대한체질인류학회지제 26 권제 1 호 Korean J Phys Anthropol Vol. 26, No. 1 (2013) pp. 33~40 http://dx.doi.org/10.11637/kjpa.2013.26.1.33 Original Article 흰쥐어금니치수에서 Peripherin 발현축삭의분포 김태헌, 배용철, 양은선 경북대학교치의학전문대학원구강해부학교실 (2013 년 2 월 13 일접수, 2013 년 3 월 8 일수정접수, 2013 년 3 월 13 일게재승인, Published Online 30 March 2013) 간추림 : 치아내에존재하는축삭들은대부분민말이집축삭들과일부작은말이집축삭들로구성되어있다. 이러한축삭들은각각다른통증전도에관련되어있으며, 축삭들의종류에따라다양한신경전달물질들과수용체들을함유하고있다. 그러나치수내에존재하는다양한축삭들의분포양상과종류에따른특징들에대해아직정확하게알려진바가없다. 이연구에서민말이집축삭과작은말이집축삭들의표지자인 peripherin을발현하는축삭들의치수내분포양상을알아보기위해, 흰쥐의위턱어금니치수를대상으로 peripherin항체를사용하여면역조직화학법을실시하였다. Peripherin 면역양성축삭들은대부분치수가쪽영역에분포하였으며, 일부는상아질모세포층에도분포하였다. 또한, neurofilament200을함유한 peripherin 면역양성축삭들은치수머리영역중심부 (79.3±2.8%) 와신경얼기영역 (78.6±1.9%) 에비해상아질모세포층에서공존율 (86.3±3.0%) 이유의하게높게나타냈으며 CGRP를함유한 peripherin 면역양성축삭들은치수머리영역중심부 (37.7±10.1%) 와신경얼기부분 (40.0±5.7%) 에비해상아질모세포층에서유의하게낮은공존율 (17.7±5.0%) 을나타냈다. 이상의결과들은치수내에존재하는축삭들중작은말이집축삭들은상아질모세포층영역에서통증전달에관여하며, 펩타이드성민말이집축삭들은주로치수머리부분의중심부와신경얼기영역에서통증전달에관여할것이라는것을시사한다. 찾아보기낱말 : Peripherin, 신경분포, 치수 서 론 치아는여러자극에의해극심한통증이빈발하는부위이며, 감각신경들이풍부하게분포하고있어통증연구모델로많이활용되고있다. 치수 (dental pulp) 내에존재하는축삭 (axon) 들은대부분삼차신경절 (trigeminal ganglion) 에서투사되는감각신경축삭으로구성되어있으며이들의대부분은민말이집 C 축삭 (unmyelinated C axon) 과일부작은말이집 Aδ 축삭 (small myelinated Aδ axon) 으로구성되어있으며, 소수의큰말이집 * 이논문은 2012년도정부 ( 교육과학기술부 ) 의재원으로한국연구재단의기초연구사업지원을받아수행된것임 (No. 2012 R1A1A3007549 to YES) 저자 ( 들 ) 는 의학논문출판윤리가이드라인 을준수합니다. 저자 ( 들 ) 는이연구와관련하여이해관계가없음을밝힙니다. 교신저자 : 양은선 ( 경북대학교치의학전문대학원구강해부학교실 ) 전자우편 : yes95@hanmail.net Aβ 축삭 (large myelinated Aβ axon) 도존재한다고알려져있다 [1,2]. 이러한축삭들중치수내대부분을차지하는민말이집축삭과작은말이집축삭은각기다른통증을전도한다고알려져있다. 민말이집축삭은염증등과같은치수에직접적으로가해지는자극에의해활성화되며, 둔한통증 (dull pain) 과작열감 (burning pain) 을매개하는반면, 작은말이집축삭은상아질노출에의한자극 (drilling 또는 air drying) 을통해활성화되며, 극심하고 (acute) 날카로운통증 (sharp pain) 을매개한다 [3,4]. 따라서, 어떤형태의축삭이치수의어느부분에서발현되는가를이해하는것은, 염증이나신경손상시발생하는치수과민화현상을연구하는데중요하다. Neurofilament200 (NF200) 은말이집축삭의표지자로널리사용되고있다 [5,6]. 그러나최근전자현미경학에의한연구는성쥐의치수에서 NF200 면역양성신경섬유가다수민말이집축삭에분포하며, 이는삼차신경
