scholarly journals Itch and Cough – Similar Role of Sensory Nerves in Their Pathogenesis

2020 ◽  
pp. S43-S54
Author(s):  
T. Pecova ◽  
I. Kocan ◽  
R. Vysehradsky ◽  
R. Pecova
Keyword(s):  
Sensory Nerve ◽  
Small Diameter ◽  
Nerve Fibers ◽  
Sensory Nerves ◽  
Upper Respiratory Tract ◽  
C Fibers ◽  
Afferent Nerves ◽  
Sensory Fibers ◽  
Peripheral Sensory

Itch is the most common chief complaint in patients visiting dermatology clinics and is analogous to cough and also sneeze of the lower and upper respiratory tract, all three of which are host actions trying to clear noxious stimuli. The pathomechanisms of these symptoms are not completely determined. The itch can originate from a variety of etiologies. Itch originates following the activation of peripheral sensory nerve endings following damage or exposure to inflammatory mediators. More than one sensory nerve subtype is thought to subserve pruriceptive itch which includes both unmyelinated C-fibers and thinly myelinated Aδ nerve fibers. There are a lot of mediators capable of stimulating these afferent nerves leading to itch. Cough and itch pathways are mediated by small-diameter sensory fibers. These cough and itch sensory fibers release neuropeptides upon activation, which leads to inflammation of the nerves. The inflammation is involved in the development of chronic conditions of itch and cough. The aim of this review is to point out the role of sensory nerves in the pathogenesis of cough and itching. The common aspects of itch and cough could lead to new thoughts and perspectives in both fields.

Neurophysiological effect of 3-cm microwave radiation

1961 ◽  
Vol 200 (2) ◽  
pp. 192-194 ◽  
Author(s):  
Robert D. McAfee
Keyword(s):  
Microwave Irradiation ◽  
Subcutaneous Tissue ◽  
Sensory Nerve ◽  
Nerve Fibers ◽  
Whole Body ◽  
Nociceptive Response ◽  
Small Areas ◽  
Sensory Fibers ◽  
Peripheral Sensory ◽  
Stimulation Of

Neurophysiological effects from locally applied 3-cm microwave irradiation are demonstrated on decerebrate and anesthetized cats and shown to be the result of thermal stimulation of peripheral sensory nerve fibers. The penetrating characteristic of 3-cm radiation heats these fibers within the skin and subcutaneous tissue to 45° ± 2°C at which temperature a nociceptive response is elicited from the experimental animals. The irradiation is applied to small areas of skin or short sections of nerve trunks rich in sensory fibers and the nociceptive response obtained is quite different from the signs of a hyperthermal state seen during whole-body microwave irradiation.

Role of Mechanoinsensitive Nociceptors in Painful Diabetic Peripheral Neuropathy

2021 ◽  
Vol 18 ◽  
Author(s):  
Mikhail I. Nemenov ◽  
Robinson J. Singleton ◽  
Louis S. Premkumar
Keyword(s):  
Peripheral Neuropathy ◽  
Diabetic Peripheral Neuropathy ◽  
Small Diameter ◽  
Clinical Settings ◽  
Fiber Types ◽  
Axon Reflex ◽  
Pain Thresholds ◽  
C Fibers ◽  
Painful Diabetic Peripheral Neuropathy

: The cutaneous mechanisms that trigger spontaneous neuropathic pain in diabetic peripheral neuropathy (PDPN) are far from clear. Two types of nociceptors are found within the epidermal and dermal skin layers. Small-diameter lightly myelinated Aδ and unmyelinated C cutaneous mechano and heat sensitive (AMH and CMH) and C mechanoinsensitive (CMi) nociceptors transmit pain from the periphery to central nervous system. AMH and CMH fibers are mainly located in the epidermis and CMi fibers are distributed in the dermis. In DPN, dying back intra-epidermal AMH and CMH fibers leads to reduced pain sensitivity and the patients exhibit significantly increased pain thresholds to acute pain, when tested using traditional methods. The role of CMi fibers in painful neuropathies has not been fully explored. Microneurography has been the only tool to access CMi fibers and differentiate AMH, CMH and CMi fiber types. Due to the complexity, its use is impractical in clinical settings. In contrast, a newly developed diode laser fiber selective stimulation (DLss) technique allows to safely and selectively stimulate Aδ and C fibers in the superficial and deep skin layers. DLss data demonstrate that patients with painful DPN have increased Aδ fiber pain thresholds, while C-fiber thresholds are intact because in these patients CMi fibers are abnormally spontaneously active. It is also possible to determine the involvement of CMi fibers by measuring the area of DLss-induced neurogenic axon reflex flare. The differences in AMH, CMH and CMi fibers allow to identify patients with painful and painless neuropathy. In this review, we will discuss the role of CMi fibers in PDPN.

