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PubMed2003

5-Hydroxytryptamine (5-HT)2 receptor involvement in acute 5-HT-evoked scratching but not in allergic pruritus induced by dinitrofluorobenzene in rats.

We investigated the role of serotonin (5-hydroxytryptamine; 5-HT)2 and 5-HT3 receptor subtypes in acute itch-associated scratching behavior as well as in an allergic pruritus model in rats. Intradermal 5-HT evoked hind limb scratching directed toward the injection site in naïve rats. Scratching behavior was significantly reduced by pretreatment with the 5-HT2 receptor antagonist ketanserin. Intradermal injection of alpha-methylserotonin, a 5-HT2 receptor agonist, also elicited scratching behavior in a dose-dependent manner, indicating that acute 5-HT-induced scratching is mediated via peripheral 5-HT2 receptors. To produce a model of allergic pruritus, skin was sensitized by topical application of 5% dinitrofluorobenzene (DNFB). One month later, repeated challenge of the skin with 0.2% DNFB at weekly intervals elicited scratching as part of the immediate allergic response. Scratching was not affected by ketanserin or by the 5-HT3 receptor antagonist ondansetron, indicating that neither 5-HT2 nor 5-HT3 receptors is involved in itch-associated scratching behavior caused by allergic skin dermatitis in rats.

Animals↗

PubMed1997

Spinal cord coordination of hindlimb movements in the turtle: interlimb temporal relationships during bilateral scratching and swimming.

Hindlimb interlimb coordination was examined in turtles during symmetrical "same-form" behaviors in which both hindlimbs utilized the same movement strategy ("form") and during asymmetric "mixed-form" behaviors in which the form exhibited by one hindlimb differed from that of its contralateral partner. In spinal turtles, three forms of scratching were examined: rostral, pocket, and caudal. Bilateral symmetrical same-form scratching was studied for each of the forms. Asymmetric mixed-form scratching (rostral scratching of a hindlimb and pocket scratching of the other hindlimb) was also examined. In intact turtles, two forms of swimming were examined: forward swimming and back-paddling. The symmetrical behavior of bilateral forward same-form swimming and the asymmetric behavior of turning mixed-form swimming (forward swimming of 1 hindlimb and back-paddling of the other hindlimb) were studied. For all behaviors examined, most episodes displayed absolute or 1:1 coordination; in this type of coordination, during each movement cycle that began and ended with the onset of ipsilateral hip flexion, there was a single onset of contralateral hip flexion. For most of these episodes there was out-of-phase coordination between hip movements; the onset of contralateral hip flexion occurred near the onset of ipsilateral hip extension midway through the ipsilateral movement cycle. Bilateral caudal/caudal same-form scratching displayed out-of-phase 1:1 coordination during some episodes and in-phase 1:1 coordination during other episodes. During in-phase coordination, the onset of contralateral hip flexion occurred near the onset of ipsilateral hip flexion close to the start of the ipsilateral movement cycle. In a few cases of bilateral same-form scratching there were episodes of relative or 2:1 coordination; in this type of coordination, during each movement cycle of the slowly moving limb that began and ended with ipsilateral hip flexion, there were two distinct occurrences of the onset of contralateral hip flexion. The observation that out-of-phase movements of the hip occurred during symmetrical as well as asymmetric behaviors is consistent with the hypothesis that timing signals related to hip movement play a major role in interlimb phase control. The neural mechanisms responsible for interlimb phase control are not well understood in vertebrates. The present demonstration of bilateral scratching in spinal turtles suggests that this preparation may be suitable for additional experiments to examine mechanisms of vertebrate interlimb phase control.

Animals↗

PubMed1998

Modulation of oligosynaptic cutaneous and muscle afferent reflex pathways during fictive locomotion and scratching in the cat.