34 김태헌, 배용철, 양은선 절에서유래한말이집축삭이치수의가쪽 (peripheral) 부위로가지를내면서형태학적변화를수반함으로써야기된다고보고하고있다 [7]. 치수내에분포하는축삭들은많은신경전달물질들을포함하고있으며, 그중에서 CGRP는염증성동통과관련된신경전달물질로써주로펩타이드성민말이집혹은작은말이집축삭에서발현된다 [8,9]. 본연구에서는흰쥐어금니치수에서신경섬유의분포에따른신경전달에관한기능적인의미를이해하고자, 통각을전달하는신경섬유인민말이집신경섬유와작은말이집신경섬유에서발현되는 peripherin [10,11], NF200, 그리고 CGRP항체를이용하여면역형광염색을실시한후, 이들의발현양상과공존률을정량분석하였다. 재료및방법 이연구와관련하여수행한실험동물의보호및처치는경북대학교동물실험윤리위원회에서승인을받아서진행하였다. 본연구에서는몸무게 300~330 g 사이의 Sprague- Dawley계흰쥐3마리를사용하였다. 실험동물을 sodium pentobarbital (80 mg/kg, I.p.) 을사용하여깊이전신마취를시키고오름대동맥을통하여 100 ml의헤파린을함유한생리식염수로혈관내혈액을제거한후, 400 ml 의 4% paraformaldehyde (PFA, in 0.1 M Phosphate buffer, ph 7.4) 를사용하여관류고정을시행하였다. 관류고정후위턱어금니에서치과용절삭기구를사용하여치아경조직을제거한다음치수를분리하였다. 분리한치수는인산완충용액 (Phosphate buffer; PB) 에 10분간 3회세척하였으며, 동결에의한손상을최소화하기위해 30% sucrose 용액에약 16시간동안처리한후, 동결절편기를이용하여 30 μm 두께의절편을제작하고형광면역조직화학법을시행하였다. 형광면역염색과정의모든반응은실온에서그리고진탕을하면서시행하였다. 조직절편내항체의침투를용이하게하기위해 50% ethanol 에 30분간절편을침적하였으며, 0.01 M phosphate buffered saline (PBS, ph 7.4) 으로 5분간 3회세척한후 10% normal donkey serum (NDS, Jackson ImmunoReserch, West Grove, PA) 에서 30분간반응시켜비특이적반응을최소화하도록하였다. 그후peripherin 항체 (1 : 100; Goat anti-peripherin, Santa Cruz Biotechnology, CA, USA), neurofilament200 항체 (1 : 5000; Mouse anti-neurofilament200, Sigma, St. Louis, USA), CGRP 항체 (1 : 1000; Rabbit anti-cgrp, Immunostar, Hudson, WI) 를 16시간동안처리하였으며, 0.01 M PBS로치수절편을 10분간 3회세척한다음, 2% NDS로 30분간반응하였다. 이후 2차항체로서형광물질이결합된항체 (Cy3-conjugated donkey anti-goat IgG antibodies, FITC-conjugated donkey anti-mouse IgG antibodies, FITC-conjugated donkey antirabbit IgG antibodies; 1 : 200, Jackson ImmunoResearch) 를 3시간반응시킨후, 0.01 M PBS 및증류수로다시 10분간 3회씩세척한다음형광용슬라이드위에절편을올린후공초점레이저주사현미경 (LSM510META; Carl Zeiss, Gottingen, Germany) 으로관찰및분석을실시하였다. 이들현미경영상은 TIFF 확장자파일로저장하였으며, Adobe Photoshop 7.0 (Adobe System, San Jose, CA) 을이용하여명도와대비를조정하였다. 흰쥐의위턱어금니치수에서 peripherin 면역양성축삭과 CGRP 혹은 NF200 면역양성축삭간의공존율확인을위해다음과같은정량분석을실시하였다. 