In the West, many biomedical researchers – and, more importantly, many physicians – question whether acupuncture merely stimulates so-called nonspecific or placebo effects in the body. Non-specific effects, a.k.a. subject-expectancy effects, a.k.a. placebo effects, occur when a patient's symptoms are altered in some way (either alleviated or exacerbated) by an otherwise inert treatment due to the individual expecting or believing that the treatment will work. Some people consider this to be a remarkable aspect of human physiology.¹ Others consider the effect to be an illusion arising from the way medical experiments are conducted. For instance, the entry for "acupuncture" in the online encyclopedia Wikipedia has this to say in its second paragraph:

Whether acupuncture is efficacious or a placebo has been the subject of ongoing scientific research. Scientists have conducted reviews of existing clinical trials according to the protocols of evidence-based medicine; some have found efficacy for headache, low back pain, and nausea, but for most conditions have concluded that there is insufficient evidence to determine whether or not acupuncture is effective.²

However, much of that opinion is based on equivocal human research, where nonspecific or placebo effects cannot easily be eliminated from the study design. On the other hand, in China, a relatively large amount of research on acupuncture is carried out on animal models. This has two advantages. First, it eliminates most, if not all, the issues surrounding nonspecific effects, and secondly, it allows researchers to study changes in biochemical markers and tissues that would not be possible in living human beings. Therefore, in my column this month, I would like to present a review of some recently published studies on acupuncture in animal models. I think this research makes it more difficult to maintain that acupuncture simply works via nonspecific effects or placebo.

1. Zheng Ling, et al. The influence of acupoint application & moxibustion pretreatment on serum IL-6, testosterone, growth hormone, and cortisol levels in rats with adjuvant arthritis in the early & secondary stages. Zhen Ci Yan Jiu (Acupuncture Research). 2006; 6: 330-332.

The objective of this study was to observe the effects of acupoint application and moxibustion pretreatment on serum inflammatory cytokines and hormones in rats with adjuvant arthritis in the early and secondary stages. To this end, 40 Wistar rats were randomly divided into normal, early-stage model, secondary-stage model, early-stage pretreatment, and secondary-stage pretreatment groups. An arthritis model was created by injecting Freund's complete adjuvant (FCA, 0.1ml) into the rats' hind paws. After removing the hair and before injecting FCA, respectively, a plaster made from Yin Yang Huo (Herba Epimedii) and other Chinese medicinals was applied at acupoint Da Zhui (GV 14). Then moxa cones were placed on top of this plaster and burned. This was done once every other day for a total of eight times. Rats in the four early-stage and secondary-stage groups were sacrificed on the third and 16th days after injection of FCA, respectively. In addition, those rats in the normal control group were also sacrificed in order to collect blood samples. The contents of serum IL-6, testosterone (T), growth hormone (GT), and cortisol (CORT) were assayed, respectively, with radioimmunoassay according to the instructions in the reagent kits. In terms of outcomes, compared with the normal group, the contents of serum IL-6, GH, and CORT in the early-stage model and secondary-stage model groups increased significantly (P > 0.01), and those in the early-stage pretreatment, while serum T and GH in the early-stage and secondary-stage pretreatment groups also increased remarkably (P > 0.05, 0.01). However, the T level in the early-stage model group decreased significantly (P < 0.05) in comparison to the corresponding model groups, while the T level in the early-stage and secondary-stage pretreatment groups increased significantly (P > 0.05, 0.01) at the same time as serum IL-6 and GH decreased markedly (P < 0.05). Thus, the study concluded that preconditioning of acupoints by medicinal application and moxibustion at Da Zhui (GV 14) can effectively suppress arthritis-induced increases in serum IL-6 and GH and decrease T to modulate inflammatory cytokines and hormones in adjuvant arthritis rats.

2. Sheng You-xiang, et al.The effects of electroacupuncture on deltoid opioid receptor mRNA expression in the local focus tissues of arthritis rats. Zhen Ci Yan Jiu (Acupuncture Research). 2006; 6: 333-336.

