scholarly journals Specialized mechanoreceptor systems in rodent glabrous skin

2018 ◽  
Author(s):  
Jan Walcher ◽  
Julia Ojeda-Alonso ◽  
Julia Haseleu ◽  
Maria K. Oosthuizen ◽  
Ashlee H. Rowe ◽  
...  
Keyword(s):  
Small Group ◽  
Rodent Species ◽  
Glabrous Skin ◽  
Skin Area ◽  
Mechanical Stimuli ◽  
Orientation Sensitivity ◽  
Hairy Skin ◽  
Physiological Properties ◽  
Sensory Fibers ◽  
Very High

AbstractRodents use their forepaws to actively interact with their tactile environment. Studies on the physiology and anatomy of glabrous skin that makes up the majority of the forepaw are almost non-existent in the mouse. Here we developed a preparation to record from single sensory fibers of the forepaw and compared anatomical and physiological receptor properties to those of the hind paw glabrous and hairy skin. We found that the mouse forepaw skin is equipped with a very high density of mechanoreceptors; >3 fold more than hind paw glabrous skin. In addition, rapidly adapting mechanoreceptors that innervate Meissner’s corpuscles of the forepaw were several-fold more sensitive to slowly moving mechanical stimuli compared to their counterparts in the hind paw glabrous skin. All other mechanoreceptors types as well as myelinated nociceptors had physiological properties that were invariant regardless of which skin area they occupied. We discovered a novel D-hair receptor innervating a small group of hairs in the middle of the hind paw glabrous skin in mice. Glabrous D-hair receptors were direction sensitive albeit with an orientation sensitivity opposite to that described for hairy skin D-hair receptors. Glabrous D-hair receptors do not occur in all rodents, but are present in North American and African rodent species that diverged more than 65 million years ago. The function of these specialized hairs is unknown, but they are nevertheless evolutionarily very ancient. Our study reveals novel physiological specializations of mechanoreceptors in the glabrous skin that likely evolved to facilitate tactile exploration.

Antiallodynic Effects of Systemic and Intrathecal Morphine in the Spared Nerve Injury Model of Neuropathic Pain in Rats

2004 ◽  
Vol 100 (4) ◽  
pp. 905-911 ◽  
Author(s):  
Chengshui Zhao ◽  
Jill M. Tall ◽  
Richard A. Meyer ◽  
Srinivasa N. Raja
Keyword(s):  
Neuropathic Pain ◽  
Nerve Injury ◽  
Mechanical Allodynia ◽  
Intrathecal Morphine ◽  
Spinal Nerve ◽  
Glabrous Skin ◽  
Mechanical Stimuli ◽  
Spared Nerve Injury ◽  
Withdrawal Threshold ◽  
Hairy Skin

Background The efficacy of opioids for neuropathic pain remains controversial. The effects of morphine on pain behavior were investigated in two animal models of neuropathic pain: the spared nerve injury (SNI) model and the spinal nerve ligation (SNL) model. Methods Nerve injuries were created in rats either by tight ligation and section of the left tibial and common peroneal nerves (SNI) or by unilateral ligation of L5 and L6 spinal nerves (SNL). Paw withdrawal threshold to mechanical stimuli was measured using the up-down method in the hairy and glabrous skin territories of the sural nerve for SNI rats or in the mid-plantar paw of SNL rats. Results Before SNI, the median paw withdrawal thresholds in hairy and glabrous skin were similar (26 g [25%, 75% quartiles: 26, 26 g]). The paw withdrawal threshold decreased after SNI in both hairy and glabrous skin (P < 0.001). Thirty days after the SNI, the threshold in hairy skin (0.3 g) was significantly lower than in glabrous skin (1.9 g; P < 0.001). In blinded experiments, both subcutaneous and intrathecal morphine (0.1-10 microg) dose-dependently attenuated mechanical allodynia induced by SNI measured in the hairy skin, an effect that was naloxone reversible. The ED50 for the intrathecal morphine was 0.52 microg (95% confidence interval, 0.31-0.90 microg). Morphine (1 microg intrathecal) attenuated SNI-induced mechanical allodynia in glabrous skin with potency similar to that in hairy skin. In SNL rats, morphine (30 microg intrathecal) almost completely reversed the SNL-induced mechanical allodynia. Conclusions (1) SNI-induced mechanical allodynia is characterized by a lower paw withdrawal threshold in hairy versus glabrous skin; (2) systemic and intrathecal morphine reverse SNI-induced mechanical allodynia in a dose-dependent fashion; and (3) intrathecal morphine also reverses SNL-induced mechanical allodynia. These results suggest that intrathecal opioids are likely to be effective in the treatment of neuropathic pain.