흰쥐 3 마리의어금니에서얻은 9개의치수절편에서치수중심부, 관상치수가쪽 (plexus of Raschkow), 상아질모세포층영역별로각 3장씩의이미지를채득한후, 사진을통해분석하였다. 이사진은치수머리부분의중심부와가쪽에서공초점레이저주사현미경을이용하여 40 /1.2 NA objectives (1 μm of optical slice thickness) 로촬영하였다. 촬영된이미지에서 peripherin 면역양성축삭과 CGRP를함유한 peripherin 면역양성축삭, peripherin 면역양성축삭과 NF200을함유한 peripherin 면역양성축삭의수를헤아림으로써공존율을측정하였다. 그리고축삭들간의정확한공존을확인하기위해 z-series images를이용하여다시한번확인하였다. 치수내영역구분을위해이미지상에서밝기와대비값을조정하여상아질모세포체를경계로구분하였다. 또한, 망상으로분포하는치수내축삭들의중복산정오류를최대한으로줄이기위해연속으로자른절편에서 4장간격으로절편을획득하여실험을실시하였다. 치수영역별측정결과에대한통계학적분석과비교는 one-way ANOVA (Scheffe 검정 ) 를사용하여신뢰수준 95% 에서실시하였다. 결과 흰쥐위턱어금니치수에서 peripherin에대한면역반응은치수뿌리영역에서치수머리영역에이르기까지선형태로나타났으며, 염주알 (varicosity) 모양과같은형태
치수의 Peripherin 발현 35 Fig. 1. Photomicrograph showing peripherin+ axons in the rat maxillary molar pulp. A: Peripherin+ axons run within the axon bundle of the radicular pulp where they usually do not branch. B: Peripherin+ axons branch to the peripheral region in the central portion of the coronal pulp. C: Peripherin+ axons form plexus in the peripheral pulp. D: Some peripherin+ axons (arrowheads) run into the odontoblast layer of the peripheral pulp. D is higher magnification of the rectangle in the C. Scale bars=50 μm (A, B), 25 μm (C, D). OB layer: odontoblast layer. 는관찰되지않았다. 또한치수내다른조직에서면역양성은관찰되지않았다. Peripherin 면역양성축삭은치수뿌리 (radicular pulp) 부분에서는대부분가지를거의내지않은채치수머리영역으로다발형태를이루어주행하며, 소수 peripherin 면역양성축삭은치수뿌리영역에서낱가지 (single fiber) 로존재하였다 (Fig. 1A). 이들축삭은치수의중심부에서치수가쪽 (peripheral pulp) 으로여러갈래로나뉘어주행한후 (Fig. 1B), 상아질모세포층 (odontoblast layer) 의아래쪽에서신경얼기 (plexus) 를형성하였고 (Fig. 1C), 일부는상아질모세포층사이로주행하는것을관찰하 였다 (Fig. 1D). Peripherin 면역양성축삭들 (Fig. 2A and 2D) 의대다수는 NF200 (Fig. 2B and 2E) 에대해서도면역양성반응을보였다. 치수머리부분의중심부 (core; Fig. 2C-III and 2F) 에서의공존율 (NF200면역양성/peripherin면역양성 ) 은약 79.3±2.8% (297/375) 였고, 신경얼기 (Fig. 2C- II) 에서의공존율은 78.6±1.9% (363/462) 로써중심부및신경얼기부위사이에서공존율은유의한차이를보이지않았다. 그러나상아질모세포층 (Fig. 2C-I and 2F) 에서의공존율은약 86.3±3.0% (252/292) 로앞의다른두부위에비해유의하게높았다 (P 0.05; Fig. 4).
