Enhancement of Gustatory Neural Responses by Parasympathetic Nerve in the Frog
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The autonomic nervous system affects the gustatory responses in animals. Frog glossopharyngeal nerve (GPN) contains the parasympathetic nerve. We checked the effects of electrical stimulation (ES) of the parasympathetic nerves on the gustatory neural responses. The gustatory neural impulses of the GPNs were recorded using bipolar AgCl wires under normal blood circulation and integrated with a time constant of 1 s. Electrical stimuli were applied to the proximal side of the GPN with a pair of AgCl wires. The parasympathetic nerves of the GPN were strongly stimulated for 10 s with 6 V at 30 Hz before taste stimulation. The integrated neural responses to 0.5 M NaCl, 2.5 mM CaCl2, water, and 1 M sucrose were enhanced to 130–140% of the controls. On the other hand, the responses for 1 mM Q-HCl and 0.3 mM acetic acid were not changed by the preceding applied ES. After hexamethonium (a blocker of nicotinic ACh receptor) was intravenously injected, ES of the parasympathetic nerve did not modulate the responses for all six taste stimuli. The mechanism for enhancement of the gustatory neural responses is discussed.
KeywordsBullfrog Gustatory neural response Parasympathetic nerve Glossopharyngeal nerve Electrical stimulation Neural modulation
This work was supported by school running expense from Nagasaki University.
Compliance with Ethical Standards
Conflict of interest
The authors do not have any conflict of interest.
All applicable institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
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