Studies of the nervous control of blood flow to the orofacial area have revealed the presence of parasympathetic vasodilator fibers in orofacial tissues, such as epithelial tissues, muscles, and salivary glands. Trigeminal afferent inputs reflexively induce activation of these parasympathetic vasodilator fibers, and lead to rapid and marked increases in blood flow in these tissues. Therefore, parasympathetic vasodilation induced by this trigeminal mediated reflex may be involved in the basic physiological adjustments to the orofacial area, and disturbances in this response may be related to orofacial dysfunctions. This review focuses on: i) the distinctive regulatory system of blood flow, especially parasympathetic vasodilation in the orofacial area; ii) their modulations, and; iii) the involvement of autonomic vasomotor responses in the physiological role of the orofacial functions, and in the etiology of orofacial dysfunctions related to disturbances of the autonomic nervous system.

The autonomic nervous and endocrine systems participate in homeostasis, which is a mechanism that keeps the internal environment at a certain set point. However, the set point of the internal environment fluctuates with biological rhythms and responses to external environmental changes. In addition, humans change the internal environment for behavior that will be executed in near future. For example, when exercising, it is necessary to increase the blood supply to the muscles. Therefore, the brain gives a command to increase the blood flow to the muscles via the autonomic nervous system at the same time as commanding the muscles to move. This prospective control is called a central command. Another is allostasis, which modulates the internal environment to actuate the emotional behaviors provoked by stress. Mismatches between allostasis and emotional behavior can lead to an abnormal physical condition in which stress-related physical symptoms develop. In this paper, we focus on changes in the internal environment and prediction and explain the role of the autonomic nervous system in allostasis and related disorders.

Recently, there have been many reports on the involvement of intestinal bacteria in the pathogenesis of neurological diseases. In particular, many reports have been made in multiple sclerosis, which is considered a representative immune disease, and Parkinson’s disease, which is a neurodegenerative disease. In the small intestine, intestinal bacteria are scarce and mostly aerobic, but in the large intestine, there are nearly 100 trillion bacteria, and their roles are very different. In this paper, we will review the roles of these two intestinal bacteria, including our research on Parkinson’s disease.

The age-related decline in muscle mass and strength (sarcopenia) may involve the role of the autonomic nervous system in skeletal muscle function in addition to the muscle and motor nervous systems. Muscle sympathetic nerves, which are considered to be adrenergic vasoconstrictors, are histologically distributed in muscle fibers and neuromuscular endplates, and may be involved in the maintenance of skeletal muscle mass and the regulation of contractility. We found that the triceps muscle tetanic force induced by tibial nerve stimulation was attenuated by cutting the lumbar sympathetic trunk, lumbar dorsal roots, or cervical spinal cord, and that reflex potentials were evoked in the lumbar sympathetic postganglionic fibers in response to muscle contraction, indicating that reflex excitation of sympathetic nerves by skeletal muscle contraction contributes to the maintenance of contractility of that muscle. The possibility that this mechanism diminishes with aging and may contribute to sarcopenia is discussed.

We developed interval walking training (IWT) and a training system using the internet of things (IoT) and examined the adherence to and effects of IWT for a long period. We found that the adherence over 22 months averaged 70% and was highly correlated with a 12% increase in peak aerobic capacity (VO2peak) and a 13% improvement in lifestyle-related diseases. To identify factors affecting the adherence, we performed multiple regression analysis and found that vasopressin V1a receptor polymorphisms could affect the adherence. Regarding the mechanism, we found in free-moving mice that cerebral activation suppressed baroreflex control of heart rate, which was followed by voluntary locomotion with increased arterial pressure; however, these responses were abolished in V1a receptor knockout and wild-type mice locally infused with a vasopressin V1a antagonist into the nucleus tractus solitarii. Moreover, in these V1a receptor-impaired mice, motivated behavior was particularly reduced with impaired central suppression of baroreflex control. Recently, we also observed increased cerebral blood flow and the following pressor response in humans when they intended to start exercise, and that these responses were enhanced in subjects with higher VO2peak. These results suggest that the central pressor response is associated with adherence to exercise training by making it easier to start voluntary exercise.