scholarly journals The Effect of PQRST and SGD Methods on Students’ Reading Comprehension at Dehasen University

2018 ◽  
Vol 1 (2) ◽  
pp. 86-98
Author(s):  
Mariska Febrianti
Keyword(s):  
Reading Comprehension ◽  
Small Group ◽  
Group Discussion ◽  
General Information ◽  
Reading Test ◽  
Small Group Discussion ◽  
Significant Difference ◽  
Post Test ◽  
Reading To Learn ◽  
Very High

This research aims to compare the effectiveness of two methods, PQRST (Preview, Question, Read, State and Test) and SGD (Small Group Discussion). It was carried out at the second semester students of Penjaskesrek Department, Dehasen University. The design was a quasi-experiment. The sample consisted of two classes; one was taught by the PQRST method and another by the SGD method. The instrument was a reading test, which was tried-out; the reliability was 0.917 (very high). The result was as follows: at the pretest, there was no significant difference between both group on all aspects and at the post test, there were no significant difference between both groups on general comprehension, reading to learn from the text, and reading to integrate information. However, SGD was found to be more effective on finding general information while PQRST was found to be more effective on reading to skim and finding simple information.

scholarly journals Tiling and somatotopic alignment of mammalian low-threshold mechanoreceptors

2019 ◽  
Vol 116 (19) ◽  
pp. 9168-9177 ◽  
Author(s):  
Emily D. Kuehn ◽  
Shan Meltzer ◽  
Victoria E. Abraira ◽  
Cheng-Ying Ho ◽  
David D. Ginty
Keyword(s):  
Spinal Cord ◽  
Sensory Neurons ◽  
Hair Follicles ◽  
Mechanical Stimuli ◽  
Central Projections ◽  
Axonal Projections ◽  
Hairy Skin ◽  
Static Indentation ◽  
Innervation Patterns ◽  
Low Threshold

Innocuous mechanical stimuli acting on the skin are detected by sensory neurons, known as low-threshold mechanoreceptors (LTMRs). LTMRs are classified based on their response properties, action potential conduction velocity, rate of adaptation to static indentation of the skin, and terminal anatomy. Here, we report organizational properties of the cutaneous and central axonal projections of the five principal hairy skin LTMR subtypes. We find that axons of neurons within a particular LTMR class are largely nonoverlapping with respect to their cutaneous end organs (e.g., hair follicles), with Aβ rapidly adapting-LTMRs being the sole exception. Individual neurons of each LTMR class are mostly nonoverlapping with respect to their associated hair follicles, with the notable exception of C-LTMRs, which exhibit multiple branches that redundantly innervate individual hair follicles. In the spinal cord, LTMR central projections exhibit rostrocaudal elongation and mediolateral compression, compared with their cutaneous innervation patterns, and these central projections also exhibit a fine degree of homotypic topographic adjacency. These findings thus reveal homotypic tiling of LTMR subtype axonal projections in hairy skin and a remarkable degree of spatial precision of spinal cord axonal termination patterns, suggesting a somatotopically precise tactile encoding capability of the mechanosensory dorsal horn.

scholarly journals Evidence for sparse C-tactile afferent innervation of glabrous human hand skin