We have compared state-dependent transmission through oligosynaptic (minimally disynaptic) reflex pathways from low-threshold cutaneous and muscle afferents to some flexor and extensor lumbosacral motoneurons during fictive locomotion and scratching in decerebrate unanesthetized cats. As reported in earlier work, oligosynaptic cutaneous excitatory postsynaptic potentials (EPSPs) in flexor digitorum longus (FDL) and inhibitory postsynaptic potentials (IPSPs) in extensor digitorum (EDL) longus motoneurons were enhanced markedly during the early flexion phase of fictive locomotion. We show in this paper that, in contrast, these cutaneous reflex pathways were depressed markedly during all phases of fictive scratching. On the other hand, disynaptic EPSPs produced by homonymous and synergist group I muscle afferents in flexor (tibialis anterior and EDL) motoneurons were present and strongly modulated during both fictive locomotion and scratching. During both actions, these disynaptic group I EPSPs appeared or exhibited the largest amplitude when the motoneuron membrane potential was most depolarized and the parent motor pool was active. There was an interesting exception to the simple pattern of coincident group I EPSP enhancement and motoneuron depolarization. During locomotion, disynaptic group I EPSPs in both FDL and flexor hallucis longus (FHL) motoneurons cells were facilitated during the extension phase, although FDL motoneurons were relatively hyperpolarized whereas FHL cells were depolarized. The reverse situation was found during fictive scratching; group I EPSPs were facilitated in both FDL and FHL cells during the flexion phase when FDL motoneurons were depolarized and FHL cells were relatively hyperpolarized. These observations suggest that the disynaptic EPSPs in these two motor nuclei are produced by common interneurons. Reciprocal disynaptic inhibitory pathways from group Ia muscle afferents to antagonist motoneurons were also active and subject to phase-dependent modulation during both fictive locomotion and scratching. In all but one cell tested, reciprocal disynaptic group Ia IPSPs were largest during those phases in which the motoneuron membrane potential was relatively hyperpolarized and the parent motor pool was inactive. Oligosynaptic PSPs in motoneurons produced by stimulation of the mesencephalic locomotor region (MLR) were modulated strongly during fictive locomotion but were suppressed powerfully throughout fictive scratching. Large cord dorsum potentials generated by MLR stimuli also were suppressed markedly during fictive scratching. These results allow certain inferences about the organization of interneurons in the pathways examined. They also suggest that the central pattern generators that produce fictive locomotion and scratching are organized differently.

Afferent Pathways↗

PubMed1999

Reciprocal interactions in the turtle hindlimb enlargement contribute to scratch rhythmogenesis.

We examined interactions between the spinal networks that generate right and left rostral scratch motor patterns in turtle hindlimb motoneurons before and after transecting the spinal cord within the anterior hindlimb enlargement. Our results provide evidence that reciprocal inhibition between hip circuit modules can generate hip rhythmicity during the rostral scratch reflex. "Module" refers here to the group of coactive motoneurons and interneurons that controls either flexion or extension of the hip on one side and coordinates that activity with synergist and antagonist motor pools in the same limb and in the contralateral limb. The "bilateral shared core" hypothesis states that hip flexor and extensor (HF and HE) circuit modules interact via crossed and uncrossed spinal pathways: HF modules make reciprocal inhibitory connections with contralateral HF and ipsilateral HE modules and mutual excitatory connections with contralateral HE modules. It is currently unclear how much reciprocal inhibition between modules contributes to scratch rhythmogenesis. To address this issue, fictive scratch motor patterns were recorded bilaterally as electroneurograms from HF, HE, knee extensor (KE), and respiratory (d.D8) muscle nerves in immobilized animals. D3-end (low-spinal) preparations had intact spinal cords posterior to a complete D2-D3 transection. Unilateral stimulation of rostral scratch in D3-end turtles elicited rhythmic alternation between ipsilateral HF and HE bursts in most cycles; consecutive HF bursts were separated by complete silent (HF-OFF ) periods. D3-D9 and D3-D8 preparations received a second spinal transection at the caudal end of segment D9 or D8, respectively, within the anterior hindlimb enlargement. This second transection disconnected most HE circuitry (located mainly in segments D10-S2 of the posterior enlargement) from the rostral scratch network and thereby reduced the HE-associated inhibition of HF circuitry. Unilateral stimulation of rostral scratch in most D3-D9 and D3-D8 preparations evoked rhythmic or weakly modulated ipsilateral HF discharge without HF-OFF periods between bursts and without ipsilateral HE activity in the majority of cycles. In contrast, bilateral stimulation in D3-D9 and D3-D8 preparations reconstructed the HF-OFF periods, increased HF rhythmicity (assessed by fast Fourier transform power spectra and autocorrelation analyses), and reestablished weak HE-phase motoneuron activity. We suggest that bilateral stimulation produced these effects by simultaneously activating reciprocally inhibitory hip modules on opposite sides (right and left HF) and the same side (HF and residual ipsilateral HE circuitry). Our data support the hypothesis that reciprocal inhibition can contribute to spinal rhythmogenesis during the scratch reflex.

