Mastication stimuli regulate the heartbeat rate through rhythmic regulation by the hypothalamic-autonomic system; molecular and telemetric studies in weaning-stage rats

Seonmi Lee; Ryota Tochinai; Akihito Yasuoka; Toshitada Nagai; Yoshikazu Saito; Masayoshi Kuwahara; Keiko Abe; Tomiko Asakura

doi:10.3389/fnins.2023.1260655

Mastication stimuli regulate the heartbeat rate through rhythmic regulation by the hypothalamic-autonomic system; molecular and telemetric studies in weaning-stage rats

Front Neurosci. 2023 Sep 14:17:1260655. doi: 10.3389/fnins.2023.1260655. eCollection 2023.

Authors

Seonmi Lee¹, Ryota Tochinai², Akihito Yasuoka^{1

3}, Toshitada Nagai⁴, Yoshikazu Saito^{1

5}, Masayoshi Kuwahara², Keiko Abe^{1

6}, Tomiko Asakura¹

Affiliations

¹ Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
² Department of Veterinary Pathophysiology and Animal Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
³ Department of Human Nutrition, Seitoku University, Chiba, Japan.
⁴ Department of Applied Biological Science, Faculty of Agriculture, Takasaki University of Health and Welfare, Gunma, Japan.
⁵ Toyo Institute of Food Technology, Hyogo, Japan.
⁶ Project on Health and Anti-Aging, Kanagawa Academy of Science and Technology, Life Science and Environment Research Center (LiSE), Kawasaki, Japan.

Abstract

Mastication stimuli have been demonstrated to affect memory function and autonomic nerve activity; however, this process has not been well studied during weaning compared to old age. Previously, we conducted molecular analyses of the thalamus and hippocampus to elucidate the mechanisms underlying this memory-enhancing effect in weaning-stage rats. In this study, we aimed to evaluate the effect of masticatory stimuli on the regulation of heartbeat rate (HR) through the hypothalamic-autonomic system. Three-week-old male rats were administered a powdered diet (P group) or chow-diet (C group) for 10 days. Thereafter, transcriptome analysis was performed. Vasopressin, cocaine-amphetamine-regulated transcript prepropeptide, corticotropin-releasing hormone, and thyrotropin-releasing hormone, which are involved in sympathetic activation of heart rate, were downregulated in the C group. Electrocardiograms were recorded continuously for 12 days under the same condition. Interestingly, rats in the C group had a significantly lower HR than those in the P group on day 11. We checked several parameters representing the autonomic regulation of HR. The C group had higher values for the high-frequency band integration of the HR power spectrum (parasympathetic marker) and root mean square successive difference of R-wave intervals (parasympathetic marker) relative to the P group. Such findings provide a molecular and physiological basis for understanding the regulation of cardiovascular function in response to masticatory stimuli in the autonomic nervous system.

Keywords: autonomic nerve; heartbeat rate; hypothalamus; mastication; transcriptome; weaning.