36 김태헌, 배용철, 양은선 Fig. 2. Photomicrographs showing colocalization of peripherin+ axons with NF200 in the rat maxillary molar pulp. A~C: Immunostaining of rat molar pulp reveal almost peripherin+ axons colabeled with NF200 in pulpal horn (A: red, peripherin, B: green, NF200, C: yellow, colabeled). D~F: D, E, F are higher magnifications of the boxed areas in the A, B, C, respectively showing peripherin and NF 200 immunopositive axons in peripheral region. Peripherin+ axons are colabeled with NF200+ fibers in peripheral region. Scale bars=50 μm(a~c), 10 μm(d~f). I: odontoblast layer, II: plexus, III: core. OB layer : odontoblast layer. Peripherin을발현하는신경섬유들 (Fig. 3A and 3D) 중 CGRP를발현하는신경섬유들 (Fig. 3B and 3E) 은치수머리중심부 (Fig. 3C and 3F-III) 와신경얼기 (Fig. 3C and 3F-II) 에서는각각약 37.7±10.1% (143/381), 40.0 ±5.7% (190/474) 였으나, 상아질모세포층 (Fig. 3C and 3F-I) 에서는약 17.7±5.0% (54/305) 로다른두부위에비해유의하게낮은공존율을보였다 (P 0.05; Fig. 4). 고찰 이연구를통하여치수내에서발현하는 peripherin 면역양성축삭들은 1) 대부분신경얼기와상아질모세포층에서밀집되어분포하고, 2) peripherin 면역양성신경섬유들의대부분이 NF200에대하여면역양성반응을나타내며, 특히상아질모세포층에서보다높은공존율 을나타낸반면, 3) CGRP와의공존율은상아질모세포층에서유의하게낮아진다고밝혔다. 이전보고에의하면말초신경계에서 peripherin 면역양성반응은작거나중간크기의뒤뿌리신경절 (dorsal root ganglion, DRG) 신경원의세포체에서대부분나타나고 [10], 이러한형태학적특징을나타내는 DRG의신경원은일반적으로전기생리학적으로민말이집 C 신경섬유혹은작은말이집 Aδ 신경섬유를가지는통증전도감각신경세포체가대다수인것으로알려져있다 [12]. 또한 Ho와 O Leary [13] 에의하면 DRG에서단세포배양을하여 RT-PCR을통한peripherin을발현하는신경세포체의크기를분석한결과큰신경세포체 ( 30 μm) 에비해작은신경세포체 ( 25 μm) 에서 1.5배더많이발현하였다고보고하였으며, 이를통해 peripherin은작거나중간크기의신경세포체에서발현함을유추할수있다. 민말이집축삭과작은말이집축삭은통각을전달
치수의 Peripherin 발현 37 Fig. 3. Photomicrographs showing colocalization of peripherin+ fibers with CGRP in the rat maxillary molar pulp. A~C: Some peripherin+ axons show colocalization with CGRP in the pulpal horn (A: red, peripherin, B: green, CGRP, C: yellow, colabeled). D~F: D, E, F are higher magnifications of the boxed areas in the A, B, C, respectively showing colocalization of peripherin+ axon with CGRP in the peripheral region. Scale bars=50 μm(a~c), 10 μm(d~f). I: odontoblast layer, II: plexus, III: core. Colocalization (%) 100 80 60 40 20 0 * NF200+/PER+ Central Plexus Odontoblast layer Fig. 4. Histogram showing colocalization (%) of peripherin+ axon with neurofilament200 (NF200) or CGRP in rat maxillary molar. Proportion of peripherin+ axons showing colocalization with NF 200 is significantly higher in the odontoblast layer than in the central and plexus regions. Proportion of peripherin+ axons showing colocalization with CGRP is significantly lower in the odontoblast layer region than in the central and plexus regions (One-way ANOVA, P 0.05). * CGRP+/PER+ 하는데관여하는신경축삭들이다. 민말이집축삭은둔하게느끼는통증 (dull), 작열감 (burning pain) 을매개하며치수자극에의해활성화되는축삭이며, 작은말이집축삭은날카로운통증 (sharp pain), 급성통증을매개하는축삭이다 [3,4]. 따라서 peripherin 면역양성축삭들은민말이집축삭과작은말이집축삭이므로이러한축삭들에의한통증을전달할것으로추측된다. 본연구에서 peripherin 면역양성축삭들은치수머리영역의신경얼기 (plexus of Raschkow) 와상아질모세포층에주로분포되어있었다. 이러한분포양상은 Veerayutthwilai 등 [14] 의보고와유사하며, 이는이들대다수가주로치수가쪽의신경얼기부위, 상아질모세포층부위에서통증전도와관련한기능을주로수행할것이라는것을나타낸다. Peripherin은주로작거나중간크기의신경세포체와그들의민말이집축삭과작은말이집축삭에서발현하는반면, NF200은중간크기와큰크기의신경세포체