Animals↗

PubMed1990

[The restructuring of the efferent activity of the generator of scratching during the electrical activation of the descending systems].

Rearrangement of the scratching generator activity evoked by phasic electrical stimulation of different descending systems has been investigated on decerebrated immobilized cats. This rearrangement heavily depends on the stimulation phase. Maximal increase of the scratching cycle duration by electrical stimulation of Deiters' nucleus, red nucleus and pyramidal tract takes place in the first half of an aiming phase. The electrical stimulation of structures mentioned above does not practically change duration of the scratching cycle in the second half of the aiming phase and at the beginning of the scratching phase. A maximal increase of the scratching cycle duration by electrical stimulation of reticular gigantocellular nucleus occurs in the second half of the aiming phase. The electrical activation of descending pathways during the aiming phase increases intensity of this phase and decreases intensity of the scratching phase. The electrical activation of descending pathways during the scratching phase increases its intensity and does not change practically the intensity of the aiming phase. Possible principles of the suprasegmental correction of the scratching generator activity are discussed.

Animals↗

PubMed1999

Cat-scratch neuroretinitis.

BACKGROUND: Cat-scratch disease is a subacute regional lymphadenitis, usually preceded by a history of a cat scratch or exposure to kittens. The disease is caused by Bartonella henselae, and possibly Bartonella quintana, pleomorphic gram-negative rods formerly known as Rochalimaea henselae and Rochalimaea quintana. Ocular involvement is rare and typically manifests as either Parinaud's oculoglandular syndrome or neuroretinitis. Patients with neuroretinitis resulting from cat-scratch disease may be asymptomatic or experience mild-to-severe vision loss. The clinical features, angiographic appearance, differential diagnosis, and management of cat-scratch neuroretinitis are discussed. CASE REPORT: A 30-year-old white woman reported to the eye clinic with painless, decreased vision in the right eye. A diagnosis of cat scratch neuroretinitis was made on the basis of the history of cat scratch, clinical appearance, and angiographic findings. Treatment with oral ciprofloxacin restored vision to normal in 4 weeks. CONCLUSION: Painless vision loss associated with optic nerve swelling and macular star exudate should alert suspicion of systemic disease. Additional findings--including positive history of a cat scratch, lymphadenopathy, and flu-like symptoms--may indicate Bartonella henselae or Bartonella quintana infection. While treatment remains controversial, appropriate serology testing may aid in the diagnosis and management of the underlying infection.

Bartonella henselae↗

PubMed1988

Pruritic rash associated with cat scratch disease.

Cat scratch disease is a benign, self-limited illness characterized by regional lymphadenopathy that usually occurs in association with a history of contact with a cat. Cases of cat scratch disease with skin manifestations that included erythema nodosum; erythema multiforme; erythema marginatum; and non-specific maculopapular, petechial, and morbilliform rashes have been reported. No case of pruritic rash associated with cat scratch disease has been previously reported. In fact, one authority specifically states that the rash of cat scratch disease is nonpruritic. We report a well-documented case of cat scratch disease in which the patient's principal symptom was a pruritic rash. It is possible that this rash was the result of an immunologic reaction to the infectious agent of cat scratch disease. We conclude that cat scratch disease should be included in the differential diagnosis of pruritic rashes in children.

Cat-Scratch Disease↗

PubMed1999

Contact guidance of chick embryo neurons on single scratches in glass and on underlying aligned human skin fibroblasts.

