electroacupuncture stimulation at cv12 inhibits gastric ......electroacupuncture stimulation at cv12...

Hindawi Publishing CorporationEvidence-Based Complementary and Alternative MedicineVolume 2013 Article ID 294789 6 pageshttpdxdoiorg1011552013294789

Research ArticleElectroacupuncture Stimulation at CV12 InhibitsGastric Motility via TRPV1 Receptor

Zhi Yu1 Xin Cao12 Youbing Xia13 Binbin Ren1 Hong Feng1 Yali Wang1

Jingfeng Jiang1 and Bin Xu1

1 Key Laboratory of Integrated Acupuncture and Drugs Constructed by the Ministry of Education and Jiangsu ProvinceNanjing University of Chinese Medicine Nanjing 210029 China

2 Toho University Tokyo 143-8540 Japan3Nanjing Medical University Nanjing 210029 China

Correspondence should be addressed to Bin Xu xuuuuxsinacom

Received 25 February 2013 Accepted 9 August 2013

Academic Editor Jian Kong

Copyright copy 2013 Zhi Yu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Gastric dysmotility is one of the major pathophysiological factors in functional gastrointestinal disorders Acupuncture as one ofthe alternative approaches is efficacious in the treatment of gastrointestinal motility disorders however themechanism underlyingits action is unclear In the present study we used both capsazepine a TRPV1 antagonist and TRPV1 knockout mice Animalswere divided into wild-type group (WT) capsazepine injection group (CZP 05mgkg ip) and TRPV1 knockout mice group(TRPV1minusminus) Each of these three groups was divided into three subgroups which were subjected to EA stimulation at acupointZhongwan (CV12) at a different intensity (1 2 or 4mA)We demonstrated that electroacupuncture at Zhongwan (CV12) markedlyinhibited gastricmotility at 2 and 4mA in an intensity-dependentmanner inwild-typemiceThe inhibitory effect was also observedin capsazepine-injected and TRPV1minusminus mice but was no longer intensity dependent indicating that TRPV1 is partially involved inthe electroacupuncture-mediated modulation of gastric motility

1 Introduction

Gastric motility is one of the most critical physiological func-tions of the human body Coordinated gastric motility is nec-essary for the digestion and absorption of dietary nutrientsImpairment of gastric motility results in delayed gastric emp-tying and symptoms such as nausea vomiting and abdom-inal pain and discomfort [1] Recent studies have shown thatgastric dysmotility is one of the major pathophysiologicalfactors in functional gastrointestinal disorders which has apublic health cost of over 30 billion dollars annually [2 3]including functional dyspepsia [4] and gastroesophagealreflux disease [5]

Acupuncture has been practiced for thousands of years inEastern countries and has become very popular worldwide asa complementary and alternative approach Numerous stud-ies on both humans and animals support the efficacy ofacupuncture for treating gastrointestinal symptoms andordiseases of gastrointestinal secretion [6 7] sensation [8]

and myoelectrical activity [9] Acupuncture of the abdomenhas been used for treating abdominal pain suggestingthat acupuncture of this site may inhibit gastric motilityandor reduce gastrospasm [10] Recently many studies haveexplored the efficacy of electroacupuncture (EA) for thetreatment of gastrointestinal motility disorders and con-cluded that EA can alter gastrointestinalmotility and improvegastrointestinalmotility disorders [11]While this therapeuticeffect of EA has been proved little is known about theunderlying mechanism(s)

The transient receptor potential vanilloid-1 (TRPV1 tran-sient receptor potential (TRP) cation channel subfamily Vmember 1) is a member of the superfamily of TRP cationchannels [12] TRPV1 plays an important role in the modu-lation of EA efficacy owing to its function in heat andmechanical sensations [13ndash15] However research on TRPV1and EA has mainly been confined to the treatment of painsuch as cancer-related pain or hyperalgesia Few studieshave reported the relationship between EA and TRPV1 in

