Teeth Clenching and Positive Acceleration-Induced Cerebral Arterial Hypotension in Rats

The role of the autonomic nervous system (ANS) was recently investigated in Temporomandibular disorders (TMD). Several authors argue that in subjects with TMD there is a dysregulation of ANS. Recent literature support that Pupillometry is a simple non-invasive tool to study ANS. The aim of this study was to investigate the relationship between TMD and ANS activity using pupillometry recording in Infrared light at rest Mandible Position (RP); Infrared light at Forced Habitual Occlusion (FHO); Yellow-green light at RP; Yellow-green light at FHO. Forty female subjects were enrolled: 20 case patients showed TMD based on the Research Diagnostic Criteria for TMD, and 20 control patients, aged matched, had no signs or symptoms of TMD. Statistical analysis was performed on average pupil size. Ratio between pupil size in FHO and RP (FHO/RP ratio) and yellow-green and infrared (light/darkness ratio) lighting were carried out. Within group differences of pupil size and of “ratio” were analyzed using a paired t test, while differences of pupil size between groups were tested using an unpaired t test. Statistical comparisons between groups showed no significant differences of absolute values of pupil dimension in RP and FHO, both in yellow-green and in infrared lighting. In addition, there were no significant differences within groups comparing RP and FHO in yellow-green light. In within group comparison of pupil size, differences between RP and FHO were significant in infrared conditions. Control subjects increased, whereas TMD patients decreased pupil size at FHO in infrared lightening. FHO/RP ratio in darkness and light/darkness ratio in RP were significantly different between groups. Taken together, these data suggest that TMD subjects have an impairment of the sympathetic-adrenergic component of the ANS to be activated under stress. The present study provides preliminary pupillometric data confirming that adrenergic function is dysregulated in patients with TMD.

show abstract

“…Clenching, in fact, produces sympathetic activation, partly via an increase of blood flow and pressure of the head [31], [32], [33].…”

Section: Discussionmentioning

confidence: 99%

Dysregulation of the Autonomous Nervous System in Patients with Temporomandibular Disorder: A Pupillometric Study

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Meanwhile, investigating gravity-induced deformation and instability in biological tissues holds great significance for ensuring the safety of astronauts in extreme hypergravity environments. [149][150][151][152][153] Understanding the mechanisms behind these phenomena can aid in developing protective measures and designing suitable materials for space exploration. To this end, gravity-induced instabilities provide a versatile platform for various applications, ranging from the fabrication of surface patterns to the measurement of mechanical properties.…”

Section: Applications Of Gravity-induced Instabilitiesmentioning

confidence: 99%

Harnessing Gravity‐Induced Instability of Soft Materials: Mechanics and Application

Lü,

Li,

et al. 2024

Adv Funct Materials

View full text Add to dashboard Cite

This work offers a comprehensive overview of how gravity affects soft materials, with a particular emphasis on gravity‐induced instability. Soft materials, including biological tissues, elastomers, and gels, are characterized by low elastic moduli and the ability to undergo significant deformations. These large deformations can lead to instabilities and the emergence of distinctive surface patterns when even small perturbations are introduced. An in‐depth understanding of these gravity‐induced instabilities in soft materials is of paramount importance for both fundamental scientific research and practical applications across diverse domains. The underlying mechanisms governing these instabilities are delved in and elucidate the techniques employed to study and manipulate them. Further, the gravity‐induced wrinkling and the Rayleigh‐Taylor (RT) instability in soft materials are zoomed in, highlighting how altered gravity environments impact natural and synthetic systems. Lastly, current and potential applications are underscored where gravity‐induced instabilities are already making an impact or may hold promise in the near future. In sum, the exploration of gravity‐induced instabilities in soft materials paves the way for innovative applications and advancements in a wide range of fields.

show abstract

“…Then, dantrolene, a postsynaptic skeletal muscle relaxant, was administered to reduce masseter muscle contraction even when electrically stimulated in the same seven rats. Dantrolene markedly reduced clenching force and abolished the teeth clinching-evoked protection from 1.5-Gz-induced hypotension (decrease by 18.9 ± 2.6 mmHg for the teeth clenching with Dantrolene group) [ 37 , 48 , 49 ] …”

