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Query: UMLS:C0162473 (Frey)
 2,599 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This single fiber study on rat tail nerve afferents attempts to establish a peripheral neural correlate for the hyperalgesia to mechanical stimulation which follows injury to the skin. Mechano-heat sensitive C fibers (MH-C or "polymodal" nociceptors) and high-threshold mechanoreceptive A delta fibers (HTM-A delta) were examined with a series of constant noxious pressure stimulations (4-6-8-4 N on 25 mm2, 120 s each, 5 min intervals). These injurious stimuli were either directed to the most sensitive spot of the receptive fields (central stimulation) or closely outside their borders (1-5 mm). With this protocol no clear sensitization was seen in MH-C fibers apart from a stronger dynamic response to central stimulation in some of them. In contrast, most HTM-A delta units, irrespective of the site of noxious stimulation, developed spontaneous activity, lowering of their von Frey thresholds and expansion of their receptive fields. All HTM-A delta units responded to outside stimulation: upon the first stimulus (4 N) there was a delayed discharge of continuously increasing frequency ("recruited response"), but the onset of the last stimulation (4 N repeated) evoked vigorous dynamic responses in many fibers. The recruitment of HTM-A delta nociceptor activity may contribute to post-injury hyperalgesia to mechanical stimulation and it may counteract adaptation of the single afferent fiber during prolonged noxious influence.
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PMID:Sensitization of nociceptive cutaneous nerve fibers from the rat's tail by noxious mechanical stimulation. 355 78

1. Cholinergic effects on primary sensory afferents were investigated in a superfused skin-saphenous nerve preparation of the rat that allows the application of chemicals topically to the corium side of identified receptive fields. 2. The acetylcholine analogue carbachol (carbamoylcholine) selectively excited cutaneous C-fibers of nociceptive character; in proportion, almost half of the mechanoheat sensitive ("polymodal," C-MH, n = 27), and a third of the mechanocold sensitive (C-MC, n = 10), and high-threshold mechanosensitive (C-HTM, n = 6) C-fibers were activated. 3. None of slowly and rapidly adapting A beta fibers, low and high threshold mechanoreceptive A delta fibers (n = 19) gave a response to high concentrations (< or = 10(-4) M) of carbachol. 4. The carbachol threshold concentrations of C-nociceptors ranged between 10(-7) and 10(-4) M; 10(-6) M was most frequently encountered. 5. The carbachol-induced discharges showed a dose-response relationship without obvious "ceiling" from 10(-6) to 10(-4) M. Tachyphylaxis was not prominent; the fibers mostly developed ongoing activity after exposure to carbachol. 6. Repeated carbachol treatment of C-MH units left with a marked and sustained desensitization to mechanical (von Frey) stimulation, while the heat responsiveness remained unchanged. 7. In a group of carbachol-sensitive C-nociceptors (n = 4), two units could also be excited with muscarine (10(-6) M), one with nicotine (10(-6) M), and one unit with both substances.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Actions of cholinergic agonists and antagonists on sensory nerve endings in rat skin, in vitro. 810 89

Characteristics of mucosal nociceptors were investigated by recording activities from single fibers in the lingual nerve in an in vitro jaw-nerve preparation of rats. We found four subtypes of nociceptors in the medial side gingival area of the oral mucosa in the lower jaw: 11 A delta-high threshold mechanonociceptors (A delta-HTMs), 7 A delta-mechanoheat nociceptors (A delta-MHs), 21 A delta-polymodal nociceptors (A delta-POLYs) and 28 C-polymodal nociceptors (C-POLYs). Thus the majority of the nociceptors was polymodal type (ca. 73% of the recorded fibers), ca. 43% of which consisted of A delta-POLYs scarcely found in the skin but commonly found in the deep tissue, muscle or colon. In contrast to the skin, the size of the receptive field of both A delta and C polymodal types was larger than that of either A delta-HTM or A delta-MH type. The von Frey threshold of all types of mucosal nociceptor was higher than that of the skin, though their heat threshold was almost the same as that of the skin nociceptors. These results show that the mucosal nociceptors are different from the skin nociceptors in the frequency distribution of their types and certain physiological properties.
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PMID:Characteristics of mucosal nociceptors in the rat oral cavity: an in vitro study. 920 7

Recent studies have indicated that nociceptors can be classified into various types according to their physiological properties. These studies have clarified that the frequency distribution of various nociceptor types is different among body sites and animal species. In the present study, we investigated the physiological properties of rat's periodontal nociceptors in an in vitro jaw-nerve preparation. Responses were recorded from functional single filaments in the inferior alveolar nerve. To determine the nociceptor type, calibrated von Frey filaments, heat, and bradykinin (BK) stimuli were used. We found five subtypes of nociceptors in the periodontal ligaments of the lower incisor: Adelta-high threshold mechanonociceptors (Adelta-HTM, n=28), Adelta-mechanoheat nociceptors (Adelta-MH, n=6), Adelta-polymodal nociceptors (Adelta-POLY, n=26), C-high threshold mechanonociceptors (C-HTM, n=3) and C-polymodal nociceptors (C-POLY, n=4). Most nociceptors were Adelta-innervated, while only a small number of C-innervated nociceptors were found. The present results suggest that periodontal nociceptors transmit mainly fast pain, and may thus play a role in rapid detection of injure-related stimuli during mastication.
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PMID:Characteristics of nociceptors in the periodontium--an in vitro study in rats. 1470 49