2 Evidence-Based Complementary and Alternative Medicine

Start EndEA

2min

(a)

Start EndEAVehicle ip CZP ip

2min5min5min

(b)

Figure 1 Experimental procedure (a) Time scale of stimulation in the wild-type and TRPV1minusminus groups (b) Time scale of stimulations in thecapsazepine (CZP) injection group

the regulation of gastrointestinal motility We previouslyreported themodulatory effects of EA on gastricmotility [16]Given the emerging role of TRPV1 receptors in mediatingsensory and visceral functions the aim of the present studywas to further elucidate the mechanism of EA-mediatedgastric motility modulation and to confirm whether TRPV1was involved in this mechanism

2 Materials and Methods

21 Animals TRPV1minusminus mice (119899 = 30 male 22ndash28 gB6129X1-TRPV1tm1JulNJU J003770) and their wild-typecounterparts (WT 119899 = 60 male 22ndash28 g) were purchasedfrom Model Animal Research Center of Nanjing University(Nanjing China) Food and water were made available adlibitum and the animals were housed under controlled envi-ronmental conditions (22∘C 40ndash60 relative humidity12-h alternate lightdark cycles) All experimental manip-ulations were undertaken in accordance with the NationalInstitutes of Health Guide for the Care and Use of LaboratoryAnimals and with the approval of the Scientific InvestigationBoard of the Nanjing University of Traditional ChineseMedicine Nanjing China

22 Experimental Groups Capsazepine injections were usedin 30 of the 60WTmice (CZP group) but not in the remain-ing 30WTmice (WT group) or the 30 TRPV1 knockoutmice(TRPV1minusminus group) Each of these three groups was dividedinto three subgroups of 10mice each and the three subgroupsof each group were subjected to EA stimulation at a differentintensity (1 2 or 4mA)

23 Experimental Procedure The animals were fasted over-nightwith free access towater and anesthetizedwith urethane(12 gkg ip U2500 Sigma USA) The trachea was cannu-lated to keep the respiratory tract patent and gastric motilitywas recorded using a previously described method [17] Asmall incision was made in the duodenum about 1-2 cmfrom the pylorus A small balloon made of flexible condomrubber was inserted into the pyloric area via incision Thepressure in the balloon was measured with a transducer(YP200 Chengdu Instrument Factory Chengdu China)and recorded with a physiological signal-acquisition system(RM6240 Chengdu Instrument Factory) for further analysisDuring the experiment the temperature of the animal wasmaintained at 37∘C plusmn 05∘C using an electric heating board

The experimental procedure in the WT and TRPV1minusminusgroups is shown in Figure 1(a) The time scale of eachstimulation in the capsazepine injection group is shown in

Figure 1(b) Capsazepine (05mgkg ip C191 Sigma USA)was dissolved in a vehicle (1 dimethyl sulfoxide D8418Sigma USA)

24 EA Stimulation A pair of needle electrodes (diameter03mm) were inserted approximately 5mm deep into theZhongwan point (CV12) which is located at the center of theabdomen in the midline of the body [17] The EA intensitywas set as 1 2 or 4mA with alternating frequencies of 2Hzand 15Hz for 2min

25 Statistical Analysis Data were analyzed using SPSS 170software (SPSS Chicago USA) Differences before and aftertreatment were compared using a paired-sample 119905-test andthose between two groups were compared using an inde-pendent-sample 119905-test Comparison among groups was per-formed using analysis of variance 119875 lt 005 was consideredstatistically significant All data were expressed as mean plusmn SE

3 Results

31 Gastric Motility In the resting condition (prior to EA)rhythmic gastric contractions at a frequency of 3ndash6min wereobserved in the TRPV1minusminus and WT mice and the contractileamplitude of the rhythmic waves was approximately 005ndash03 kPa when balloon pressure was maintained at about 04ndash06 kPa by filling the balloon with 01ndash02mL warm waterInjection of 05mgkg capsazepine ip caused no change ingastric movement or amplitude