Exercise increases sympathetic nerve activity and arterial pressure simultaneously; this increase is sustained in proportion to exercise intensity. It is caused by an acute rightward and upward shift of the arterial baroreceptor reflex. In this study, we observed the acute rightward and upward shift of the baroreflex curve for renal sympathetic nerve activity during exercise in rats. Similar shifts in the baroreflex curve for sympathetic nerve activity may occur in the entire body, resulting in a uniform increase in sympathetic activity throughout the body during exercise. The increase in sympathetic nerve activity proportional to exercise intensity is likely caused by the afferent neuronal activity originating from the contracting muscle to the central nervous system; this afferent information results in activity proportional to the degree of muscle contraction. Although central command can change sympathetic nerve activity in an organ-specific manner, it acts to increase sympathetic nerve activity uniformly throughout the body during exercise. In this way, an acute shift in the arterial baroreceptor reflex causes a simultaneous and sustained increase in sympathetic nerve activity and arterial pressure during exercise.

Parasympathetic preganglionic neurons in the lumbosacral spinal cord have an important role on the micturition reflex. We have developed in vivo patch-clamp and extracellular recording techniques to detect excitation of the parasympathetic preganglionic neurons in the lumbosacral spinal cord in combination with urinary bladder contraction monitoring, and examined neuronal firings and synaptic responses evoked in the preganglionic neurons during micturition. In vivo extracellular recordings from the lumbosacral parasympathetic nucleus showed that spontaneous firing was detected in vivo with characteristic bursts of firing coinciding with the increases in intravesical pressure during micturition. In vivo whole-cell recordings of membrane potentials of spinal parasympathetic preganglionic neurons under current-clamp conditions showed similar bursts of action potentials associated with the increased intravesical pressure. Excitatory synaptic currents having different kinetics were evoked under voltage-clamp conditions in single parasympathetic preganglionic neurons, suggesting that parasympathetic preganglionic neurons make synaptic contacts with different neuronal populations. In this review, we show neuronal mechanisms of spinal parasympathetic preganglionic neurons on micturition, and also describe principles of in vivo electrophysiological recording techniques.

Exercise is known to provide multifaceted benefits in patients with cardiovascular diseases such as ischemic heart disease and heart failure. To maximize these benefits, it is necessary to understand the physiology of exercise-induced circulation. In particular, blood vessels have an important role in controlling circulation and the redistribution of blood to organs via contraction and relaxation while exercising. Regular exercise addresses abnormal sympathetic nerve activity and the renin-angiotensin-aldosterone system, as well as excessive vasoconstriction. It can also restore the vasodilatory response via improvement of vascular endothelial function. Improvement of the autonomic nervous system is expected in various modes of exercises.

In octogenarians, incidence of white matter disease (WMD), Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) are estimated as 80%: 33%: 7-8%, respectively (overlap included), and a combination of AD+WMD is the most common. In addition, diabetes that produces small fiber neuropathy is also common in octogenarians. Among autonomic disorders, orthostatic hypotension, overactive bladder and bowel motility dysfunction are common and all increase with age. Regarding pathophysiology, relation between diabetes, DLB with orthostatic hypotension, that between WMD, DLB (AD in part) with overactive bladder, and that between diabetes, DLB with bowel motility dysfunction have been postulated. Proper management for the autonomic dysfunction in older individuals is necessary to maximize quality of life in the patients.

Epipharyngeal abrasive therapy (EAT) is one of the treatments for chronic epipharyngitis. The purpose of this study was to elucidate the effect of EAT on autonomic function. Heart rate variability analysis was performed on the electrocardiogram records of 27 cases. EAT was classified into four events: resting, intranasal examination, nasal abrasing, and oral abrasing. Four items, HR, CVRR, ccv HF, and L/H, were measured during each of the four events and statistically examined. HR decreased and ccv HF increased during nasal abrasing. HR and CVRR increased during oral abrasing. The results suggest that EAT affecteds heart rate variability, and stimulateds parasympathetic nerves during nasal abrasing, and stimulateds both sympathetic and parasympathetic nerves during oral abrasing induceing the pharyngeal reflex. EAT was thoughtappears to activate autonomic function by reciprocal excitabilitytory and inhibitory stimulation.

One hundred twenty-six physically healthy women aged 45-55 years without organic disease were divided into three groups according to the classifications of Kyo (deficiency), Jitsu (excess), and Chukan (medium) used by the Japan Society of Oriental Medicine (JSOM). Their heart rate variability (HRV) was evaluated by the active tracer measurement method during supine rest, ergometer testing and post-ergometer sitting. There were no significant differences in HRV between rest and ergometer testing among the three groups, but during post ergometer sitting the Kyo group showed a lower HRV (CVRR, SDNN) than the other two groups (p＜0.05). In conclusion, from the standpoint of HRV activity, climacteric women without organic disease in the Kyo group showed lower autonomic recuperative ability.