can be partly reversed by P2X7 blockers applied directly into the ganglion. The later suggest a possible role of P2X7 receptors in the modulation of neuronal activity within this sensory ganglion. We aimed to characterize the response to P2X7 activation in nodose ganglion neurons under physiological conditions. Using an ex vivo preparation for electrophysiological recordings of the neural discharges of nodose ganglion neurons, we found that treatments with ATP induce transient neuronal activity increases. Also, we found a concentration-dependent increase in neural activity in response to Bz-ATP (ED50 = 0.62 mM, a selective P2X7 receptor agonist), with a clear desensitization pattern when applied every similar to 30 s. Electrophysiological recordings from isolated nodose ganglion neurons reveal no differences in the responses to Bz-ATP and ATP. Finally, we showed that the P2X7 receptor was expressed in the rat nodose ganglion, both in neurons and satellite glial cells. Additionally, a P2X7 receptor negative allosteric modulator decreased the duration of Bz-ATP-induced maximal responses without affecting their amplitude. Our results show the presence of functional P2X7 receptors under physiological conditions within the nodose ganglion of the rat, and suggest that ATP modulation of nodose ganglion activity may be in part mediated by the activation of P2X7 receptors.
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