2020 ◽  
Author(s):  
Roger H Watkins ◽  
Mariama Dione ◽  
Rochelle Ackerley ◽  
Helena Backlund Wasling ◽  
Johan Wessberg ◽  
...  
Keyword(s):  
Firing Frequency ◽  
Glabrous Skin ◽  
Whole Body ◽  
Human Hand ◽  
Hairy Skin ◽  
Ct Afferents ◽  
Touch Perception ◽  
The Face ◽  
Nerve Recordings ◽  
Future Work

C-tactile (CT) afferents were long-believed to be lacking in humans, but were subsequently shown to densely innervate the face and arm skin, and to a lesser extent the leg. Their firing frequency to stroking touch at different velocities has been correlated with ratings of tactile pleasantness. CT afferents were thought to be absent in human glabrous skin; however, tactile pleasantness can be perceived across the whole body, including glabrous hand skin. We used microneurography to investigate mechanoreceptive afferents in the glabrous skin of the human hand, during median and radial nerve recordings. We describe CTs found in the glabrous skin, with comparable characteristics to those in hairy arm skin, and detail recordings from three such afferents. CTs were infrequently encountered in the glabrous skin and we estimate that the ratio of recorded CTs relative to myelinated mechanoreceptors (1:80) corresponds to an absolute innervation density of around 7 times lower than in hairy skin. This sparse innervation sheds light on discrepancies between psychophysical findings of touch perception on glabrous skin and hairy skin, although the role of these CT afferents in the glabrous skin remains subject to future work.

Parallel processing of tactile information in the cerebral cortex of the cat: effect of reversible inactivation of SI on responsiveness of SII neurons

1992 ◽  
Vol 67 (2) ◽  
pp. 411-429 ◽  
Author(s):  
A. B. Turman ◽  
D. G. Ferrington ◽  
S. Ghosh ◽  
J. W. Morley ◽  
M. J. Rowe
Keyword(s):  
Phase Locking ◽  
Receptive Fields ◽  
Mechanical Stimulus ◽  
Glabrous Skin ◽  
Mechanical Stimuli ◽  
Sinusoidal Vibration ◽  
Response Level ◽  
Reversible Inactivation ◽  
Stimulus Response ◽  
Cortical Cooling

1. Localized cortical cooling was employed in anesthetized cats for the rapid reversible inactivation of the distal forelimb region within the primary somatosensory cortex (SI). The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI. 2. Response features were examined quantitatively before, during, and after SI inactivation for 29 SII neurons, the tactile receptive fields of which were on the glabrous or hairy skin of the distal forelimb. Controlled mechanical stimuli that consisted of l-s trains of either sinusoidal vibration or rectangular pulses were delivered to the skin by means of small circular probes (4- to 8-mm diam). 3. Twenty-three of the 29 SII neurons (80%) showed no change in response level (in impulses per second) as a result of SI inactivation. These included seven neurons activated exclusively or predominantly by Pacinian corpuscle (PC) receptors, six that received hair follicle input, four activated by convergent input from hairy and glabrous skin, and six driven by dynamically sensitive but non-PC inputs from the glabrous skin. 4. Six SII neurons (20%), also made up of different functional classes, displayed a reduction in response to cutaneous stimuli when SI was inactivated. 5. Stimulus-response relations, constructed by plotting response level in impulses per second against the amplitude of the mechanical stimulus, showed that the effect of SI inactivation on individual neurons was consistent over the whole response range. 6. The reduced response level seen in 20% of SII neurons in association with SI inactivation cannot be attributed to direct spread of cooling from SI to the forelimb area of SII, as there was no evidence for a cooling-induced prolongation in SII spike waveforms, an effect that is known to precede any cooling-induced reduction in responsiveness. 7. As SI inactivation produced a fall in spontaneous activity in the affected SII neurons, we suggest that the inactivation removes a source of background facilitatory influence that arises in SI and affects a small proportion of SII neurons. 8. Phase-locking and therefore the precision of impulse patterning were unchanged in the responses of SII neurons to vibration during SI inactivation. This was the case whether response levels of neurons were reduced or unchanged by SI inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