32 Gastric Response to Different Intensities of EA Stimulationat CV12 InWTmice EA stimulation at CV12 at an intensityof 1mA (119899 = 10) produced no significant effect on gastricmotility (Figure 2(a)) In contrast EA stimulation at 2mAslightly inhibited gastric motility while stimulation at 4mAstrongly inhibited it Thus the inhibition of gastric motilityby EA stimulation was intensity dependent

33 TRPV1 Is Involved in Gastric Motility Modulation byEA Stimulation To determine the mechanism underlyingthe inhibitory effect of EA stimulation at CV12 we usedcapsazepine a specific antagonist of TRPV1 In theWTmicesignificant inhibition of gastric motility was obtained afterEA stimulation at 2 and 4mA but not at 1mA moreoverthis inhibitory effect was intensity dependent being greater at4mA than at 2mA (Figure 4(e)) After capsazepine injectionEA stimulation at 1mA (119899 = 10) produced no significantinhibition while that at 2mA produced mild inhibition(Figure 3(a)) however the effect of EA stimulation at 4mA

Evidence-Based Complementary and Alternative Medicine 3

0

01

02

03

04

05

06

07

08

BaselineEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA

lowastlowast lowastlowast

(a)

(kPa

)

0

1

EA 1mA 120 s

(b)

(kPa

)

0

1

EA 2mA 120 s

(c)

(kPa

)

0

1

EA 4mA 120 s

(d)

Figure 2 Gastric response to electroacupuncture (EA) stimulation at CV12 in wild-type mice (a) Significant inhibition of gastric motilitywas induced by EA stimulation at intensities 2mA (119899 = 10) and 4mA (119899 = 10) lowastlowast Versus baseline 119875 lt 0001 (b)ndash(d) Representativeexamples of EA stimulation at CV12 with different intensities

0

01

02

03

04

05

06

07

08

BaselineVehicle

CZPEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA


(a)

0

1

(kPa

)

Vehicle CZP EA 1mA 120 s

(b)

0

1


(kPa

)

(c)

0Vehicle CZP

1

EA 4mA 120 s

(kPa

)

(d)

Figure 3 Gastric responses to electroacupuncture (EA) stimulation at CV12 after capsazepine (CZP) injection (a) Significant inhibition ofgastric motility was induced by EA at intensities 2mA (119899 = 10) and 4mA (119899 = 10) lowastlowast Versus CZP 119875 lt 0001 (b)ndash(d) Representativeexamples of EA stimulation at CV12 with different intensities


00102030405060708

Gas

tric

pre

ssur

e (kP

a)

Baseline EA

1mA 2mA 4mA


(a)

0

1

(kPa

)

EA 1 mA 120 s

(b)

(kPa

)

0

1

EA 2 mA 120 s

(c)(k

Pa)

0

1

EA 4 mA 120 s

(d)

WTCZP

Gas

tric

pre

ssur

e (

)

1mA 2mA 4mA

ΔΔΔΔ

ΔΔ

minus2000

minus1500

minus1000

minus500

000

TRPV1minusminus

(e)

Figure 4 Gastric responses to electroacupuncture (EA) stimulation at CV12 in TRPV1minusminus mice (a) Significant inhibition of gastric motilitywas induced by EA at intensities 2mA (119899 = 10) and 4mA (119899 = 10) lowastlowast Versus baseline 119875 lt 0001 (b)ndash(d) Representative examples ofEA stimulation at CV12 with different intensities (e) Percentage inhibition of gastric motility after EA stimulation at CV12 with differentintensities in all three experimental groups Versus WT 119875 lt 005 Versus WT 119875 lt 001 ΔΔ Versus 1mA 119875 lt 0001 995333 Versus 2mA119875 lt 005

was partially blocked (Figure 4(e)) Thus the intensity-dependent characteristic of EA stimulation disappeared afterTRPV1 channel blockage Similar results were obtained in theTRPV1minusminus mice (Figures 4(a)ndash4(e)) suggesting an importantrole of TRPV1 in EA-mediatedmodulation of gastricmotility

