Review Article

Central and Peripheral Mechanism of Acupuncture Analgesia on Visceral Pain: A Systematic Review

Table 4

Visceral hypersensitivity models in animal studies (other models).

Author
(year)
Model
(animal, gender, number)
Acupuncture groupsControl groupsOutcomesResults
AcupunctureAcupoints
number, duration
ControlAcupoints
number, duration

(1) Du et al. (1976) [52]Splanchnic nerve stimulation (cat, -,-)(A) Model+EA (25/70/100Hz)(A) GB31, 34, LI11, TE5
-
--(1) VSRWithin group
(1) (A): inhibited
(2) Zhang et al. (1989) [53]Splanchnic nerve stimulation (cat, -, total 35)(A) Model+EA (5Hz)(A) PC6
1,3-5min
(B) Model+Morphine
(C) Model+EA+NAL
(C) PC6
1, 3-5min
(1) C-CEPs
(2) A-CEPs
Within group
(1) (A), (B): reduced amplitudes
(2) (A), (B): reduced amplitude of late component
(3) Guoxi (1991) [54]Splanchnic nerve stimulation (cat, m, total 219)(A) Model+EA(A) ST36
-
--(1) Electrical activities in thalamusWithin group
(1) (A): inhibited in 45 out of 48 neurons
(4) Shu et al. (1994) [48]Splanchnic nerve stimulation (Wistar rat, m, 3/4/4)(A) Model+EA(A) ST36, SP6
-
(B) Control
(C) Model
-(1) Pain threshold
(2) Glucose metabolic rate
Within group
(1) (A): increase after treatment
Between groups
(2) (A)<(C): TDH, LC, ventral PAG, CPC, HL, Hippo, CP, NRD, NCS, TPV, ACC, accumbens, NSL, SC
(C)<(A): LDH, NRM, NRG, PAG
(B)<(C): NRM, PGL, LC, NRG, HA, CCGM
(5) Cai et al. (1994) [57]Splanchnic nerve stimulation (rabbit, m/f, 8/4/6/6/7/9/6/6)(A) Model+EA (25Hz)+SAL(A) EX-B2 (T12,L1,L2)
1, 30min
(B) Model+SAL
(C) Model+ MCP
(D) Model+EA (25Hz)+MCP
(E) Model+EA+MCP+SAL
(F) Model+EA+MCP+APO
(G) Model+EA+MCP+SKF38393
(H) Model+EA+MCP+LY171555
(D)-(H) EX-B2
1, 30min
(1) Pain threshold
(2) DA in CSF
(3) DOPAC in CSF
(4) HVA in CSF
Within group
(1) (A), (C), (D), (F): elevated compared to baseline
(4) (A), (C): elevated compared to baseline
Between groups
(1) (A), (C)<(D); (B)<(C); (F), (G), (H)<(E)
(4) (A),(C)>(B)
(6) Kwon et al. (2001) [56]Acetic acid injection (ICR mice, m, 10-20/group)(A) Model+BV
(B) Model+BV+NAL
(C) Model+BV+Yo
(A) CV12
1, -
(D) Model+BV
(E) Model+SAL
(D) non-acupoint
1, -
(1) Abdominal stretches
(2) c-Fos in spinal cord, NTS
Between groups
(1) (A), (D)<(E)
(2) (A)<(E)
(7) Yu et al.
(2008) [55]
Acetic acid injection (mice, m/f, 12/group)(A) WT Model+MA
(B) Connexin 43 gene knockout HT Model+MA
(A),(B) CV12, ST36
1, 30min
(C) WT control
(D) HT control
(E) WT model
(F) HT model
-
-
(1) c-Fos in the spinal dorsal hornBetween groups
(1) (A)<(E), (A)<(B)
(8) Yu et al.