scholarly journals Botulinum Toxin-A Therapy in Pediatric Urology: Indications for the Neurogenic and Non-Neurogenic Neurogenic Bladder

2009 ◽  
Vol 9 ◽  
pp. 1300-1305 ◽  
Author(s):  
Lori Dyer ◽  
Israel Franco
Keyword(s):  
Botulinum Toxin ◽  
Neurogenic Bladder ◽  
Botulinum Toxin A ◽  
Sensory Nerve ◽  
Nerve Fibers ◽  
Review Article ◽  
Pediatric Urology ◽  
Urethral Sphincter ◽  
Toxin A

Although, the role of Botulinum Toxin-A in the treatment of the neurogenic and non-neurogenic neurogenic bladder is becoming more defined, this is the first review article to characterize the emerging role of Botulinum Toxin-A in the pediatric urologic population. Injection of Botulinum Toxin-A at the level of the bladder works by inhibiting uninhibited bladder contractions and, possibly, by blocking some of the sensory nerve fibers. In children with sphincter dyssynergy, injection at the level of the urethral sphincter works by inhibiting the involuntary guarding reflex and blocking dyssynergic voiding.

Capsaicin-sensitive afferent nerves activate submucosal secretomotor neurons in guinea pig ileum

1995 ◽  
Vol 269 (2) ◽  
pp. G203-G209 ◽  
Author(s):  
S. Vanner ◽  
W. K. MacNaughton
Keyword(s):  
Guinea Pig ◽  
Ion Transport ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Sensory Nerve ◽  
Nerve Fibers ◽  
Sensory Nerves ◽  
Guinea Pig Ileum ◽  
Secretomotor Neurons

This study examined whether capsaicin-sensitive sensory nerves regulate intestinal ion transport using both Ussing chamber and intracellular recording techniques in in vitro submucosal preparations from the guinea pig ileum. In Ussing chamber studies, serosal application of capsaicin (20 nM-20 microM) evoked a biphasic dose-dependent increase in short-circuit current (Isc) (maximal effective concentration 200 nM and 2 microM, respectively). In chloride-free buffer, capsaicin responses were significantly reduced. Capsaicin evoked little or no response when extrinsic sensory nerve fibers had been surgically removed and tetrodotoxin and low-calcium and high-magnesium solutions blocked responses to capsaicin. In epithelial preparations devoid of submucosal neurons, capsaicin had virtually no effect, suggesting that responses evoked by capsaicin-sensitive nerves result from activation of submucosal secretomotor neurons. Intracellular recordings from single submucosal neurons demonstrated that superfusion with capsaicin (2 microM) depolarized neurons with an associated decreased conductance. Depolarizations were completely desensitized when capsaicin was reapplied, but synaptic inputs were unaffected. This study suggests that capsaicin-sensitive nerves can regulate ion transport in the gastrointestinal tract by release of neurotransmitter(s) that activate submucosal secretomotor neurons.

Relationships between permeable vessels, nerves, and mast cells in rat cutaneous neurogenic inflammation

1990 ◽  
Vol 68 (6) ◽  
pp. 2305-2311 ◽  
Author(s):  
J. N. Baraniuk ◽  
M. L. Kowalski ◽  
M. A. Kaliner
Keyword(s):  
Electrical Stimulation ◽  
Mast Cells ◽  
Neurogenic Inflammation ◽  
Sensory Nerve ◽  
Nerve Fibers ◽  
Sensory Nerves ◽  
Neurokinin A ◽  
Rat Skin ◽  
Protein Extravasation ◽  
Stimulation Of

Electrical stimulation of rat sensory nerves produces cutaneous vasodilation and plasma protein extravasation, a phenomenon termed “neurogenic inflammation”. Rat skin on the dorsum of the paw developed neurogenic inflammation after electrical stimulation of the saphenous nerve. In tissue sections, the extravasation of the supravital dye monastral blue B identified permeable vessels. Mast cells were identified by toluidine blue stain. Permeable vessels were significantly more dense in the superficial 120 microns of the dermis than in the deeper dermis, whereas mast cells were significantly more frequent in the deeper dermis. The relationships between nociceptive sensory nerve fibers, permeable vessels, and mast cells were examined by indirect immunohistochemistry for calcitonin gene-related peptide (CGRP), neurokinin A (NKA), and substance P (SP). CGRP-, NKA-, and SP-containing nerves densely innervated the superficial dermis and appeared to innervate the vessels that became permeable during neurogenic inflammation. In contrast, mast cells were not associated with either permeable vessels or nerve fibers. These data suggest that electrical stimulation of rat sensory nerves produces vascular permeability by inducing the release of neuropeptides that may directly stimulate the superficial vascular bed. Mast cells may not be involved in this stage of cutaneous neurogenic inflammation in rat skin.