4 Discussion

The reported ameliorating effect of EA on gastric dysrhyth-mia has been consistent and reproducible suggesting a robustrole of EA in the treatment of gastric motility disorders [11]The primary mechanism underlying the clinical effects ofacupuncture appears to be the activation of afferent nerve

fibers that innervate the skin and muscles [18] In this studywe determined whether TRPV1 was involved in the EA-mediated regulation of gastric motility after stimulation ofCV12 with different intensities For this purpose we usedboth capsazepine which is a TRPV1 antagonist and TRPV1knockout mice Acupuncture stimulation of various segmen-tal areas of the body has been shown to alter gastric motilityin anesthetized animals [19 20] this alteration has been facil-itative or inhibitory depending on which acupoints arestimulated Consistent with these reports our data showedthat EA at CV12 significantly inhibited gastric motility butonly at intensities 2 and 4mAMoreover this inhibitory effectwas intensity dependent (Figure 4) which was in accordancewith previous reports [20] Somatic afferent nerve fibers are


composed ofA-120572 A-120573 A-120575 andC-fibersThemean thresholdof the action potentials of A-120575 fibers is approximately 2mA[20] while that of unmyelinated fibers is approximately3mA [21] Consistent with this [20] EA stimulation couldmodulate gastric motility only at an intensity greater than thethreshold for the activation of A-120575 andor C-fibers In otherwords the inhibitory effect of EA at 2mA was mediated byA-120575 fibers while the effect of EA at 4mA was mediated byunmyelinated fibers

TRPV1 mediates the transductions of intra- and extra-cellular signals and modulates organ functions by activatinga variety of endogenous and exogenous stimuli such asmechanical stimuli noxious heat proteins and capsaicin[22] The presence of a class of visceral and somatic afferentsof dorsal root origin and their functional significance inpain sensation have been well documented [23] RecentlyTRPV1 was found to be expressed at acupuncture pointsindicating that it contributed to the effects of EA stimulation[24] The above findings suggest the importance of TRPV1in EA stimulation To confirm whether TRPV1 was involvedin the regulation of gastric motility after CV12 stimulationwe assessed the effects of EA at CV12 on gastric motilityin TRPV1-null animals After TRPV1 blockage or knockoutEA at CV12 continued to inhibit gastric motility althoughinterestingly the intensity-dependent nature of EA-mediatedinhibition disappeared especially at intensities 2 and 4mACaterina et al [25] reported that in VR1-null mice none ofthe C-fibers examined were activated by capsaicin a specificTRPV1 agonist whereas 11 of 22 wild-type afferent nervesresponded vigorously to this stimulus Among myelinatednociceptors only one of 13 wild-type fibers and none of thenine fibers from VR1minusminus mice responded to capsaicin Theseresults indicated that TRPV1 wasmainly coexpressed with C-fibers rather than with myelinated nociceptors [25] Consis-tent with this Koerber et al [26] reported that TRPV1 wasspecifically localized in a subpopulation of C-fiber nocicep-tors that responded to heat (CH-fibers) but not tomechanicalor cold stimuli The majority of C-fibers innervating the skinare C-polymodal afferents that respond to both mechanicaland thermal stimuliThe coexpression of TRPV1 andC-fiberscombined with the identical thresholds for the elicitationof nerve action potentials and EA responses indicate thatTRPV1 is involved in the intensity-dependent regulation ofgastric motility by EA stimulation at CV12

