Swallowing is a rare cause of neurally mediated syncope. The mechanism of swallow syncope that contributes to hypotension, bradycardia, or to both is complex. A 59-year-old man had experienced a recurrent loss of consciousness during swallowing of carbonated beverages or sticky foods. Another 59-year-old man had complained of intermittent syncope just after eating foods. These two patients had no significant structural or functional abnormalities in the esophagus or heart. Both cases showed bradycardia when the lower esophagus was stretched by balloon inflation. The activation of mechanoreceptors in the lower esophagus can be regarded as an initiating factor of these cardioinhibitions. The patients were treated with permanent pacemaker implantation and instructed to change eating habits, respectively.
Bradycardia/etiology ; Deglutition/*physiology ; Esophagus/*innervation ; Humans ; Male ; Mechanoreceptors/*physiology ; Middle Aged ; Syncope/*etiology

OBJECTIVETo explore the regeneration of mechanical sensory fibers after free nerve transplantation.

METHODNeuroelectrophysiological technique (single nerve fiber recording) was used to test the regeneration rate of mechanical sensory fibers, the proportion of rapidly and slowly adapting receptors, the stimulating thresholds of regenerated mechanoreceptors and conduction velocity of regenerated fibers. The regeneration pattern of the mechanoreceptors after free nerve transplantation to the rabbit reconstructed penis was also analyzed.

RESULTS9 months after operation, the number of regenerated mechanical sensory fiber was almost normal. The regenerated rapidly adapting receptors had a higher proportion with higher mature degree than the regenerated slowly adapting receptors. 9 months after nerve transplantation the stimulating thresholds of regenerated mechanoreceptors and conduction velocity of regenerated fibers remained below normal.

CONCLUSIONAfter free nerve transplantation to the rabbit reconstructed penis, the function of both rapidly and slowly adapting sensory nerve fiber partially recovered, but in different extent.

Animals ; Ganglia, Sensory ; physiology ; Male ; Mechanoreceptors ; physiology ; Nerve Fibers ; transplantation ; Nerve Regeneration ; Penis ; surgery ; Rabbits

OBJECTIVETo compare the ultra-microscopic changes of periodontal Ruffini's corpuscle induced by different patterns of tooth movement, and investigate the influence of different changes of the periodontal mechanical environment on the periodontal mechanoreceptor.

METHODSThirty-two eight-weeks-old SD rats were divided into control group (n = 4), none-extraction group (n = 12) and extraction group (n = 12), and none-extraction group and extraction group were further divided into three subgroups, namely 3 day and 14 day and 28 day. For control group, no intervention was performed. For none-extraction group and extraction group, the following interventions were conducted. In none-extraction group, the maxillary left and mandibular right third molars were moved distally. In extraction group, the maxillary left third molar was moved distally, and the bilateral mandibular third molars were extracted. The ultra-structures of periodontal Ruffini's corpuscle in the periodontal ligament of the distal root of the bilateral maxillary third molars were observed under the transmission electron microscope.

RESULTSThe ultra-structrural changes in the none-extraction group were mainly characterized by degeneration or abnormal distribution of mitochondria in the axon terminal, which were almost recovered at 28 d. In the extraction group, the changes were mainly characterized by deficiency or abnormal elongation of the Schwann sheath and were not recovered at 28 d.

CONCLUSIONSThe ultra-structures of periodontal Ruffini's corpuscle might be influenced by tooth movement and occlusal changes, and the mechanorecepting function of it might be affected by changes of the periodontal mechanical environment.