The influence of substratum topography on the morphology and orientation of neurites of chick embryo neurons was studied. Two series of experiments are reported. One concerned the behaviour of growth cones when the axons become contact-guided by the surface texture. The second studied contact guidance of neurites extending on a compact layer of fixed aligned human skin fibroblasts (HSF). It was observed that when the growth cones of sensory neurons isolated from dorsal root ganglions encountered a single scratch in a glass surface (0.1-2 microm in depth and diameter) they turned and continued movement following the axis of the scratch. These neurons became contact-guided as a result of the sequence of events. The growth cone filopodia recognized the irregularity in the substratum surface, whereas the growth cone lamella stabilized contact with the scratch and moved forward along the scratch axis. Scanning electron microscope revealed that the single scratches 150 nm in width and ca. 100 nm deep growth cone filopodia less than 200 nm in diameter could detect and react by turning into them. These filopodia extensions followed the edge of scratches. However, phase contrast and Nomarski's differential interference contrast appeared insufficient for analysis of primary contact guidance of fine growth cone filopodia which themselves are often less than 200 nm. In neuron cultures on fixed aligned HSF, the neuron aggregates assumed spindle-like shapes, and sparsely seeded individual neurons extended axons along the long axes of the fibroblasts. The axons extended significantly further on the fixed underlying fibroblasts than on collagen-covered glass. In crowded cultures of neurons, the cells extended neurites ignoring both the surface anisotropy (the scratches) and the orientation of the aligned fibroblasts. Immunofluorescence staining of neurons with antibodies against neurofilaments made it possible to analyse their shape and orientation on the fibroblasts. Computer-assisted image analysis permitted the observed alignment of the neurites to be characterized quantitatively.

Animals↗

PubMed1975

On the role of central program and afferent inflow in the control of scratching movements in the cat.

Rhythmical scratching movements of the hindlimb were evoked in decerebrate and decapitate cats by stimulation of C1-C2 segments of the spinal cord. Movements of the limb and electrical activity of its muscles were recorded. All muscles were divided into two groups according to their activity. Muscles of the first group supported the limb in a propriate position; they were active during most of the cycle and relaxed during small intervals when muscles of the second group contracted. A deafferented limb was also capable of rhythmical scratching movements with approximately the same cycle duration. However, after deafferentation, the mean position of the limb changed and the amplitude of oscillations increased. This is due mainly to decreased activity of the first group muscles. In curarized preparations, stimulation of C1-C2 segments evoked a rhythmical process within the lumbosacral spinal cord ('fictive' scratching) with a cycle duration nearly the same as in normal scratching. Electrical activity of the muscle nerves during 'fictive' scratching resembled that of corresponding muscles during normal movements. 'Fictive' scratching could be easily elicited provided that the limb was put in a position similar to that of normal scratching.

Animals↗

PubMed1978

Messages conveyed by descending tracts during scratching in the cat. II. Activity of rubrospinal neurons.

(1) The activity of rubrospinal (RS) neurons giving axons to the lumbosacral spinal cord was recorded during actual and fictitious8 scratching in thalamic cats. (2) During both actual and fictitious scratching, the discharge frequency of many RS neurons was rhythmically modulated. Different neurons were active in different parts of the scratch cycle, but most neurons were active in the flexor phase. (3) The discharge frequency within the bursts during fictitious scratching was, on the average, equal to that during actual scratching. Immobilization usually resulted only in a small displacement of the burst position in the scratch cycle. Therefore, rhythmical modulation of RS neurons is determined mainly by central mechanisms and not by a rhythmical sensory input. (4) In decerebellate cats, the overwhelming majority of RS neurons had no rhythmical modulation. Very weak modulation was found only in a few neurons. (5) Transection of the ventral spinocerebellar tract (VSCT) resulted in considerable reduction or complete cessation of rhythmical modulation in RS neurons during fictitious scratching. On the contrary, transection of the spino-reticulocerebellar pathway (SRCP) resulted in just a small decrease of modulation. Therefore, of the two pathways (the VSCT and SRCP) transmitting messages about intraspinal processes to the cerebellum during scratching2,3, the VSCT is of major importance for modulating RS neurons.

Animals↗

PubMed1980

Activity of neurons of cerebellar nuclei during fictitious scratch reflex in the cat. II. Interpositus and lateral nuclei.

The activity of neurons of the interpositus and lateral cerebellar nuclei was recorded during fictitious scratch reflex in thalamic cats immobilized with Flaxedil. Interpositus neurons were identified by antidromic response to stimulation of the contralateral red nucleus. The interpositus neurons responding to passive movements of the ipsilateral hindlimb manifested rhythmical modulation of the discharge in relation with the scratch cycle. The neurons generated bursts of impulses separated by periods of silence. Different neurons were active in different parts of the scratch cycle, but most of them were active in the second half of the flexor phase. When the scratch reflex was evoked on the contralateral side, rhythmical modulation was observed in about half of the neurons, and it was less pronounced than in the case of ipsilateral scratching. Rhythmical modulation of cerebellar neurons during fictitious scratching is determined by signals coming from the central spinal mechanism, generating rhythmical oscillations, via the ventral spinocerebellar tract (VSCT) and the spinoreticulocerebellar pathway (SRCP). Results of separate transections of these pathways showed that the VSCT plays the crucial role in modulating interpositus neurons. Neurons of the lateral nucleus exhibited no modulation during fictitious scratching.