Conflict of Interests

The authors declare they have no conflict of interests

Acknowledgments

The authors thank Professor X H Jing (Institute of Acupunc-ture and Moxibustion China Academy of Chinese MedicalSciences) for advise and Y Wang (Nanjing University ofChinese Medicine) for the assistance during experimentThis work was supported by grants from the National KeyBasic Research Program (973 Program no 2011CB505206)the National Natural Science Foundation of China (nos81202744 and 81373749) theNatural Science Research Project

of Higher Education of Jiangsu Province (no 11KJB360008)and Jiangsu Provincial Qinglan Project Sci-tech InnovationTeam

References

[1] S Zhao H Sha Z Y Li andC S Ren ldquoElectrical bioimpedancegastricmotilitymeasurement based on an electrical-mechanicalcomposite mechanismrdquoWorld Journal of Gastroenterology vol18 no 25 pp 3282ndash3287 2012

[2] N J Talley ldquoFunctional gastrointestinal disorders as a publichealth problemrdquo Neurogastroenterology and Motility vol 20 1pp 121ndash129 2008

[3] B Cash S Sullivan and V Barghout ldquoTotal costs of IBSemployer andmanaged care perspectiverdquoTheAmerican Journalof Managed Care vol 11 no 1 pp S7ndash16 2005

[4] Y Matsumoto M Ito D Kamino S Tanaka K Haruma andK Chayama ldquoRelation between histologic gastritis and gastricmotility in Japanese patients with functional dyspepsia evalua-tion by transabdominal ultrasonographyrdquo Journal of Gastroen-terology vol 43 no 5 pp 332ndash337 2008

[5] M Nahata S Muto N Oridate et al ldquoImpaired ghrelin signal-ing is associated with gastrointestinal dysmotility in rats withgastroesophageal reflux diseaserdquoAmerican Journal of PhysiologyGastrointestinal and Liver Physiology vol 303 no 1 pp G42ndashG53 2012

[6] H S Hwang K-J Han Y H Ryu et al ldquoProtective effects ofelectroacupuncture on acetylsalicylic acid-induced acute gas-tritis in ratsrdquo World Journal of Gastroenterology vol 15 no 8pp 973ndash977 2009

[7] E Noguchi ldquoAcupuncture regulates gut motility and secretionvia nerve reflexesrdquoAutonomic Neuroscience vol 156 no 1-2 pp15ndash18 2010

[8] X Y Tian Z X Bian X G Hu X J Zhang L Liu and HZhang ldquoElectro-acupuncture attenuates stress-induced defeca-tion in rats with chronic visceral hypersensitivity via serotoner-gic pathwayrdquo Brain Research vol 1088 no 1 pp 101ndash108 2006

[9] C M Witt K Meissner D Pach et al ldquoStimulation of gastricslow waves with manual acupuncture at acupuncture pointsST36 and PC6mdasha randomized single blind controlled trialrdquoNeurogastroenterology and Motility vol 24 no 5 pp 438ndash4452012

[10] Y-Q Li B Zhu P-J Rong H Ben and Y-H Li ldquoEffective reg-ularity in modulation on gastric motility induced by differentacupoint stimulationrdquo World Journal of Gastroenterology vol12 no 47 pp 7642ndash7648 2006

[11] J Yin and J D Z Chen ldquoGastrointestinal motility disorders andacupuncturerdquo Autonomic Neuroscience vol 157 no 1-2 pp 31ndash37 2010

[12] R Rahmati ldquoThe transient receptor potential vanilloid receptor1 TRPV1 (VR1) inhibits peristalsis in the mouse jejunumrdquoArchives of Iranian Medicine vol 15 no 7 pp 433ndash438 2012

[13] Z Zhang CWang G Gu et al ldquoThe effects of electroacupunc-ture at the ST36 (Zusanli) acupoint on cancer pain and transientreceptor potential vanilloid subfamily 1 expression in walker256 tumor-bearing ratsrdquo Anesthesia and Analgesia vol 114 no4 pp 879ndash885 2012