Animals ; Mechanoreceptors ; physiology ; Molar ; Molar, Third ; Periodontal Ligament ; Rats ; Tooth Movement Techniques ; Tooth Root

Breathing is critically depending on a variety of sensory feedbacks from multiple sources for its optimal performance. The sensory information from the lung and airways probably provides one of the most important feedbacks to adjust the respiratory controller to generate optimal breathing movements. Since Breuer and Hering made the seminal report regarding role of the vagus nerve in control of breathing in 1868, airway sensory receptors have been a subject for intensive and extensive studies. After more than a century investigation, our knowledge accumulates immensely, however, our understanding of the nature of these sensory receptors is still far from complete. This brief review provides an overview on this topic.
Humans ; Lung ; innervation ; physiology ; Mechanoreceptors ; physiology ; Neuroepithelial Bodies ; physiology ; Pulmonary Stretch Receptors ; physiology ; Reflex ; physiology ; Respiratory System ; innervation ; Vagus Nerve ; physiology

The method of isolating filaments of the dorsal cutaneous branches was used to observe the effects of antidromic electrical stimulation of the spinal nerves on the discharge of remote A delta and C mechanoreceptive units in rats. Seventy-nine mechanoreceptive units were recorded from the T12 nerve filaments after stimulation of the dorsal cutaneous branches of T9 spinal nerve. It was found that the discharge frequency of 59.3% (16/27) A delta-units and 71.2% (37/52) C-units significantly increased during 90-120 s after the stimulation. Sixty-four mechanoreceptive units were recorded from the T12 nerve filaments after stimulation of the dorsal cutaneous branches of T8 spinal nerves. The discharge frequency of 47.8% (11/23) A delta-units and 36.6% (15/41) C-units significantly increased during 120-150 s after the stimulation. In addition, the threshold of the majority of these mechanoreceptors (78.3%, 18/23) decreased after the stimulation. The results suggest that antidromic electrical stimulation of the dorsal cutaneous branches of spinal nerves leads to sensitization of A delta and C mechanoreceptive units of the remote peripheral nerve endings, which results in an increase in afferent discharge of these units.
Animals ; Electric Stimulation ; Electrophysiology ; Female ; In Vitro Techniques ; Male ; Mechanoreceptors ; physiology ; Rats ; Rats, Sprague-Dawley ; Spinal Nerves ; anatomy & histology ; physiology

The purpose of the present study was to observe whether primary afferent Abeta-fiber is involved in the information transmission between peripheral terminals of adjacent dermatomes. The dorsal cutaneous nerve branches of spinal nerves from T(8) to T(12) segments were cut proximally. One peripheral stump end of the cut nerves was dissected into a few filaments for the examination of mechanoreceptive properties of single Abeta-fibers and their discharges were observed while the other end was stimulated antidromically. Fifty Abeta-units were recorded in forty-two intact rats. After an electrical stimulation (0.45 mA, 0.1 ms, 20 Hz, for 10 s) was delivered to the stimulated nerve, the size of the receptive field of 60.6% (n=33) Abeta-fibers extended. The mean area of receptive fields of all examined units enlarged from 8.94+/-6.51 mm(2) to 20.34+/-16.17 mm(2) (P<0.01) and the shapes of the receptive fields of 81.8% (n=20) units changed from a dot, round or ellipse with its long axis in parallel with the longitudinal axis of the body to an oblique ellipse with the longitudinal axis of the body. The mechanoreceptive threshold of 68.0% (n=50) units decreased with a reduction in mean threshold from 2.37+/-1.24 to 2.29+/-1.24 mN (P<0.05). The duration of these changes in mechano-receptive properties increased from 52.23+/-9.27 to 56.93+/-15.76 min. Meanwhile, increasing discharge was found in 50.0% (n=50) units but lasted only for 1.52+/-0.46 min. The changes in mechanoreceptive properties appeared simultaneously with discharge changes but had longer duration than that of discharge change (P<0.01). Discharges changes usually appeared in those units with the changes in mechanoreceptive properties following an antidromical electrical stimulation of adjacent spinal segment. These results suggest that low-threshold mechanoreceptive Abeta-fibers are affected by antidromical electrical stimulation of the cutaneous nerve from an adjacent spinal segment, indicating that information transmission occurs between the two endings of peripheral afferent nerves from adjacent spinal segments without any involvement of the central nervous system, and that Abeta-fibers are involved in the process of information transmission between peripheral terminals from adjacent spinal segments.
Afferent Pathways ; physiology ; Animals ; Electric Stimulation ; Mechanoreceptors ; physiology ; Neural Conduction ; physiology ; Peripheral Nerves ; physiology ; Rats ; Rats, Sprague-Dawley ; Skin ; innervation ; Spinal Nerves ; physiology

