0068 Effect of Tongue Motor Task Training on Serotonergic Excitatory Drive to Genioglossus Electromyographic Activity in Rats. (27th April 2018)

• Record Type: Journal Article
• Authors: Li, W; Wang, W
• Is Part Of: Sleep. Volume 41(2018)Supplement 1
• Page Start: A28
• Page End: A28
• Publication Date: 2018-04-27
• Subjects: Sleep -- Physiological aspects -- Periodicals; Sleep disorders -- Periodicals; Sommeil -- Aspect physiologique -- Périodiques; Sommeil, Troubles du -- Périodiques; Sleep disorders; Sleep -- Physiological aspects; Sleep -- physiological aspects; Sleep Wake Disorders; Psychophysiology; Electronic journals; Periodicals; 616.8498
• DOI: 10.1093/sleep/zsy061.067
• Languages: English
• ISSNs: 0161-8105

Abstract

Abstract: Introduction: In obstructive sleep apnea (OSA) patients, hyperactivity of the tongue muscles protects the upper airway against occlusions during wakefulness. Tongue task training in human was associated with plasticity of corticomotor excitability of Genioglossus. Since rats subjected to tongue exercise revealed increased serotonergic input to the hypoglossal nucleus, this study aimed to investigate whether these anatomic indexes of increased serotonergic innervation could translate into increased sensitivity of genioglossus activity to serotonergic activation. Methods: 18 water-restricted adult male Sprague-Dawley rats were trained to lick an isometric force-sensing disc at targeting forces (30–50% maximal protrusion force) for water reinforcement with sound feedback. The rats in Tongue motor-oriented Task Training (TTT) group were trained daily for two month, and the training intensity was fixed by a total tongue muscle work of 1000 g·s per day. 24 hours after 8-weeks-training, rats were anesthetized, vagotomized and paralyzed. The dorsal medulla was exposed, and 5-HTP (5 mM, 20 nl) or 5-HT2A receptor antagonist ketanserin (1 mM, 3 x 40nl) were microinjected into the XII nucleus while genioglossus electromyographic (EMG) activity was recorded. The EMG-root mean square values was measured before and at different times after microinjections. Results: The excitatory effect of 5-HTP on the tonic genioglossus EMG activity was similar in sham- and TTT-treated rats within 20 minutes after injection, while this excitability maintained up to 40 minutes only in TTT-treated rats. In contrast, the tonic genioglossus EMG activity was more profoundly reduced 30 minutes following ketanserin injections in TTT- than sham-treated rats [36% ± 7% vs. 78 ± 11%, p < 0.05], without significant changes in central respiratory rate or heart rate. Conclusion: Consistent with increased neuroanatomic measures of serotonergic innervation of XII nucleus following tongue training, ketanserin microinjections revealed a stronger endogenous serotonergic excitatory drive to genioglossus activity in TTT- than sham-treated anesthetized rats. These results could have implications for treatment paradigms related to enhancement of central neuromuscular output of tongue for OSA patients. Support (If Any): Supported by Liaoning (China) Institutes of Innovation Team, Grant LT 2013015.