[14] S J Wang H Y Yang and G S Xu ldquoAcupuncture alleviatescolorectal hypersensitivity and correlates with the regulatorymechanism of trpV1 and p-ERKrdquo Evidence-Based Complemen-tary and Alternative Medicine vol 2012 Article ID 483123 10pages 2012


[15] L Manni F Florenzano and L Aloe ldquoElectroacupuncturecounteracts the development of thermal hyperalgesia and thealteration of nerve growth factor and sensory neuromodulatorsinduced by streptozotocin in adult ratsrdquo Diabetologia vol 54no 7 pp 1900ndash1908 2011

[16] Z Yu Y B XiaM X Lu J LinW J Yu and B Xu ldquoInfluence ofelectroacupuncture stimulation of tianshu (ST25) quchi (LI11)and shangjuxu (ST37) and their pairs on gastric motility in theratrdquo Acupuncture Research vol 38 no 1 pp 40ndash47 2013

[17] X Y Wang H Shi H Y Shang et al ldquoAre primo vessels (PVs)on the surface of gastrointestine involved in regulation of gastricmotility induced by stimulating acupoints ST36 or CV12rdquoEvidence-Based Complementary and Alternative Medicine vol2012 Article ID 787683 8 pages 2012

[18] F Kagitani S Uchida and H Hotta ldquoAfferent nerve fibers andacupuncturerdquoAutonomic Neuroscience vol 157 no 1-2 pp 2ndash82010

[19] A Sato Y Sato A Suzuki and S Uchida ldquoNeural mechanismsof the reflex inhibition and excitation of gastric motility elicitedby acupuncture-like stimulation in anesthetized ratsrdquo Neuro-science Research vol 18 no 1 pp 53ndash62 1993

[20] Y-Q Li B Zhu P-J Rong H Ben and Y-H Li ldquoNeuralmechanism of acupuncture-modulated gastric motilityrdquoWorldJournal of Gastroenterology vol 13 no 5 pp 709ndash716 2007

[21] H Ohsawa S Yamaguchi H Ishimaru M Shimura and YSato ldquoNeural mechanism of pupillary dilation elicited byelectro-acupuncture stimulation in anesthetized ratsrdquo Journalof the Autonomic Nervous System vol 64 no 2-3 pp 101ndash1061997

[22] D-L Liu W-T Wang J-L Xing and S-J Hu ldquoResearchprogress in transient receptor potential vanilloid 1 of sensorynervous systemrdquo Neuroscience Bulletin vol 25 no 4 pp 221ndash227 2009

[23] L M Patterson H Zheng S M Ward and H-R BerthoudldquoVanilloid receptor (VR1) expression in vagal afferent neuronsinnervating the gastrointestinal tractrdquo Cell and Tissue Researchvol 311 no 3 pp 277ndash287 2003

[24] T S Abraham M-L Chen and S-X Ma ldquoTRPV1 expressionin acupuncture points response to electroacupuncture stimula-tionrdquo Journal of Chemical Neuroanatomy vol 41 no 3 pp 129ndash136 2011

[25] M J Caterina A Leffler A B Malmberg et al ldquoImpaired noci-ception and pain sensation in mice lacking the capsaicin recep-torrdquo Science vol 288 no 5464 pp 306ndash313 2000

[26] H R Koerber S LMcIlwrath J J Lawson et al ldquoCutaneous C-polymodal fibers lacking TRPV1 are sensitized to heat followinginflammation but fail to drive heat hyperalgesia in the absenceof TPV1 containing C-heat fibersrdquoMolecular Pain vol 6 no 582010


Start EndEA

2min

(a)

Start EndEAVehicle ip CZP ip

2min5min5min

(b)