The objective of this study was to observe the effects of electroacupuncture (EA) on deltoid opioid receptor gene expression in inflammatory tissue in adjuvant arthritis rats in order to study the underlying peripheral mechanism of EA analgesia. Therefore, 32 SD rats were randomized into control, model, EA (model + EA), and normal + EA (normal animal) groups with eight animals per group. Electroacupuncture was then applied at 2-4 V, 20-100 Hz to Xuan Zhong (GB 39) and Kun Lun (Bl 60) for 20 minutes once per day for six days. Arthritis model was induced by injecting Freund's complete adjuvant (FCA, 0.1 ml) in the rat's hind paw. The latency of radiant-heat irradiation-induced leg withdrawal was considered the pain threshold. At the end of the experiment, the rats were anesthetized with 3% phenobarbitol (30 mg/kg) and then transcardiacally perfused with 4% paraformaldehyde and 0.1% diethylpyrocarbonate. This was then followed by taking a sample of the focal tissue. After routine treatment, the tissue samples were embedded in paraffin, cut into sections, and processed with in situ hybridization histochemistry for the observance of delta opioid receptor mRNA. Analysis of these results showed that, compared with the control group, the pain threshold of the model group declined significantly (P < 0.01), while comparison between the EA and model groups and between normal + EA and model groups showed that the pain threshold of the two EA groups was significantly higher (P > 0.01). Similarly, the pain threshold of the normal + EA group was also significantly higher than that of the EA group (P > 0.01), but no significant difference was found between the control and EA groups in pain threshold (P < 0.05). This indicated that EA can raise the pain threshold in both arthritis and normal rats. Secondly, compared with the model group, the number of delta opioid receptor mRNA expression-positive cells in the EA group was remarkably higher (P > 0.01), thus showing marked up-regulation of delta opioid receptor mRNA expression in the focal tissue after EA. Hence, it was concluded that EA has a definite analgesic effect in arthritis rats that may be related to its effect of up-regulating the expression of delta opioid receptor mRNA expression.

3. Zhong Shu-bo, et al. The positive effect of electroacupuncture on mitochondrial function in rats with temporal cerebral ischemia. Zhen Ci Yan Jiu (Acupuncture Research). 2006; 6: 337-341.

The objective of this study was to explore the protective effect of electroacupuncture (EA) on the activity of cerebral cytochrome C oxidase and mitochondrial DNA (MtDNA) in cerebral ischemia-reperfusion rats (CI/R). In this study, 48 male SD rats were evenly randomized into sham-operation, sham-operation + EA, model, and model + EA groups with 12 animals in each group. The CI/R model was induced by middle cerebral artery occlusion (MCAO) under anesthesia (7% chloral hydrate, 1 ml/200 g). Electroacupuncture at 1-4 mA and 5-20 Hz with dense-dispersed waves was applied to Shui Gou (Gv 26) and Bai Hui (GV 20) for 30 minutes at first. Stimulation was suspended for 15 minutes and then reapplied for another 30 minutes. The rats in each group were sacrificed, and their right brain hemisphere was removed. Then the cerebral mitochondria were isolated by differential dentrifugation. Mitochondria suspension (1 mg/ml protein) were frozen and thawed three times at a temperature of -20°C. The activity of complex IV (cytochrome C oxidase) was estimated by spectrophotometry and calculated. MtDNA was isolated and purified according to the instruction in the DNA isolation kit. The concentration of MtDNA was determined by spectrophotometry. DNA damage levels were measured by agarose gel electrophoresis. Based on all this, it was found that, compared to the sham-operation and sham-operation + EA groups, the activity of cytochrome C oxidase was significantly lower in the model group (P < 0.01), while compared to the model group, the activity of this enzyme in the model + EA group was markedly higher (P > 0.01), thus indicating an increase in the activity of cytochrome C oxidase after EA. There was no significant difference between the shame and sham + EA groups in the activity of this oxidase. MtDNA in the core of the brain focus and penumbra region were both damaged seriously. Although, the extent of DNA damage in the penumbra region was reduced after EA treatment, it was not reduced in the core region. Therefore, it was concluded that EA can reduce the injury to mitochondrial function in MCAO rats. Further, this reduction may be due to EA's effect of reducing oxidative stress of the affected brain cells.

4. Yi Shou-xiang, et al. The effects of moxibustion on the proliferation & apoptosis of gastric mucosal cells and their relationship with heat shock protein expression in stress gastric ulcer rats. Zhen Ci Yan Jiu (Acupuncture Research). 2006; 5: 259-263.