(2008) [22]
Acetic acid injection (mice, m/f, 18/group)(A) Model+WT MA
(B) Connexin 43 gene knockout HT ++Model+MA
(A),(B) CV12, ST36
1, 30min
(C) WT control
(D) HT control
(E) WT model
(F) HT model
-
-
(1) Latency of writhing response
(2) Number of writhing response
(3) β-endorphin in hypothalamus
(4) Plasma PGE2
Between groups
(1), (3) (A)>(E), (A)>(B)
(2), (4) (A)<(E), (A)<(B)
(9) Liu et al. (2010) [23]Acetic acid injection (SD rat, m/f, 6/group)(A) Model+EA (2/20Hz)
(B) Model+EA+Snake venom
(C) Modal+EA+SAL
(A)-(C) ST2
1, 20 min
(D) Control
(E) Model
(F) Model+EA+ION transection
(F) ST2
1, 20 min
(1) Abdominal muscular contractions
(2) c-Fos expression in the NTS
(3) c-Fos expression in the PTN
Between groups
(1), (2) (A),(E)>(D); (A),(B),(C)<(E), (A)<(F)
(3) (A),(B),(C)>(E), (A),(B),(C)>(F)
(10) Liu et al. (2011) [31]Acetic acid injection (SD rat, -, -)(A) Model+EA (2/20Hz, 1.0mA)
(B) Model+EA (2/20Hz, 2.0mA)
(C) Model+ EA (2/20Hz, 4.5mA)
(D) EA (2/20Hz)
(E)-(G) Model+EA (2/20Hz)
(A)-(E) ST2
(F) GB14
(G) ST6
1, 20min
(H) Control
(I) Model
(J) Model+Sham EA (ns)
(K) Model+EA (2/20Hz)
(J) ST2
(K) non-acupoint
1, 20min
(1) c-Fos
(2) Abdominal contractions
Within group
(1) (D): in the NTS, CPTN, PTN, postrema, DMN of the vagus, RF (blocked by infraorbital nerves transaction pretreatment in PTN)
(1) (B), (C), (E), (G), (K): inhibited in NTS
(1) (B)-(E), (G), (K): increased in PTN
(1), (2) (E): infraorbital nerves transaction and capsaicin pretreatment inhibited the effect of EA on reduced (1) and (2)
Between groups
(2) (D), (E), (G), (H), (K)<(I)
(B), (C)<(A), (I), (K)
(11) Gong et al.
(1992) [50]
Antimonium potassium tartrate injection (Wistar rat, m/f, 15/10/7/-/12/8/9/8/6/6/10/8/15/15)(A) Model+EA (45/12.5Hz)
(B) Model+EA (45/12.5Hz)
+electrical stimulation of PVN
GV26, CV24
1, 20min
(C) Control
(D) Model
(E) Model+Sham EA (ns)
(F) Model+EA+sham stimulation of PVN
(G) Model+EA+lesion of PVN
(H) Model+EA+sham lesion of PVN
(I) Model+EA+vasopressin antagonist
(J) Model+EA+SAL
(K) Model+EA+vasopressin antiserum
(L) Model+EA+normal serum
(M) Model+EA+vasopressin antagonist
(N) Model+EA+SAL
(E)-(N) GV26, CV24
1, 20min
(1) Writhing responseBetween groups
(1) (A)<(E), (B)<(F), (G)>(H), (I)>(J), (K)>(L)
(12) Xu et al. (2010) [59]Formalin injection (SD rat, m, 8/group)(A) EA (20Hz, ~1mA)
(B) Model+EA
(20Hz, ~1mA)
(A), (B) EX-B2 (L3, 6)
1, 20min
(C) Control
(D) Model
-(1) Visceral pain behavior
(2) p38 in colon, spinal dorsal horn
(3) c-Fos in colon, spinal dorsal horn
(4) Plasma β-endorphin
(5) SP in colon
Between groups
(1) (B)<(D)
(2), (3), (5) (B), (C)<(D)
(4) (C)<(D)<(B)
(13) Rong et al.
(2005) [44]
CRD (SD rat, m, total 67)(A) Model+non receptive field MA (2-3Hz)
(B) Model+receptive field MA
(A) ST36 (contr)
(B) ST36 (ips)
1, 30s
(C) Model
(D) Model+non receptive field pinch
(E) Model+ receptive field pinch
(F) Model+hot water on tail (non receptive filed)
(G) Model+ non receptive field MA+acute freeze of spinal cord
(H) Model+acute freeze of spinal cord
(G) ST36 (contralateral)
1, 30s
(1) Electrical activities of spinal dorsal horn WDR neurons of L1-L3Within groups
(1) (A), (D): decreased
(B), (G), (H): increased
Between groups
(1) (A),(D)<(C); (A)<(G)
(14) Rong et al.