The 15-lipoxygenase product, 8R,15S-diHETE, stereospecifically sensitizes C-fiber mechanoheat nociceptors in hairy skin of rat

1990 ◽  
Vol 63 (5) ◽  
pp. 966-970 ◽  
Author(s):  
D. M. White ◽  
A. I. Basbaum ◽  
E. J. Goetzl ◽  
J. D. Levine
Keyword(s):  
Arachidonic Acid ◽  
Acid Metabolism ◽  
Arachidonic Acid Metabolism ◽  
Thermal Stimulus ◽  
Mechanical Stimuli ◽  
Noxious Heat ◽  
Lipoxygenase Product ◽  
Hairy Skin ◽  
Mechanical Threshold ◽  
C Fiber

1. This study examined the effects of the 15-lipoxygenase product of arachidonic acid metabolism, (8R,15S)-dihydroxyicosa-(5E-9,11,13Z)tetraenoic acid (8R,15S-diHETE), on mechanical thresholds and thermal responses of saphenous nerve cutaneous C-fiber nociceptors that innervate the hairy skin of the rat hindpaw. Single C-fiber mechanoheat nociceptors (C-MH) that had von Frey hair (VFH) thresholds greater than 5 g and were activated by a noxious heat stimulus were chosen for study. We also studied the effects of prostaglandin E2 (PGE2), a cyclooxygenase product of arachidonic acid metabolism, on these nociceptors. 2. The 63 C-MHs studied had a conduction velocity of 0.82 +/- 0.03 m/s (mean +/- SE) and a mechanical threshold of 13.4 +/- 2.4 g. In a subgroup of these (n = 24), the thermal threshold was measured as (44 +/- 1 degree C) (mean +/- SE). 3. 8R,15S-diHETE produced a significant decrease in mechanical threshold of C-MHs (n = 33). The 8R,15S-diHETE-induced sensitization of C-MHs to mechanical stimuli was completely antagonized by coadministration with a stereoisomer, 8S,15S-diHETE (n = 10). 4. The mechanical threshold of C-MHs (n = 10), previously injected with the combination of 8R,15S-diHETE and 8S,15S-diHETE, was significantly reduced by a subsequent injection of PGE2. In a separate group of C-MHs (n = 7), PGE2 was co-injected with 8S,15S-diHETE, which failed to antagonize the sensitizing effect of PGE2 on mechanical threshold. 5. 8R,15S-diHETE also sensitized C-MHs (n = 9) to a thermal stimulus consisting of 37 degrees C for 5 min.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Stress-Induced Mast Cell Activation in Glabrous and Hairy Skin

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Constantin Căruntu ◽  
Daniel Boda ◽  
Sorin Musat ◽  
Ana Căruntu ◽  
Eugen Mandache
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Prolonged Exposure ◽  
Mast Cell Degranulation ◽  
Mast Cell Activation ◽  
Glabrous Skin ◽  
Stress Exposure ◽  
Hairy Skin ◽  
The Impact

Mast cells play a key role in modulation of stress-induced cutaneous inflammation. In this study we investigate the impact of repeated exposure to stress on mast cell degranulation, in both hairy and glabrous skin. Adult male Wistar rats were randomly divided into four groups: Stress 1 day(n=8), Stress 10 days(n=7), Stress 21 days(n=6), and Control(n=8). Rats in the stress groups were subjected to 2 h/day restraint stress. Subsequently, glabrous and hairy skin samples from animals of all groups were collected to assess mast cell degranulation by histochemistry and transmission electron microscopy. The impact of stress on mast cell degranulation was different depending on the type of skin and duration of stress exposure. Short-term stress exposure induced an amplification of mast cell degranulation in hairy skin that was maintained after prolonged exposure to stress. In glabrous skin, even though acute stress exposure had a profound stimulating effect on mast cell degranulation, it diminished progressively with long-term exposure to stress. The results of our study reinforce the view that mast cells are active players in modulating skin responses to stress and contribute to further understanding of pathophysiological mechanisms involved in stress-induced initiation or exacerbation of cutaneous inflammatory processes.

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