38 김태헌, 배용철, 양은선 와이들로부터유래하는말이집축삭에서발현한다 [10, 15]. 또한, Goldstein 등 [10] 은 peripherin과 neurofilament 모두를발현하는 DRG 신경세포체는전체신경세포체의약 5.6% 이며, 이들대부분은작은말이집축삭을가진중간크기의신경세포체라고보고하였다. 이러한보고와 peripherin 면역양성축삭들은대다수 NF200을발현한다는본연구의결과를고려하면, 삼차신경절에서도 peripherin과 NF200를발현하는중간크기의신경세포체가소수존재할가능성이있으며, 이들로부터유래하는작은말이집축삭들이치수로투사할것이라는점을시사한다. 이는 Paik 등 [7] 이흰쥐어금니치수로투사하는삼차신경절인접부의축삭은대다수작은말이집축삭이라는보고와일치한다. 또한이연구에서 peripherin과 NF200을공히발현하는축삭들이치수뿌리영역과신경얼기영역에비해상아질모세포층부위에서훨씬더많이분포하였다는결과는치수로투사된작은말이집축삭들이상아질모세포와의상호작용을통한 odontogenic pain 혹은 hydrodynamic theory와같은상아세관내에서의액체이동에의한통증전달에크게기여할것임을시사한다 [16,17]. CGRP는주로염증성동통전달에관련된신경전달물질로서, 펩타이드성민말이집혹은작은말이집축삭표지자로많이사용되며 [8,9], 혈관확장, 대식세포와백혈구조절등의면역작용에관여한다고알려져있다 [18,19]. 또한치수에염증이발생하였을때 CGRP 면역양성축삭들은염증부위에서급격히그수가증가하는 sprouting 현상을보임으로써치수염에따른염증성통각과민에깊이관여하는물질로알려져있으며 [20-22], 이러한 sprouting이이차상아질형성과재생과정에관여할것이라는주장도제시된바있다 [22,23]. 본연구에서 peripherin 면역양성축삭들중 CGRP를함유한축삭들이다수 ( 약 40%) 존재하였으며, 상아질모세포층아래신경얼기영역에서 CGRP를함유한 peripherin 면역양성축삭이많고상아질모세포층영역에서는적게관찰되었다. 이는치수내에분포하는민말이집혹은작은말이집축삭들중 40% 는 CGRP를함유한펩타이드성축삭이며, 이들은주로신경얼기그리고일부상아질모세포층영역에서통증전도및염증성지각과민에관여할것으로추측된다. 이러한분포양상은 Rodd와 Boissonade [24] 이 CGRP 면역양성축삭들은신경얼기영역에많이분포한다는보고와일치하며 Byers와 Närhi [25] 이 CGRP를함유한축삭들이상아질모세포층으로투사되며일부상아세관으로투사된다는보고와도일치한다. 따라서 CGRP를함유한펩타이드 성민말이집혹은작은말이집축삭들은신경얼기영역과상아질모세포층혹은상아세관내에일부분포하면서염증성동통전달뿐아니라염증에의한조직손상시재생작용에도관여할것으로추측된다. 또한 peripherin 면역양성축삭중 CGRP를발현하지않는축삭이 60% 정도존재하며이러한축삭들은펩타이드를함유하지않은비펩타이드성축삭이라고추측된다. Byers 등 [26] 에의하면치수내에존재하는작은말이집과민말이집축삭에는많은신경화학물질들이존재하며비펩타이드성인 Isolectin B4 (IB4) 가발현된다고보고하였다. 또한 IB4를발현하는축삭은강한전압에의한자극이나유해한조직손상에의해활성화될것이라추측하였다. 그리고 Alavi 등 [27] 은 ATP수용체인 P2X3 가치수에분포함을보고하였고이러한 P2X3를발현하는축삭은 NF200을발현하는축삭과완전히일치하며 IB4를발현하는축삭과약 40% 정도의공존율을보인다고했다. 따라서, 이러한결과는치수내에펩타이드성민말이집축삭뿐만아니라다른여러종류의축삭들이존재하며이러한다양한축삭들에의해치아에발생하는통증이전달될것으로추측된다. 치아통증은여러가지원인들에의해서발생하며이러한통증은여러전달경로를통해서전달된다. 본실험에서살펴본치수내의신경축삭들은통증전달에관여하는중요한요소이다. 따라서치수내에존재하는민말이집, 말이집축삭에대한정확한기능적역할이밝혀진다면치아통증연구에좀더도움이될것이라사료된다. 참고문헌 1. Bueltmann KW, Karlsson UL, Edie J. Quantitative ultrastructure of intradental nerve fibres in marmosets. Arch Oral Biol. 1972; 17:645-60. 2. Naftel JP, Bernanke JM, Qian XB. Quantitative study of the apical nerve fibers of adult and juvenile rat molars. Anat Rec. 1994; 238:507-16. 3. Narhi MV. Dentin sensitivity. J Biol Buccale. 1985; 13:75-96. 4. Markowitz K, Kim S. Hypersensitive teeth. Experimental studies of dentinal desensitizing agents. Dent Clin North Am. 1990; 34:491-501. 5. Lawson SN, Waddell PJ. Soma neurofilament immunoreactivity is related to cell size and fibre conduction velocity in rat primary sensory neurons. J Physiol. 1991; 435:41-63. 6. Sann H, McCarthy PW, Jancso G, Pierau FK. RT97: a mar-