Renal sympathetic nerve activity modulates afferent renal nerve activity by PGE2-dependent activation of α1- and α2-adrenoceptors on renal sensory nerve fibers

2007 ◽  
Vol 293 (4) ◽  
pp. R1561-R1572 ◽  
Author(s):  
Ulla C. Kopp ◽  
Michael Z. Cicha ◽  
Lori A. Smith ◽  
Jan Mulder ◽  
Tomas Hökfelt
Keyword(s):  
Sensory Nerve ◽  
Nerve Fibers ◽  
Sensory Nerves ◽  
Nerve Activity ◽  
Renal Nerve ◽  
Renal Sympathetic Nerve Activity ◽  
Pelvic Wall ◽  
Renal Nerve Activity ◽  
Pelvic Perfusion ◽  
Renal Sympathetic

Increasing efferent renal sympathetic nerve activity (ERSNA) increases afferent renal nerve activity (ARNA). To test whether the ERSNA-induced increases in ARNA involved norepinephrine activating α-adrenoceptors on the renal sensory nerves, we examined the effects of renal pelvic administration of the α1- and α2-adrenoceptor antagonists prazosin and rauwolscine on the ARNA responses to reflex increases in ERSNA (placing the rat's tail in 49°C water) and renal pelvic perfusion with norepinephrine in anesthetized rats. Hot tail increased ERSNA and ARNA, 6,930 ± 900 and 4,870 ± 670%·s (area under the curve ARNA vs. time). Renal pelvic perfusion with norepinephrine increased ARNA 1,870 ± 210%·s. Immunohistochemical studies showed that the sympathetic and sensory nerves were closely related in the pelvic wall. Renal pelvic perfusion with prazosin blocked and rauwolscine enhanced the ARNA responses to reflex increases in ERSNA and norepinephrine. Studies in a denervated renal pelvic wall preparation showed that norepinephrine increased substance P release, from 8 ± 1 to 16 ± 1 pg/min, and PGE2 release, from 77 ± 11 to 161 ± 23 pg/min, suggesting a role for PGE2 in the norepinephrine-induced activation of renal sensory nerves. Prazosin and indomethacin reduced and rauwolscine enhanced the norepinephrine-induced increases in substance P and PGE2. PGE2 enhanced the norepinephrine-induced activation of renal sensory nerves by stimulation of EP4 receptors. Interaction between ERSNA and ARNA is modulated by norepinephrine, which increases and decreases the activation of the renal sensory nerves by stimulating α1- and α2-adrenoceptors, respectively, on the renal pelvic sensory nerve fibers. Norepinephrine-induced activation of the sensory nerves is dependent on renal pelvic synthesis/release of PGE2.

TRPA1 in bradykinin-induced mechanical hypersensitivity of vagal C fibers in guinea pig esophagus

2009 ◽  
Vol 296 (2) ◽  
pp. G255-G265 ◽  
Author(s):  
Shaoyong Yu ◽  
Ann Ouyang
Keyword(s):  
Guinea Pig ◽  
Action Potentials ◽  
Transient Receptor Potential ◽  
Ex Vivo ◽  
Sensory Nerve ◽  
Sensory Nerves ◽  
Peripheral Sensitization ◽  
Nerve Terminals ◽  
Mechanical Hypersensitivity ◽  
C Fibers

Bradykinin (BK) activates sensory nerves and causes hyperalgesia. Transient receptor potential A1 (TRPA1) is expressed in sensory nerves and mediates cold, mechanical, and chemical nociception. TRPA1 can be activated by BK. TRPA1 knockout mice show impaired responses to BK and mechanical nociception. However, direct evidence from sensory nerve terminals is lacking. This study aims to determine the role of TRPA1 in BK-induced visceral mechanical hypersensitivity. Extracellular recordings of action potentials from vagal nodose and jugular neurons are performed in an ex vivo guinea pig esophageal-vagal preparation. Peak frequencies of action potentials of afferent nerves evoked by esophageal distension and chemical perfusion are recorded and compared. BK activates most nodose and all jugular C fibers. This activation is repeatable and associated with a significant increase in response to esophageal distension, which can be prevented by the B2 receptor antagonist WIN64338. TRPA1 agonist allyl isothiocyanate (AITC) activates most BK-positive nodose and jugular C fibers. This is associated with a transient loss of response to mechanical distensions and desensitization to a second AITC perfusion. Desensitization with AITC and pretreatment with TRPA1 inhibitor HC-030031 both inhibit BK-induced mechanical hypersensitivity but do not affect BK-evoked activation in nodose and jugular C fibers. In contrast, esophageal vagal afferent Aδ fibers do not respond to BK or AITC and fail to show mechanical hypersensitivity after BK perfusion. This provides the first evidence directly from visceral sensory afferent nerve terminals that TRPA1 mediates BK-induced mechanical hypersensitivity. This reveals a novel mechanism of visceral peripheral sensitization.

