Here, we present a protocol for the application of Lingnan Fire-Needle therapy in the intervention of osteoporosis model rats.
Compared to filiform needle therapy, fire-needle therapy has both the stimulation of needles and the warming effect of heat, making it have unexpected effects on some chronic diseases and incurable diseases. Osteoporosis (OP) has a high incidence in postmenopausal women and middle-aged and elderly men, and the treatment cycle is long. According to Traditional Chinese Medicine (TCM), Lingnan fire-needle therapy has shown potential in treating osteoporosis. However, there is still a long way to go before it can be widely used. This article focuses on the application of Lingnan fire-needle therapy in the intervention of OP in rats. It covers the selection of needle tools, acupuncture point selection, positioning of rats’ bodies, and fixation methods. We also outline the steps and precautions to be taken during and after needling with fire needles. The experiment was done with three groups: a normal group, a model group, and a fire-needle group, each containing 10 rats. The rats in the fire-needle group were treated with fire-needle intervention for six sessions. After the intervention period, we collected femoral specimens and performed micro-CT scans. The results suggest that fire needling can enhance bone morphology and mineral density in OP rats. This information can serve as a methodological basis for conducting basic research on fire-needle therapy.
Chinese medicine believes that factors such as climate and environment can affect a person's physique, which in turn affects the occurrence and development of diseases. The Lingnan region of China, mainly including Guangdong, Guangxi, and Hainan Island, is located in the tropical monsoon climate region. As a result, people living in this region for a long time are prone to a form of spleen deficiency. In some cases, it spreads to the kidney and liver, leading to the prevalence of osteoporosis1. The spleen and stomach function in transporting and absorbing water and grains, which are the source of qi and blood biochemistry, while the liver helps maintain the marrows. So, bone nutrition relies on the supply of the spleen, stomach, and liver. In Chinese medicine, the kidney is capable of generating marrow and strengthening bones, and its vitality directly affects the strength and function of bones. Therefore, kidney deficiency is directly related to osteoporosis. According to TCM, liver (Gan)-kidney (Shen) deficiency and lack of essence (Jing) are the underlying causes. In some cases, malnutrition may occur due to a spleen (Pi) and stomach (Wei) deficiency or an imbalance of the two. That is, the deficiency of the liver (Gan), kidneys (Shen), spleen (Pi), and stomach (Wei) are the root causes, while external qi (Xie qi) blocks meridians and damages bones and muscles. According to the World Health Organization (WHO), OP is a medical condition characterized by low bone mass and tissue deterioration2, which is a serious concern for the elderly. The selection of appropriate interventions is crucial for the prevention and treatment of osteoporosis.
Modern acupuncturists have developed a unique Lingnan characteristic of fire-needling therapy by combining the climate of Lingnan and the physical characteristics of Lingnan people3. Fire needle therapy is a kind of treatment method in which special needles are burned red and quickly pierced into specific parts or acupoints of the human body to treat various ailments. This method is widely used in skin diseases, musculoskeletal and joint diseases, neurological diseases, and other systemic diseases and shows good efficacy4. The treatment of osteoporosis with fire needles has been used in clinics for a long time, and it has a better curative effect than simple acupuncture or oral administration of traditional Chinese medicine5,6,7. The Lingnan fire-needle therapy integrates acupuncture, three-edged needles, and scarring moxibustion. It can improve the qi and blood circulation in the meridians while warming the kidney. This treatment can address both blood stasis and kidney (Shen) deficiency, which contribute to the pathogenesis of OP in TCM. What's more, it has the advantages of being low cost, having quick effects, a short treatment period, and being safe. However, there is a lack of research on its mechanism. This paper introduces a specific procedure of Lingnan Fire-Needle in osteoporosis model rats and provides a methodological basis for conducting related basic research.
All experiments were carried out following the National Institutes of Health – Guide for the Care and Use of Laboratory Animals and were approved by the Hubei University of TCM – Institutional Animal Care and Use Committee. Adult female Sprague-Dawley (SD) rats, weighing 220 ± 20 g, were used for the test. All rats were maintained on a 12 h light/dark cycle at 23 ± 1 °C and 40%-50% humidity, with free access to food and water.