Afferent Pathways↗

PubMed2003

Endogenous glucocorticoids inhibit scratching behavior induced by the administration of compound 48/80 in mice.

In this study, we investigated the effects of endogenous glucocorticoids on the compound 48/80 (a condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde)-induced mouse scratching behavior using either RU-486 (mifepristone), a glucocorticoid receptor antagonist, or a surgical resection of the adrenal glands. Subcutaneous injection of compound 48/80 induced not only a corticosterone elevation in the plasma but also an enhanced expression of corticotropin releasing hormone (CRH) mRNA in the paraventricular nucleus, which thus suggests that hypothalamic-pituitary-adrenal axis is activated by the compound 48/80-induced cutaneous reaction. Inhibition of such an endogenous glucocorticoid activity by RU-486 significantly increased the degree of scratching behavior at not only the early-phase (<60 min) but also the late-phase (>60 min) time course after the injection of compound 48/80. Since the elevation of the histamine levels in the plasma in the RU-486-treated mice was no longer found in late-phase scratching behavior, these results thus indicate that histamine is a dominant mediator responsible for early-phase scratching behavior, while different mediators other than histamine may be also involved in the induction of late-phase scratching behavior. Moreover, surgical removal of adrenal glands also significantly increased the compound 48/80-induced scratching behavior without affecting anxiety and locomotor parameters, indicating that endogenous glucocorticoids exert their anti-pururitogenic effects independently of changes in behavioral performance. In conclusion, endogenous glucocorticoid activity was found to suppress the compound 48/80-induced scratching behavior in mice.

Adrenalectomy↗

PubMed2006

Comparison of scratching behaviour of growing pigs with sarcoptic mange before and after treatment, employing two distinct approaches.

In a closed pig breeding and finishing herd suffering from sarcoptic mange, two selected groups of pigs were filmed during a period of 10 days before and after treatment. The observation always commenced each hour and lasted for 15 min. Before treatment, observations was done round the clock, after treatment from 8:00 to 22:15. Before treatment the pens were stocked with 11 (pen A) and 10 (pen B) growing pigs (Large WhitexLandrace sows; 5 months old) with an average weight of approximately 70 kg examined for sarcoptic mange by skin scrapings and ELISA. The animals had never been treated with an acaricide or endectocide before. After 10 days, the pigs were treated twice (18 days interval) with Dectomax 1% solution for pigs (Pfizer, Austria) at a dose of 0.3 mg Doramectin i.m./kg body weight. After treatment, seven pigs were observed in both pens. Most scratching actions both before (83.1%) and after (94.5%) treatment were of one to 10 s. After treatment, the 10 s-scratching episodes decreased by 67.3% (from 21.2 to 6.9 mean SRE/pig), and the scratching actions of longer than 10 s by 91.7% (from 4.3 to 0.4 mean SRE/pig), such that the latter could be observed only occasionally after treatment. A distinct increase in scratching activity both before and after treatment could be observed primarily between 10:00 and 15:00. Significant differences of scratching and rubbing activity between before and after treatment could also be seen at midday. The interpretation of the scratching index values before and after the treatment were carried out according to Cargill et al. [Cargill, C., Davies, P., Carmichael, I., Hooke, F., Moore, M., 1994. Treatment of pigs with doramectin to control sarcoptic mange. Proceedings of the 13th IPVS Congress, Bangkok, Thailand, p. 238] with the maximum and minimal limiting values specified in the literature, and compared with calculations using the method described by Hollanders et al. [Hollanders, W., Harbers, A.H.M., Huige, J.C.M., Monster, P., Rambags, P.G.M., Hendrikx, W.M.L., 1995. Control of Sarcoptes scabiei var. suis with ivermectin: influence on scratching behaviour of fattening pigs and occurence of dermatitis at slaughter. Vet. Parasitol. 58, 117-127]. Depending on the methods used and the limiting values set, 6.7-34.6% of the observations before and 2.0-17.3% of the observations after treatment revealed a "strong evidence of mange" or a "suspicion of mange". All other observations indicated that the pigs were free from mange.

