Glycine changes the sequential pattern of swallowing activity in the working heart–brainstem preparation in rats

Abstract

Abstract Swallowing is a centrally programmed intricate activity consisting of both excitatory and inhibitory neural transmissions to ensure aspiration does not occur. However, the central mechanisms involved, in particular, the role of the inhibitory transmission underlying the establishment of sequential movements, are not well understood. Recently, some studies have demonstrated swallowing activity recorded from the working heart–brainstem preparation (WHBP), a useful model utilized to study the neuronal mechanisms involved in centrally controlled functions. However, such an activity has not yet been adequately confirmed. The aims of this study were first to confirm ability of WHBP to elicit swallowing activity, then study the roles of inhibitory neurotransmitter receptors in the sequential swallowing activity. Then, we found that application of a glycine receptor antagonist accelerate the timing of muscle activation of the middle pharyngeal constrictor muscle during the sequential activity of swallowing, while application of a GABAA receptor antagonist did not. Based on these results, we concluded that WHBP has a conserved neuronal network necessary for establishing swallowing activity, and that glycine receptors played a role in the orchestration of the sequential pattern.