Section: Effects Of Using An Anti-g Systemmentioning

confidence: 99%

“…Following systemic administration of a postsynaptic skeletal muscle relaxant, dantrolene, the masseter electrical stimulation induced no appreciable increase in AP or HR [ 48 ]. These findings indicated that the pressor response under masseter contraction was specifically induced by the teeth-clenching action, and we accordingly named it the “teeth-clenching pressor response” [ 48 ]. The receptors and reflex mechanisms for the pressor response are now investigating and be on the way [ 49 ].…”

Section: Trials To Protect the Brain Autonomicallymentioning

confidence: 99%

See 1 more Smart Citation

Effects and biological limitations of +Gz acceleration on the autonomic functions-related circulation in rats

Nishida

Maruyama²,

Shouji

et al. 2016

J Physiol Sci

Self Cite

View full text Add to dashboard Cite

The effects of gravitational loading (G load) on humans have been studied ever since the early 20th century. After the dangers of G load in the vertical head-to-leg direction (+Gz load) became evident, many animal experiments were performed between 1920 and 1945 in an effort to identify the origins of high G-force-induced loss of consciousness (G-LOC), which led to development of the anti-G suit. The establishment of norms and training for G-LOC prevention resulted in a gradual decline in reports of animal experiments on G load, a decline that steepened with the establishment of anti-G techniques in humans, such as special breathing methods and skeletal muscle contraction, called an anti-G straining maneuver, which are voluntary physiological functions. Because the issue involves humans during flight, the effects on humans themselves are clearly of great importance, but ethical considerations largely preclude any research on the human body that probes to any depth the endogenous physiological states and functions. The decline in reports on animal experiments may therefore signify a general decline in research into the changes seen in the various involuntary, autonomic functions. The declining number of related reports on investigations of physiological autonomic systems other than the circulatory system seems to bear this out. In this review, we therefore describe our findings on the effects of G load on the autonomic nervous system, cardiac function, cerebral blood flow, tissue oxygen level, and other physiological autonomic functions as measured in animal experiments, including denervation or pharmacological blocking, in an effort to present the limits and the mechanisms of G-load response extending physiologically. We demonstrate previously unrecognized risks due to G load, and also describe fundamental research aimed at countering these effects and development of a scientific training measure devised for actively enhancing +Gz tolerance in involuntary, autonomic system functions. The research described here is rough and incomplete, but it is offered as a beginning, in the hope that researchers may find it of reference and carry the effort toward completion. The advances described here include (1) a finding that cerebral arterial perfusion pressure decreases to nearly zero under +5.0 Gz loads, (2) indications that G load may cause myocardial microinjuries, (3) detection of differences between cerebral regions in tissue-oxygen level under +3.0 Gz load, (4) discovery that hypotension is deeper under decreasing +Gz loads than increasing +Gz loads with use of an anti-G system, due in part to suppression of baroreceptor reflex, and (5) revelations and efforts investigating new measures to reduce cerebral hypotension, namely the “teeth-clenching pressor response” and preconditioning with slight but repeated G loads.

show abstract

Teeth Clenching and Positive Acceleration-Induced Cerebral Arterial Hypotension in Rats

Abstract: Our results suggest that teeth clenching induced a pressor response that prevented +Gz-induced cerebral hypotension, which suggests the possible development of a new anti-G method.

Cited by 4 publications

References 0 publications

Dysregulation of the Autonomous Nervous System in Patients with Temporomandibular Disorder: A Pupillometric Study

Dysregulation of the Autonomous Nervous System in Patients with Temporomandibular Disorder: A Pupillometric Study

Harnessing Gravity‐Induced Instability of Soft Materials: Mechanics and Application

Effects and biological limitations of +Gz acceleration on the autonomic functions-related circulation in rats

Contact Info

Product

Resources

About