1. Pre-operative preparation
2. Acupuncture treatment
3. Post-acupuncture management
4. Data collection and analysis
The data in Table 1 shows that compared with the normal group, the thickness of trabecular bone (Tb.Th), the number of trabecular bone (Tb.N) and the static parameter bone volume fraction of trabecular bone (BV/TV) in the model group were all significantly reduced (p <0.05), and the separation of trabecular bone (Tb.Sp) was elevated (p <0.05); indicating that the bone structure of trabecular bone in trabecular bone-enriched areas of the femoral epiphysis of the rat was significantly disrupted after de-osteoporosis, indicating obvious damage.
Compared with the model group, the trabecular thickness, trabecular number, and trabecular static parameter bone volume fraction of the femur in the fire-acupuncture group were significantly increased (p <0.05), and trabecular separation was decreased (p <0.05). This suggested that fire needle therapy can improve the damage to cancellous bone structure of femur in osteoporosis model rats induced by bone removal.
Figure 4 shows the three-dimensional structure images of rat bone cancellous matrix in each group. Figure 4A is the normal group, Figure 4B is the model group and Figure 4C is the fire-needle group. As can be seen from the figure, compared with the normal group, a large number of trabeculae were lost in the center and even the periphery of the femur cancellous matrix in the model group, and a large number of cavities appeared in the lower part. The overall continuity of the bone structure was damaged, with the appearance of part of the free bone trabeculae. Compared with the model group, there was a large increase in thickness of trabeculae in the center and periphery of the cancellous bone of the femur in the fire-needle group, and the continuity of the overall bone structure was improved. This suggests that fire-needles can protect the trabecular structure of the cancellous bone of the femur in the rat model of ovariectomy-induced osteoporosis.
Figure 1: Rat fixation method: swing rats bound with coat. After dressing the rat in a rat coat, the rat is secured and suspended in the air by hooking the rat coat with two S-hooks. Please click here to view a larger version of this figure.
Figure 2: Lingnan Fire-Needle. (A) Needle tools. Choose a fine fire needle with a size of 0.40 mm x 13 mm. (B) Burning needles. Put the needle tip and needle body on the alcohol-soaked cotton balls and heat it. Please click here to view a larger version of this figure.
Figure 3: Fire needle acupuncture procedure at four acupoints. (A) Pishu (BL 20): Located between the ribs on the lower two sides of the 12th thoracic vertebra, 6 mm from the mid-dorsal line (B) Shenshu (BL 23): Located on the lower two sides of the second lumbar vertebra, 6 mm from the mid-dorsal line (C) Zusanli (ST 36): Located on the posterior and lateral side of the knee, about 3 mm below the small head of the fibula. (D) Sanyinjiao (SP 6): Located about 10 mm straight up from the tip of the inner ankle of the hind limb. Please click here to view a larger version of this figure.
Figure 4: Comparison of the three-dimensional structure of the cancellous bone of the distal femur of rats in various groups. (A) The normal group. (B) The model group. (C) The fire-needle group. Scale bars: 500 µm. Please click here to view a larger version of this figure.
Group | Tb.N(mm) | Tb.Sp(mm) | Tb.Th(mm) | BV/TV |
normal group | 3.29±0.47 | 0.23±0.06 | 0.12±0.03 | 0.39±0.14 |
model group | 0.96±0.78* | 0.66±0.44* | 0.09±0.01* | 0.17±0.11* |
fire-needle group | 2.73±0.76Δ | 0.33±0.20Δ | 0.12±0.02Δ | 0.33±0.16Δ |
Table 1: Fire needling effect on microstructural indices of femoral osteoporosis. Data shows mean ± SD, n= 10. For comparison performed with normal group, *p<0.05; For comparison performed with model group, Δp<0.05.