Figure 1 Experimental procedure (a) Time scale of stimulation in the wild-type and TRPV1minusminus groups (b) Time scale of stimulations in thecapsazepine (CZP) injection group

the regulation of gastrointestinal motility We previouslyreported themodulatory effects of EA on gastricmotility [16]Given the emerging role of TRPV1 receptors in mediatingsensory and visceral functions the aim of the present studywas to further elucidate the mechanism of EA-mediatedgastric motility modulation and to confirm whether TRPV1was involved in this mechanism

2 Materials and Methods

21 Animals TRPV1minusminus mice (119899 = 30 male 22ndash28 gB6129X1-TRPV1tm1JulNJU J003770) and their wild-typecounterparts (WT 119899 = 60 male 22ndash28 g) were purchasedfrom Model Animal Research Center of Nanjing University(Nanjing China) Food and water were made available adlibitum and the animals were housed under controlled envi-ronmental conditions (22∘C 40ndash60 relative humidity12-h alternate lightdark cycles) All experimental manip-ulations were undertaken in accordance with the NationalInstitutes of Health Guide for the Care and Use of LaboratoryAnimals and with the approval of the Scientific InvestigationBoard of the Nanjing University of Traditional ChineseMedicine Nanjing China

22 Experimental Groups Capsazepine injections were usedin 30 of the 60WTmice (CZP group) but not in the remain-ing 30WTmice (WT group) or the 30 TRPV1 knockoutmice(TRPV1minusminus group) Each of these three groups was dividedinto three subgroups of 10mice each and the three subgroupsof each group were subjected to EA stimulation at a differentintensity (1 2 or 4mA)

23 Experimental Procedure The animals were fasted over-nightwith free access towater and anesthetizedwith urethane(12 gkg ip U2500 Sigma USA) The trachea was cannu-lated to keep the respiratory tract patent and gastric motilitywas recorded using a previously described method [17] Asmall incision was made in the duodenum about 1-2 cmfrom the pylorus A small balloon made of flexible condomrubber was inserted into the pyloric area via incision Thepressure in the balloon was measured with a transducer(YP200 Chengdu Instrument Factory Chengdu China)and recorded with a physiological signal-acquisition system(RM6240 Chengdu Instrument Factory) for further analysisDuring the experiment the temperature of the animal wasmaintained at 37∘C plusmn 05∘C using an electric heating board

The experimental procedure in the WT and TRPV1minusminusgroups is shown in Figure 1(a) The time scale of eachstimulation in the capsazepine injection group is shown in

Figure 1(b) Capsazepine (05mgkg ip C191 Sigma USA)was dissolved in a vehicle (1 dimethyl sulfoxide D8418Sigma USA)

24 EA Stimulation A pair of needle electrodes (diameter03mm) were inserted approximately 5mm deep into theZhongwan point (CV12) which is located at the center of theabdomen in the midline of the body [17] The EA intensitywas set as 1 2 or 4mA with alternating frequencies of 2Hzand 15Hz for 2min

25 Statistical Analysis Data were analyzed using SPSS 170software (SPSS Chicago USA) Differences before and aftertreatment were compared using a paired-sample 119905-test andthose between two groups were compared using an inde-pendent-sample 119905-test Comparison among groups was per-formed using analysis of variance 119875 lt 005 was consideredstatistically significant All data were expressed as mean plusmn SE

3 Results

31 Gastric Motility In the resting condition (prior to EA)rhythmic gastric contractions at a frequency of 3ndash6min wereobserved in the TRPV1minusminus and WT mice and the contractileamplitude of the rhythmic waves was approximately 005ndash03 kPa when balloon pressure was maintained at about 04ndash06 kPa by filling the balloon with 01ndash02mL warm waterInjection of 05mgkg capsazepine ip caused no change ingastric movement or amplitude

32 Gastric Response to Different Intensities of EA Stimulationat CV12 InWTmice EA stimulation at CV12 at an intensityof 1mA (119899 = 10) produced no significant effect on gastricmotility (Figure 2(a)) In contrast EA stimulation at 2mAslightly inhibited gastric motility while stimulation at 4mAstrongly inhibited it Thus the inhibition of gastric motilityby EA stimulation was intensity dependent