(2005) [24]
CRD (SD rat, -, 17/17/9/15/9)(A), (B) Model+MA (2Hz)(A) ST36 (contr)
(B) ST36 (ips)
1, 30s
(C) Pinch (contr)
(D) Pinch (ips)
(E) Model
-(1) Electrical activities in spinal dorsal hornBetween groups
(1) (A), (C)<(E) ((A)<(E) effect blocked after spinalization)
(15) Zhang et al. (2009) [28]CRD (SD rat, m, 58)(a), (b) Model+EA (2Hz, 1mA)(a) ST36 (contr)
(b) ST36 (ips)
1, 320s
(c) Model
(d) Model+EA (2Hz, 1mA, 0.5ms)
(e) Model+EA (100Hz, 1mA, 0.5ms)
(c)-(e) center of receptive field
1, 320s
(1) Electrical activities in thalamusBetween groups
(1) (d), (e)<(c) (e)<(d) (d)<(a), (b)
(16) Chen et al. (2010) [51]CRD (Wistar rat, m, 9/group)(A) Model+EA
(B) Model+EA
(C) Model+EA (2/15Hz, 2mA)
(A) ST36
(B) PC6
(C) LR3
1, 15min
(D) Control
(E) Model+Sham EA (non-acupoint, 2/15Hz, 2mA)
(E) non-acupoint
1, 15min
(1) MAP
(2) HR
(3) HRV HF
(4) LF
(5) LF/HF
Within group
(2) (A), (B) decreased
Between groups
(1) (A),(B)<(C),(D),(E)
(4) (A),(B),(C)<(D)
(5) (A),(B)<(D)
(17) Liu et al. (2014) [35]CRD (SD rat, m, 62)(a)-(c) Model+EA (10Hz, 2mA)(a) ST36
(b) PC6
(c) Auricular acupoint (heart)
1, 30s
--(1) Electrical activities in NTSWithin group
(1) (a), (b), (c): reduced in 5-10 neurons and increased in 2 neurons among 21 excited neurons by CRD
reversed in 9-15 neurons among 24 inhibited neurons by CRD
(18) Yu et al. (2014) [36]CRD (SD rat, m, 10-11/group)(a) Model+EA (15Hz, 1.5mA)
(b) Model+EA (15Hz, 6mA)
(c) Model+EA (15Hz, 4mA)
(a)-(c) ST36, 37
2, 30s
(d) Model-(1) Electrical activities of wide dynamic range neurons
(2) Electrical activities of SRD neurons
Within group
(1) (a), (b): increased after treatment and CRD
(d): increased
(2) (c), (d): significant responses
(a), (b): increased after CRD
(19) Li et al. (2014) [37]CRD (SD rat, f, 8/7/7/7)(A) Model+auricular EA (25Hz, 0.8mA)(A) Auricular acupoints (stomach, small intestine)
1, 30min
(B) Control
(C) Model
(D) Model+sham EA
(D) no vagal innervation points
1, 30min
(1) VMR
(2) mRNA of 5-HT1a receptor in colon
(3) mRNA of 5-HT1a receptor in raphe nuclei
Within group
(1) (C): increased
Between groups
(1) (B)<(A), (C), (D)
(1), (2) (A)<(C)
(3) (A)<(C), (D)
(20) Yu et al. (2014) [47]CRD (SD rat, m, 22)(a) preEA+Model+EA (15Hz, 1mA)
(b) preEA+Model+EA (15Hz, 4mA)
(c) preEA+Model+EA (15Hz, 7mA)
(d) preEA+Model+EA (15Hz, 10mA)
(a)-(d) ST36 (ips)
2, 30s
--
-
(1) Electrical activities of WDR in lumbar spinal cordWithin group
(1) (a), (b), (c), (d): increased
(21) Liu et al. (2015) [38]CRD (SD rat, m, 8/group)(A) Model+EA (2/100Hz)(A) ST37
7, 20min
(B) Control
(C) Model
(D) Model+sham EA (ns)
(D) ST37
7, 20min
(1) AWR
(2) CRH in colon
(3) CRH in spinal cord, hypothalamus
(4) mRNA of CRH in colon, spinal cord, hypothalamus
Between groups
(1) (A), (B)<(C); (A)<(D)
(2) (A), (B), (D)<(C)
(3) (A), (B)<(C),(D) (except (A)<(D) in the spinal cord)
(4) (A), (B)<(C); (B)<(D)<(C) (only in hypothalamus)
(22) Rong et al. (2015) [40]CRD (SD rat, m, 26)(a) Model+EA (20Hz)(A) ST36, 37
2, 30s
(b) Model-(1) Discharge frequency of VPL neurons in thalamusWithin group
(1) (a): increased after CRD
(b): increased
(23) Iwa et al.
