Suppression of the swallowing reflex by stimulation of the red nucleus

• Swallowing reflex was evoked by stimulation of superior laryngeal nerve.
• Electrical stimulation applied to the red nucleus suppressed swallowing reflex.
• Microinjection of glutamate into the red nucleus also suppressed swallowing reflex.
• The red nucleus is involved in the control of swallowing.

We study whether the red nucleus is involved in control of swallowing. The swallowing reflex was induced in anesthetized rats by repetitive electrical stimulation of the superior laryngeal nerve. The electromyographic activities of the mylohyoid and thyrohyoid muscles were recorded in order to identify the swallowing reflex. Repetitive electrical stimulation applied to the red nucleus reduced the number of swallows. The onset latency of the first swallow was increased during repetitive electrical stimulation applied to the magnocellular part of the red nucleus. Microinjection of monosodium glutamate into the red nucleus also reduced the number of swallows. The onset latency of the first swallow was increased after microinjection of monosodium glutamate into the magnocellular part of the red nucleus. These results imply that the red nucleus is involved in the control of swallowing.