Intraganglionic laminar endings (IGLEs) have been supposed to be the mechanoreceptors in the gut by electrophysiological recording techniques. But the specialized morphology of IGLEs could not be displayed closely associated with this function and the mechanism that IGLEs act as the mechanotransduction sites in the gut is not yet well understood. In the present study, we used styryl dye FM1-43 combined with stretch stimulation in the guinea pig esophagus to test whether IGLEs acted as the mechano-sensitive receptors of the vagal afferent nerves. At the same time, the special structure of IGLEs displayed by FM1-43 was further confirmed by neurobiotin anterograde labeling technique. To further investigate the characteristics of IGLEs as mechanosensitive receptors, different drugs were used to block or stimulate IGLEs activation. Our results indicated that only in the stretched preparation could FM1-43 enter the IGLEs and completely display their specialized structure, which was consistent with that shown by neurobiotin. The amount of IGLEs shown by stretch-evoked FM1-43 staining was much more than that shown without stretch stimulation [(90.4 +/- 9.5) % vs (10.7 +/- 2.1) %, P<0.05]. Ca(2+), TTX (0.6 mumol/L), atropine (0.6 mumol/L), SKF (50 mumol/L), and gadolium (100 mumol/L) had no effect on the IGLEs activation. But for benzamil (100 mumol/L), an epithelial sodium channel blocker, activation of IGLEs by stretch stimulation was significantly blocked. The potent ATP analogue, alpha,beta-methylene ATP (100 mumol/L) could not activate FM1-43 staining without stretch. These results indicate that IGLEs are sensitive to mechanical stimulation. This could lead to the deduction that IGLEs act as the mechanoreceptors of vagal afferent nerve. IGLEs could transmit mechanical stimuli directly through ion channels, independent of neurotransmitter release and action potential propagation. The stretch-sensitive channels on IGLEs probably belong to the epithelial sodium channel family rather than voltage-gated sodium ion channels. Furthermore, styryl dye FM1-43 is a useful activity-dependent marker to demonstrate the structure and function of IGLEs in guinea pig esophagus.
Afferent Pathways ; physiology ; Animals ; Esophagus ; innervation ; Female ; Ganglia, Autonomic ; physiology ; Guinea Pigs ; Male ; Mechanoreceptors ; physiology ; Nerve Endings ; physiology ; Vagus Nerve ; physiology

PURPOSE: The purpose of this study was to investigate the activation of the respiratory centers during insufflation of the larynx with CO2 at different flow rates and concentrations. MATERIALS AND METHODS: The experiments were carried out in spontaneous air breathing rabbits, anesthetized with thiopental sodium (25mg kg(-1) i.v.). The larynx was separated from the oropharyngeal cavity and the trachea. The tidal volume (VT) and respiratory frequency (f min(-1)) were recorded from the lower tracheal cannula. The respiratory minute volume (VE) was calculated, the action potentials from the right phrenic nerve were recorded and the inspiratory (TI) and expiratory (TE) periods and the mean inspiratory flow rate (VT/TI) were calculated. The larynx was insufflated at flow rates of 500mL min(-1) and 750mL min(-1), with 7 and 12% CO2-Air by means of a respiratory pump. RESULTS: Insufflation of the larynx, with both gas mixtures, decreased the f and VT significantly. The TI and TE were found to increase significantly due to the decreasing in f. There was a significant decrease in VT/TI ratio. Following bilateral midcervical vagotomy, on the passing of both gas mixtures, significant decreases were observed in the VT, and the responses of f, TI and TE were abolished. After cutting the superior laryngeal nerve, the responses of the VT to both gas mixtures were abolished. CONCLUSION: In conclusion, the results of this study purpose that the stimulation of the laryngeal mechanoreceptors by the effect of hyper- capnia decreases the activation of the respiratory center
Air ; Animals ; Carbon Dioxide/chemistry/*pharmacology ; Female ; Laryngeal Nerves/drug effects/physiology ; Male ; Mechanoreceptors/drug effects/physiology ; Rabbits ; Reflex/*drug effects/physiology ; *Respiratory Mechanics/drug effects ; Tidal Volume