(2005) [58]
Rectal distension (Dog, f 4, 6/group)(A) Model+EA (10Hz)(A) ST36
1, 30min
(B) Model+EA
(C) Model+EA+NAL
(D) Model+EA+NAL methiodide
(B) BL21
(C), (D) ST36
1, 30min
(1) Arterial
blood pressure
Within group
(1) (A), (D): decreased after treatment
(24) Lin et al. (2009) [45]Gastric distension (SD rat, m, 10/group)(A) Model+EA (2Hz, 1-3mA)
(B) Model+EA (100Hz, 1-3mA)
(A),(B) ST36
7, 30min
(C) Control
(D) Model
(E) Sham model
-
-
(1) Pain score
(2) β-endorphin in hypothalamus
(3) SP in hypothalamus
Within group
(1) (A), (B) decreased
Between groups
(1) (B)>(A)>(D)>(C),(E)
(2),(3) (A)>(B)>(D)>(C),(E)
(25) Sun et al. (1991) [49]Somatic and visceral noxious stimuli (Wistar rat, m/f, 23/28/-/16)(A) Model+EA (6v, 8Hz)(A) ST36
1, 15min
(B) Model
(C) Model+Morphine
(D) Model+Morphine+NAL
-
-
(1) Discharge of PEN in VPN
(2) Discharge of PIN in VPN
Within group
(1) (A): reduced
(2) (A): enhanced
(26) Lorenzini et al. (2010) [30]Cystitis (SD rat, m, total 48)(A) Cystitis+PWL(A)-(F) ST36, TE5
Various
(B) Cystitis-(1) Urinary bladder weight, mucosal erosion, ulceration, edema, petechial hemorrhages, thickness of bladder wall
(2) Visceral pain behavior
Within group
(1), (2) (A), (B): increased
(27) Yang et al. (2010) [46]Visceral traction (SD rat, m, 10/group)(A) Model+ LA (650nm, 10mW)(A) ST36
1, 30min
(B) Sham model
(C) Model
(D) Model+Moxa
(D) ST36
1, 30min
(1) Pain score
(2) Systolic pressure
(3) AChE
(4) SP
(5) LEK
(6) Positive index of c-Fos protein
(7) Positive index of GFAP
Between groups
(1), (3) (A),(B),(D)<(C)
(2) (A),(B)<(C)
(4) (B)<(A)<(D)<(C)
(5) (A)>(B),(C),(D)
(6), (7) (B)<(A),(D)<(C)

Group written in lowercase letters (e.g., (a), (b), and (c)): different treatments in the same population, unless stated otherwise. Group written in capital letters (e.g., (A), (B), and (C)): different treatments in different population.
ACC: anterior cingulate cortex; A-CEPs: cortical evoked potentials of A-fibers; AChE: acetylcholinesterase; APO: apomorphine; AWR: Abdominal withdrawal reflex; BL: Bladder Meridian; BV: bee venom; C-CEPs: cortical evoked potentials of C-fibers; CCGM: centralis corpus geniculatum medialis; contr: contralateral; CP: caudate putamen; CPTN: caudal spinal trigeminal nucleus; CRD: colorectal distension; CRH: corticotropin-releasing hormone; CSF: cerebrospinal fluid; CV: Conception Vessel Meridian; DA: dopamine; DMN: dorsal motor nucleus; DOPAC: dopaceticacid; EA: electro-acupuncture; f: female; GB: Gall Bladder Meridian; GFAP: glial fibrillary acidic protein; GV: Governing Vessel Meridian; HA: hypothalamic arcuatus; HF: high frequency heart rate variability; Hippo: hippocampus; HL: habenulae lateralis; HR: heart rate; HRV: heart rate variability; HT: heterozygote; HVA: homovanillic acid; ION: infraorbital nerve; ips: ipsilateral; IT: intrathecal injection; L: lumbar vertebrae; LA: laser acupuncture; LC: locus coeruleus; LDH: lumbar dorsal horns; LEK: leu-enkephalin; LF: low frequency heart rate variability; LI: Large Intestine Meridian; LR: Liver Meridian; m:male; MA: manual acupuncture; mA: milliampere; MAP: mean arterial pressure; MCP: metoclopramide; min: minutes; Moxa: moxibustion; mRNA: messenger ribonucleic acid; ms: milliseconds; NAL: naloxone; NCS: nucleus centralis superior; NRD: nucleus raphe dorsalis; NRG: nucleus reticular gigantocellularis; NRM: nucleus raphe magnus; ns: not stimulated; NSL: nucleus septal lateralis; NTS: nucleus tractus solitarii; PAG: periaqueductal gray; PC: Pericardium Meridian; CPC: centromedian-parafascicula; PEN: pain-excitation neurons; PGE2: prostaglandin E2; PGL: paragigantocellularis lateralis, PIN: pain-inhibitory neurons; PTN: paratrigeminal nucleus; PVN: paraventricular nucleus; PWL: pulsed wave laser; RF: reticular formation; SAL: saline; s: seconds; SC: somatosensory cortex; SD: Sprague Dawley; SP: substance P; SRD: subnucleus reticularis dorsalis; ST: Stomach Meridian; T: thoracic vertebrae; TDH: thoracic dorsal horns; TE: Triple Energizer Meridian; TPV: thalamic posterior ventralis; VMR: visceral motor response (reflex); VPL: ventralis posterior lateralis; VPN: ventral posterolateral nucleus; VSR: viscerosomatic reflex discharges; WDR: wide dynamic range; WT: wild type; Yo: yohimbine; 5-HT: 5-hydroxytryptamine receptor.