Tachykinins mediate hypocapnia-induced bronchoconstriction in guinea pigs

1989 ◽  
Vol 67 (6) ◽  
pp. 2454-2460 ◽  
Author(s):  
A. M. Reynolds ◽  
R. D. McEvoy
Keyword(s):  
Guinea Pig ◽  
Lung Volume ◽  
Circulatory Arrest ◽  
Dynamic Compliance ◽  
Sensory Nerves ◽  
Gas Mixture ◽  
Afferent Nerves ◽  
Induced Changes ◽  
Prior Administration

The aim of this study was to determine whether hypocapnia causes bronchoconstriction by releasing tachykinins (TKs) from C-afferent nerves in airways. Hypocapnia-induced bronchoconstriction (HIBC) was induced in anesthetized vagotomized guina pigs by ventilating lungs with a heated humidified hypocapnic gas mixture for 15 min after sudden circulatory arrest. The intensity of bronchoconstriction was assessed by calculating changes in dynamic compliance and by measuring the relaxation lung volume at the completion of experiments. Visualization of the airways by tantalum bronchography showed constriction of segmental bronchi with relative sparing of more proximal airways. Hypocapnia-induced bronchoconstriction was prevented by prior administration of salbutamol aerosol. Three experimental interventions were used to investigate the role of TKs in HIBC: 1) repeated capsaicin injections to deplete airway sensory nerves of TKs, 2) treatment with phosphoramidon, an inhibitor of enkephalinase, the main enzyme responsible for TK inactivation, and 3) topical airway anesthesia. Capsaicin pretreatment markedly attenuated the hypocapnia-induced changes in dynamic compliance (P less than 0.0005) and relaxation lung volume (P less than 0.0002), whereas phosphoramidon augmented these changes (P less than 0.02, P less than 0.03, respectively). Topical anesthesia of airways with lignocaine postponed the onset of bronchoconstriction, whereas the longer-acting, more lipid-soluble local anesthetic, bupivacaine, almost completely prevented HIBC. We conclude that, in the guinea pig lung, HIBC is mediated by TKs that are released after the activation of bronchial axonal reflexes.

Sensory nerve- and neuropeptide-mediated relaxation responses in airways of Sprague-Dawley rats

1995 ◽  
Vol 78 (5) ◽  
pp. 1679-1687 ◽  
Author(s):  
J. L. Szarek ◽  
N. L. Stewart ◽  
B. Spurlock ◽  
C. Schneider
Keyword(s):  
Sensory Nerve ◽  
Electrical Field Stimulation ◽  
Sensory Nerves ◽  
Adrenergic Blockade ◽  
Sprague Dawley ◽  
Mechanically Ventilated ◽  
Sprague Dawley Rats ◽  
Calcitonin Gene ◽  
Relaxation Responses

We examined the role of sensory nerves in mediating nonadrenergic inhibitory responses in airway segments isolated from male Sprague-Dawley rats. In the presence of adrenergic blockade, capsaicin (Cap; 1 microM) elicited marked relaxation responses in isolated bronchi precontracted with bethanechol (Beth). Cap-induced inhibitory responses were unaffected by tetrodotoxin (TTX), were attenuated by incubation of the airway with indomethacin (Indo), phosphoramidon, or RP-67580, but were abolished by previous exposure of the airway to Cap and by denuding the epithelium. Substance P (SP; 1 microM), neurokinins A and B (1 microM), and calcitonin gene-related peptide (0.1 microM) relaxed Beth-contracted airway segments to a similar extent. The SP-induced responses were unaffected by adrenergic blockade or by pretreatment with either TTX, phosphoramidon, or Cap, but were attenuated by RP-67580 and abolished by Indo and by denuding the epithelium. In anesthetized mechanically ventilated rats, Cap (50 and 100 micrograms/kg i.v.) elicited a dose-dependent reversal of the increase in lung resistance induced by an infusion of Beth. The Cap-induced bronchodilation was unaffected by pretreatment with propranolol alone or in combination with hexamethonium. SP (44 nmol/kg iv) also evoked bronchodilatory responses in intact animals, which were unaffected by propranolol and hexamethonium but were abolished by treatment of the animals with Indo. Electrical-field stimulation (EFS) evoked nonadrenergic noncholinergic relaxation responses in contracted airway segments. These EFS-induced inhibitory responses were markedly attenuated by treatment of the airway segment with TTX, Cap, or RP-67580. We conclude that neuropeptides released from Cap-sensitive sensory nerves have potent inhibitory effects in rat airways that are mediated, in part, by activation of neurokonin NK1 receptors on epithelium and subsequent release of an inhibitory prostaglandin(s).

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