치수의 Peripherin 발현 39 ker for capsaicin-insensitive sensory endings in the rat skin. Cell Tissue Res. 1995; 282:155-61. 7. Paik SK, Park KP, Lee SK, Ma SK, Cho YS, Kim YK, et al. Light and electron microscopic analysis of the somata and parent axons innervating the rat upper molar and lower incisor pulp. Neuroscience. 2009; 162:1279-86. 8. Awawdeh L, Lundy FT, Shaw C, Lamey PJ, Linden GJ, Kennedy JG. Quantitative analysis of substance P, neurokinin A and calcitonin gene-related peptide in pulp tissue from painful and healthy human teeth. Int Endod J. 2002; 35:30-6. 9. Hill EL, Elde R. Calcitonin gene-related peptide-immunoreactive nerve fibers in mandibular periosteum of rat: evidence for primary afferent origin. Neurosci Lett. 1988; 85: 172-8. 10. Goldstein ME, House SB, Gainer H. NF-L and peripherin immunoreactivities define distinct classes of rat sensory ganglion cells. J Neurosci Res. 1991; 30:92-104. 11. Garry EM, Delaney A, Anderson HA, Sirinathsinghji EC, Clapp RH, Martin WJ, et al. Varicella zoster virus induces neuropathic changes in rat dorsal root ganglia and behavioral reflex sensitisation that is attenuated by gabapentin or sodium channel blocking drugs. Pain. 2005; 118:97-111. 12. Harper AA, Lawson SN. Conduction velocity is related to morphological cell type in rat dorsal root ganglion neurones. J Physiol. 1985; 359:31-46. 13. Ho C, O Leary ME. Single-cell analysis of sodium channel expression in dorsal root ganglion neurons. Mol Cell Neurosci. 2011; 46:159-66. 14. Veerayutthwilai O, Luis NA, Crumpton RM, MacDonald GH, Byers MR. Peripherin- and CGRP-immunoreactive nerve fibers in rat molars have different locations and developmental timing. Arch Oral Biol. 2006; 51:748-60. 15. Lawson SN, Perry MJ, Prabhakar E, McCarthy PW. Primary sensory neurones: neurofilament, neuropeptides, and conduction velocity. Brain Res Bull. 1993; 30:239-43. 16. Hildebrand C, Fried K, Tuisku F, Johansson CS. Teeth and tooth nerves. Prog Neurobiol. 1995; 45:165-222. 17. Brannstrom M. Etiology of dentin hypersensitivity. Proc Finn Dent Soc. 1992; 88 Suppl 1:7-13. 18. Payan DG, McGillis JP, Renold FK, Mitsuhashi M, Goetzl EJ. Neuropeptide modulation of leukocyte function. Ann N Y Acad Sci. 1987; 496:182-91. 19. Peck R. Neuropeptides modulating macrophage function. Ann N Y Acad Sci. 1987; 496:264-70. 20. Kimberly CL, Byers MR. Inflammation of rat molar pulp and periodontium causes increased calcitonin gene-related peptide and axonal sprouting. Anat Rec. 1988; 222:289-300. 21. Khayat BG, Byers MR, Taylor PE, Mecifi K, Kimberly CL. Responses of nerve fibers to pulpal inflammation and periapical lesions in rat molars demonstrated by calcitonin generelated peptide immunocytochemistry. J Endod. 