The purpose of this study was to observe the effects of moxibustion at Zu San Li (St 36) and Liang Men (St 21) on the proliferation and apoptosis of gastric mucosal cells and the relationship between the effect of moxibustion and the expression of heat shock protein 70 (HSP70) mRNA so as to explore the underlying molecular and biological mechanism of moxibustion in accelerating the repair of injured gastric mucosa. Therefore, 60 SD rats were randomly assigned to control, model, acupoint moxibustion, and non-acupoint moxibustion groups, with 15 animals in each group. A gastric ulcer model was established by fasting for 24 hours followed by forced water immersion at 20°C for ten hours. Moxibustion was applied unilaterally to Zu San Li (St 36) and Liang Men (St 21) or at a non-acupoint approximately one centimeter lateral to each of these two points for approximately 30 minutes or four cones. This was done once per day for eight successive days. At the end of the experiment, the rats' gastric mucosa was sampled in order to examine the gastromucosal injury index (ulcer index, UI, via GUTH's method), apoptosis index (via apoptosis reagent kit), proliferating cell nuclear antigen (PCNA, via immunohistochemical method) activity, transforming growth factor alpha (TGF-alpha) content (via radioimmunoassay), and HSP70 mRNA expression (reverse transcriptase-polymerase chain reaction, RT-PCR) separately. These analyses found that, compared with the control group, gastric mucosa UI, apoptosis index, and HSP70 mRNA expression of the model group increased significantly (P > 0.01, 0.05), while TGF-alpha content and PCNA numerical density decreased markedly (P < 0.01, 0.05). In comparison with the model group, UI and apoptosis index of the acupoint moxibustion group decreased significantly (P < 0.01, 0.05), and the TGF-alpha level, PCNA numerical density, and HSP70 mRNA expression of the acupoint moxibustion group increased markedly (P > 0.01). No significant differences were found between the model and non-acupoint moxibustion groups in terms of UI, TGF-alpha levels, and apoptosis index, or between the acupoint and non-acupoint groups in terms of PCNA numerical density (P < 0.05). Thus, it was concluded that moxibustion at Zu San Li (St 36) and Liang Men (St 21) has a protective effect on the gastric mucosa in stress gastric ulcer rats that is closely related to its action of promoting the synthesis of TGF-alpha and the proliferation of the gastromucosal cells, suppressing gastromucosal apoptosis, and up-regulating HSP70 mRNA expression.

5. Wu Zi-jian, et al. The effects of electroacupuncture on the signal transduction of G-protein in rat ischemic myocardial cells. Zhen Ci Yan Jiu (Acupuncture Research). 2006; 5: 264-267.

The objective of this study was to analyze the effects of electroacupuncture (EA) on myocardial cellular signal transduction of G-protein in myocardial ischemia (MI) rats in order to explore the molecular pathways of EA against MI injury. Therefore, 20 male SD rats were randomized into normal, model, EA-normal, and EA-model groups, with five rats in each group. An MI model was established by occlusion of the descending anterior branch of the left coronary artery under anesthesia to 10% chloral hydrate (0.36 ml/100 g). Electroacupuncture at 1.3 mA, 2 Hz, and 300 µs in duration of pulse was applied to Shen Men (Ht 7) for 20 minutes once per day for three days successively. Three days later, a myocardial tissue sample was taken for abstracting related G-proteins and corresponding genes by using gene chip technology. Accordingly, in comparison with the model group, after EA at Shen Men (HT), 782 differentially expressed genes were found, of which 328 were up-regulated and 454 were down-regulated. Compared to the normal group, 426 differentially expressed genes were found in the EA-normal group. Among them, 217 genes were up-regulated, and the other 209 genes were down-regulated in expression. Further analysis showed that 21 genes were associated with the G-protein signal transduction pathway, 15 genes had an apparent expression in all four groups, four genes were significantly unchanged, and the remaining two genes were differentially expressed. Of these two differentially expressed genes, Gng8 displayed weaker and stronger expression in EA-normal and EA-model groups, respectively, and had no expression in normal and model groups. This suggests that these differences in Gng8 expression were related EA at Shen Men (HT 7). Gene Prkar2b, the other of these last two genes, showed no expression in normal and EA-normal groups, but its expression was detectable in model and EA-model groups. This suggests that its expression is related to MI. Thus it was concluded that 1) EA at Shen Men (Ht 7) can affect the gene expression pathway, and 2) Gng8 and Prkar2b may play an important role in the EA-induced protective action on MI.

Conclusion
I believe that these animal studies on acupuncture and moxibustion strongly suggest that acupuncture's therapeutic effects are not just related to so-called nonspecific effect or placebo. Further, these five studies came from just two issues of a single Chinese medical journal. Altogether, there were 13 such animal studies in these two issues. Now consider how many issues of this single journal have been published with many such animal studies. In addition, remember that other such acupuncture animal studies are routinely published in other Chinese acupuncture journals. In other words, there appears to be a very large literature (albeit somewhat sequestered in Chinese) on acupuncture's effects in animal studies. I think that if more Westerners were aware of the existence of this body of literature, they would not be so quick as to dismiss acupuncture's effects as simply due to placebo.

Copyright © Blue Poppy Press, 2007. All rights reserved.

References

Keywords: Chinese medicine, acupuncture, moxibustion, electroacupuncture, acupuncture efficacy, placebo, animal studies