33 TRPV1 Is Involved in Gastric Motility Modulation byEA Stimulation To determine the mechanism underlyingthe inhibitory effect of EA stimulation at CV12 we usedcapsazepine a specific antagonist of TRPV1 In theWTmicesignificant inhibition of gastric motility was obtained afterEA stimulation at 2 and 4mA but not at 1mA moreoverthis inhibitory effect was intensity dependent being greater at4mA than at 2mA (Figure 4(e)) After capsazepine injectionEA stimulation at 1mA (119899 = 10) produced no significantinhibition while that at 2mA produced mild inhibition(Figure 3(a)) however the effect of EA stimulation at 4mA


0

01

02

03

04

05

06

07

08

BaselineEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA


(a)

(kPa

)

0

1

EA 1mA 120 s

(b)

(kPa

)

0

1

EA 2mA 120 s

(c)

(kPa

)

0

1

EA 4mA 120 s

(d)


0

01

02

03

04

05

06

07

08

BaselineVehicle

CZPEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA


(a)

0

1

(kPa

)


(b)

0

1


(kPa

)

(c)

0Vehicle CZP

1

EA 4mA 120 s

(kPa

)

(d)



00102030405060708

Gas

tric

pre

ssur

e (kP

a)

Baseline EA

1mA 2mA 4mA


(a)

0

1

(kPa

)

EA 1 mA 120 s

(b)

(kPa

)

0

1

EA 2 mA 120 s

(c)(k

Pa)

0

1

EA 4 mA 120 s

(d)

WTCZP

Gas

tric

pre

ssur

e (

)

1mA 2mA 4mA

ΔΔΔΔ

ΔΔ

minus2000

minus1500

minus1000

minus500

000

TRPV1minusminus

(e)



4 Discussion








Acknowledgments



References





























0

01

02

03

04

05

06

07

08

BaselineEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA


(a)

(kPa

)

0

1

EA 1mA 120 s

(b)

(kPa

)

0

1

EA 2mA 120 s

(c)

(kPa

)

0

1

EA 4mA 120 s

(d)


0

01

02

03

04

05

06

07

08

BaselineVehicle

CZPEA

Gas

tric

pre

ssur

e (kP

a)

1mA 2mA 4mA


(a)

0

1

(kPa

)


(b)

0

1


(kPa

)

(c)

0Vehicle CZP

1

EA 4mA 120 s

(kPa

)

(d)



00102030405060708

Gas

tric

pre

ssur

e (kP

a)

Baseline EA

1mA 2mA 4mA


(a)

0

1

(kPa

)

EA 1 mA 120 s

(b)

(kPa

)

0

1

EA 2 mA 120 s

(c)(k

Pa)

0

1

EA 4 mA 120 s

(d)

WTCZP

Gas

tric

pre

ssur

e (

)

1mA 2mA 4mA

ΔΔΔΔ

ΔΔ

minus2000

minus1500

minus1000

minus500

000

TRPV1minusminus

(e)



4 Discussion








Acknowledgments



References





























00102030405060708

Gas

tric

pre

ssur

e (kP

a)

Baseline EA

1mA 2mA 4mA


(a)

0

1

(kPa

)

EA 1 mA 120 s

(b)

(kPa

)

0

1

EA 2 mA 120 s

(c)(k

Pa)

0

1

EA 4 mA 120 s

(d)

WTCZP

Gas

tric

pre

ssur

e (

)

1mA 2mA 4mA

ΔΔΔΔ

ΔΔ

minus2000

minus1500

minus1000

minus500

000

TRPV1minusminus

(e)



4 Discussion








Acknowledgments



References

































Acknowledgments



References




























electroacupuncture stimulation at cv12 inhibits gastric ......electroacupuncture stimulation at cv12...

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