Animals↗

PubMed1991

Feline scratching and destruction and the effects of declawing.

Scratching is an inherited, normal behavior in cats that is used as a visual and olfactory territorial mark and as a stretching exercise for the forelegs. In addition, it serves to condition the claws by removing the old, worn-out external sheath and exposing the healthy, new claw. When scratching occurs indoors, it often is disruptive and undesirable unless it can be directed to an acceptable object such as a scratching post. During playing, jumping, climbing, and aggressive displays, cats also may injure people with their claws. With appropriate behavior modification techniques, most undesirable scratching can be prevented or eliminated. Although somewhat controversial, declawing is another alternative for those owners who are unwilling or unable to control the undesirable scratching. Declawing can successfully correct most scratching problems with no adverse behavioral effects; in fact, most owners of declawed cats indicate that there is an improved relationship (bonding) between cat and owner. On the other hand, declawing is often unnecessary, because appropriate behavior modification techniques can be used to correct most scratching problems successfully.

Animals↗

PubMed2003

Skin scratching switches immune responses from Th2 to Th1 type in epicutaneously immunized mice.

BACKGROUND: The balance between Th1 and Th2 subsets is important with respects to susceptibility and resistance to particular infection or autoimmune diseases. However, the mechanism controlling Th1/Th2 balance remains unclear, although several factors have been reported to induce Th1/Th2 differentiation. Atopic Dermatitis (AD) that is a chronic skin disorder has been known as Th2 biased nature characterized by high expression of IgE in the serum. In contrast, the chronic skin lesions express IFNgamma and some patients don't show IgE in the serum. Thus, the pathology is also complicated now. OBJECTIVE: We focused on skin scratching that is common feature in the patients. In this study, we investigated in order to determine whether skin scratching regulates immune responses in murine epicutaneous sensitization model. METHODS: The scratched mice on abdominal skin using wire brush were applied with keyhole limpet hemocyanin (KLH) on the skin using occlusive patch. We examined the immune responses including delayed type hypersensitivity (DTH) reaction, antigen-specific serum immunoglobulin formation, and cytokine expressions on the local skin in comparison with mice without scratching. RESULTS: We found that the epicutaneously sensitized mice with KLH on abdominal skin showed Th2 biased immune response including expression of antigen-specific IgE in the serum and IL-13 in the local skin. Surprisingly, scratching on local abdominal skin using wire brush exchanged the immune response from Th2 dominance to Th1, because the mice displayed DTH reaction and significant level of antigen-specific IgG2a and IgG2b but not IgE in the serum. Furthermore, the abdominal skin showed significant level of IFNgamma but not IL-13. CONCLUSION: These data demonstrate that skin scratching switches immune response from Th2 biased response to Th1. This suggests that skin scratching play critical roles as one of exogenous immune modulator. This murine sensitization model may help to understand natures of several allergic disorders including AD.

Abdomen↗

PubMed1999

Reduction of sodium deoxycholic acid-induced scratching behaviour by bradykinin B2 receptor antagonists.

1. Subcutaneous injection of sodium deoxycholic acid into the anterior of the back of male ddY mice elicited dose-dependent scratching of the injected site with the forepaws and hindpaws. 2. Up to 100 microg of sodium deoxycholic acid induced no significant increase in vascular permeability at the injection site as assessed by a dye leakage method. 3. Bradykinin (BK) B2 receptor antagonists, FR173657 and Hoe140, significantly decreased the frequency of scratching induced by sodium deoxycholic acid. 4. Treatment with aprotinin to inhibit tissue kallikrein reduced the scratching behaviour induced by sodium deoxycholic acid, whereas treatment with soybean trypsin inhibitor to inhibit plasma kallikrein did not. 5. Although injection of kininase II inhibitor, lisinopril together with sodium deoxycholic acid did not alter the scratching behaviour, phosphoramidon, a neutral endopeptidase inhibitor, significantly increased the frequency of scratching. 6. Homogenates of the skin excised from the backs of mice were subjected to gel-filtration column chromatography followed by an assay of kinin release by trypsin from each fraction separated. Less kinin release from the fractions containing kininogen of low molecular weight was observed in the skin injected with sodium deoxycholic acid than in normal skin. 7. The frequency of scratching after the injection of sodium deoxycholic acid in plasma kininogen-deficient Brown Norway Katholiek rats was significantly lower than that in normal rats of the same strain, Brown Norway Kitasato rats. 8. These results indicate that BK released from low-molecular-weight kininogen by tissue kallikrein, but not from high-molecular-weight kininogen by plasma kallikrein, may be involved in the scratching behaviour induced by the injection of sodium deoxycholic acid in the rodent.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2001