Spinal dorsal horn neurons play an important role in the processing of sensory information and are also targets of modulation by both endogenous and exogenous drugs. Propofol is an intravenous anesthetic and whether it has direct modulatory actions on sensory neuronal responses of the spinal cord dorsal horn has not been well studied. In the present study, a single dose (0.5 micromol) of propofol dissolved in dimethyl sulfoxide (DMSO) was directly applied onto the dorsal surface of the spinal cord and its effect was evaluated in 25 wide-dynamic-range (WDR) neurons and 10 low-threshold mechanoreceptive (LTM) neurons by using extracellular single unit recording technique in sodium pentobarbital anesthetized rats. Compared with the DMSO treatment, propofol produced a significant inhibition of WDR neuronal activity evoked by both noxious heat (45, 47, 49 or 53 degrees C, 15 s) and mechanical (pinch, 10 s) stimuli applied to their cutaneous receptive fields (cRF) on the ipsilateral hind paw skin. To investigate whether propofol exerts a modulatory effect on non-nociceptive afferent-mediated activity, the responses of WDR or LTM neurons to non-noxious brush and pressure were also evaluated. The non-noxious mechanically-evoked responses of both WDR and LTM neurons were significantly suppressed by propofol. The present results indicate that propofol has direct actions on the dorsal horn neurons of the spinal cord in rats. However, since both non-nociceptive and nociceptive afferent-mediated activity can be suppressed, the spinal effects of propofol are not likely to be specifically associated with anti-nociception.
Anesthetics, Intravenous ; Animals ; Dimethyl Sulfoxide ; Electrophysiology ; Male ; Mechanoreceptors ; drug effects ; Nociceptors ; physiology ; Posterior Horn Cells ; physiology ; Propofol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; physiology

OBJECTIVETo investigate the role of activated brain regions in Parkinson's disease (PD) during tactile stimulation.

METHODSTwenty-one patients with early PD[mean age (60.43 +/-9.65)y] and twenty-two age-matched healthy controls [mean age (59.23 +/-11.12)y] were enrolled in the study. All the patients were tested by the United Parkinson Disease Rating Scale (UPDRS) as the evaluation of the disease severity. A block design was used when the finger tactile stimulation was given to the subjects. The hypoactive and hyperactive regions of PD patients were confirmed first, which were identified as regions of interest (ROI). ROI analysis was performed to quantify BOLD signal changes when subjects were under tactile stimulation. The correlations of signal changes with disease severity, and correlations of hyperactive with hypoactive regions were analyzed.

RESULTSRight primary sensory and motor cortex, right supplementary motor area (SMA), bilateral caudates, bilateral precuneus, bilateral occipital visual cortex and left middle temporal gyrus were hypoactivated in PD, while right prefrontal cortex (PFC) and right caudate were hyperactivated. The hypoactivation of right SMA was negatively correlated with disease severity. All the hypoactive and hyperactive regions were positively correlated with activation of caudates. There was a positive correlation between hyperactive PFC and hypoactive regions.

CONCLUSIONSThe signal change of SMA is directly related to disease severity in early PD, and caudates may play a significant role in PD tactile processing. The hyperactivation of PFC may be not a compensation but a pathophysiological change related to PD neural dysfunction.

Aged ; Brain ; physiopathology ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Mechanoreceptors ; physiology ; Middle Aged ; Parkinson Disease ; physiopathology ; Severity of Illness Index ; Time Factors ; Touch ; physiology ; Touch Perception ; physiology