1988; 14: 577-87. 22. Taylor PE, Byers MR, Redd PE. Sprouting of CGRP nerve fibers in response to dentin injury in rat molars. Brain Res. 1988; 461:371-6. 23. Byers MR. Segregation of NGF receptor in sensory receptors, nerves and local cells of teeth and periodontium demonstrated by EM immunocytochemistry. J Neurocytol. 1990; 19:765-75. 24. Rodd HD, Boissonade FM. Comparative immunohistochemical analysis of the peptidergic innervation of human primary and permanent tooth pulp. Arch Oral Biol. 2002; 47: 375-85. 25. Byers MR, Narhi MV. Dental injury models: experimental tools for understanding neuroinflammatory interactions and polymodal nociceptor functions. Crit Rev Oral Biol Med. 1999; 10:4-39. 26. Byers MR, Suzuki H, Maeda T. Dental neuroplasticity, neuro-pulpal interactions, and nerve regeneration. Microsc Res Tech. 2003; 60:503-15. 27. Alavi AM, Dubyak GR, Burnstock G. Immunohistochemical evidence for ATP receptors in human dental pulp. J Dent Res. 2001; 80:476-83.
40 김태헌, 배용철, 양은선 Distribution of Peripherin Immunoreactive Axons in Rat Molar Pulp Tae-Heon Kim, Yong-Chul Bae, Eun-Sun Yang Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University Abstract : Dental pulp is innervated mostly by unmyelinated axons and small myelinated axons. These axons are implicated pain transmission and contain various neurotransmitters and receptors. However, little information, so far, is available on the distribution pattern and characterization of axons involved in the dental pain. In this study, to enhance understanding of dental pain processing, we observed distribution of axons expressing peripherin, an unmyelinated and small myelinated axonal marker, the in rat maxillary molar pulp. Peripherin-immunopositive (+) axons are mostly distributed in the peripheral pulp, and a few peripherin+ axons ascend into the odontoblast layer. Peripherin+ axons expressing NF200 are more frequently observed in the odontoblast layer (86.3±3.0%) than in the pulpal core region (79.3±2.8%) and nerve plexus region (78.6± 1.9%). In contrast, peripherin+ axons expressing CGRP are less frequently observed in the odontoblast layer (17.7±5.0%) than in the pulpal core (37.7±10.1%) and nerve plexus regions (40.0±5.7%). These findings indicate that small myelinated axons are implicated in the transmission of dental pain arising from the odontoblast layer while peptidergic unmyelinated axons are implicated in the transmission of dental pain arising from central core and nerve plexus regions of the dental pulp. Keywords : Peripherin, Innervation, Dental pulp Correspondence to : Eun-Sun Yang (Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea) E-mail : yes95@hanmail.net