Use of a wrist activity monitor for the measurement of nocturnal scratching in patients with atopic dermatitis.

BACKGROUND: The amount of nocturnal scratching can be an indirect correlate of itch in pruritic dermatoses. We have previously used an infrared video camera to measure nocturnal scratching in atopic dermatitis (AD). Although this is a reliable method of measuring nocturnal scratching, it is not suitable for routine monitoring in clinical use. OBJECTIVES: To find a simplified way of monitoring itch. METHODS: We tried using a wrist activity monitor (ActiTrac) for the measurement of nocturnal scratching in patients with AD. ActiTrac is a wristwatch-shaped device that contains a piezoceramic sensor to measure and record limb movement over a pre-set time interval. The acceleration signal produced by motion of the hands is stored and downloaded into a personal computer. The average value of acceleration (AVA, 10(-3) g min(-1)) was calculated and compared with total scratching time as a percentage of total recording time (TST%) measured with the use of an infrared video camera in 63 recordings of 21 patients with AD. For 261 recordings in 29 patients with AD, the AVA was measured and correlated with disease severity, and compared with the AVA of five non-itchy controls. RESULTS: There was a significant correlation between the AVA and TST% (r = 0.91, P < 0.001), and a regression equation of y = 0.44x - 2.5 was obtained. The AVA correlated well with the severity of AD and definitely differed from the results observed in normal controls. The AVA (mean +/- SD) was 44.4 +/- 19.1 for 115 recordings in patients with severe AD, 23.2 +/- 10.9 for 89 recordings in patients with moderate AD, 8.9 +/- 6.0 for 57 recordings in patients with mild AD and 4.1 +/- 1.9 for 25 recordings in five normal controls. The units used here are arbitrary units min-1 with a range of 0--250, which corresponds to 0-75 x 10(-6) g min(-1). CONCLUSIONS: A wrist activity monitor is able to measure nocturnal scratching. However, further methods of analysis should be sought to select scratching activity exclusively.

Adolescent↗

PubMed1999

Does lichen sclerosus play a central role in the pathogenesis of human papillomavirus negative vulvar squamous cell carcinoma? The itch-scratch-lichen sclerosus hypothesis.

In the past decade, two types of vulvar squamous cell carcinoma (SCC) have been delineated, Human papillomavirus (HPV) positive and negative. Clinicopathologic, virologic, cytomorphometric, and genetic differences support the view that these two types of carcinoma are fundamentally different and that HPV-negative carcinoma is not simply carcinoma where viral DNA has not been able to be identified. The traditional view of HPV-negative carcinoma is that it is caused by chronic tissue damage from itching and scratching. However, itching and scratching alone do not explain the close association of carcinoma with lichen sclerosus, nor the absence of such an association with other itchy conditions such as eczema or psoriasis. These observations point to a role for lichen sclerosus in the pathogenesis of vulvar carcinoma. Most observations about the etiology of lichen sclerosus can be grouped into its immunogenetic or genital predisposition, or the Köbner phenomenon. In the itch-scratch-lichen sclerosus hypothesis, lichen sclerosus is postulated to occur as a Köbner phenomenon in women with the susceptible immunophenotype who scratch because of genital irritants such as urine, vaginal secretions and smegma, and psychological factors. Lichen sclerosus, itself a very itchy condition, contributes to a vicious cycle of itching and scratching which leads to superimposed lichen simplex chronicus, squamous cell hyperplasia, and ultimately carcinoma. The itch-scratch-lichen sclerosus hypothesis reconciles the traditional itch-scratch hypothesis with the strong clinicopathologic association of lichen sclerosus with carcinoma.

Journal Article↗