Lingnan fire-needle therapy has a profound historical background. Records on fire needles and needling methods can be traced back to Huangdi Neijing. Modern acupuncturists Situ Bell and Zhang Jiawei combined Lingnan's climate and the physical characteristics of its people to create Lingnan fire-needle therapy3. Lin Guohua summarized Lingnan Fire-Needle therapy, as warming, dredging, tonifying, clearing, and eliminating, with warming as the essence24.
The first step to using fire needles is selecting the appropriate type of needle. Fire needles can be categorized into three main categories: single-head, multi-head, and flat-head. The single-head fire needle is widely used in clinical practice and is commonly used for multi-system diseases. The multi-head fire needle combines three fine or three medium-coarse fire needles in a triangular shape, mainly used to treat skin diseases. The flat-head fire needle is commonly used to remove various kinds of moles, warts, and other excessive organisms on the skin25,26. The study selected single-head needles because they have a broader range of applications and more features, which makes it easier to obtain fine needles suitable for the size of rats.
Secondly, the proper use of fire-needle therapy requires critical criteria for cauterizing needles. Researchers27 have found that cauterizing needles to a specific temperature is necessary for their effectiveness. The stimulation may not alleviate the relevant pathological changes if the temperature is not high enough. Therefore, to achieve the desired therapeutic effect, the needles used in fire-needle therapy must be burned to a reddish or bright white color and then quickly inserted into the selected acupoints or parts. Furthermore, as the criteria for burning needles with fire needles vary depending on the fire-needling instruments, needling sites, and the diseases treated, we have compiled a comprehensive set of criteria for burning needles with fire needles that can be referenced in Table 2. In the present study, we used a single-head fire needle for multipoint stimulation instead of a multi-head fire needle. This was because multiple needles being too close together could not ensure that each needle would be cauterized uniformly.
Needle tools | Degree of needle burning | Indications |
Single-head Fire Needle | Reddish-red. | Bone and Joint Diseases and painful disease |
Multi-head Fire needle | The tip of the needle is slightly hot. | Skin diseases such as Acne |
Flat-head Fire Needle | Bright white. The handle of the needle is slightly hot. | Neoplasm such as filiform warts |
Table 2: The criteria for burning needles.
Regarding the angle of fire needle insertion, it is typically vertical. As for how deep to insert the needle, there are no established standards yet. However, it is generally suggested that deeper insertion is better for areas with more muscle and thicker skin, whereas shallower insertion is more appropriate for areas with thinner skin and muscles. Additionally, many experts in the field believe that the depth of fire needling should be like that of filiform needle needling28. A study suggests the depth of fire needles should be shallower than filiform needles when needling acupoints and slightly deeper than filiform needles when needling pain points22. As a result, regarding the actual application of fire needles, referring to the standard for filiform needles first and then determining the depth of needling based on clinical experience is advisable.
Based on the collective opinion of 192 experts in Lingnan, the primary cause of OP in high-risk groups is kidney (Shen) deficiency, which leads to secondary blood stasis. Therefore, the treatment for OP involves addressing both the kidney (Shen) deficiency and blood stasis simultaneously29. Currently, acupuncture is a widely used treatment for OP. The different types of acupuncture treatments include filiform needle therapy, moxibustion, warm acupuncture, electro-acupuncture (EA), thread-embedding therapy, acupoint injection, a combination of acupuncture and medicine, and a combination of acupuncture and moxibustion. Among these, the most used treatments in clinical practice are thread-embedding therapy, moxibustion, and a combination of acupuncture and medicine30. Clinically, fire-needle therapy is widely used for 137 different diseases targeting several organ systems, such as the motor system, nervous system, endocrine system, digestive system, obstetrics, and gynecology, among which the most applied are motor diseases31. The Lingnan fire-needle therapy is a treatment that combines the benefits of acupuncture, three-edged needles, and scarring moxibustion. It can improve qi and blood circulation in the meridians and warm the kidney (Shen). This treatment can address both blood stasis and kidney (Shen) deficiency, which contribute to the pathogenesis of OP in TCM. In addition, it has the advantages of being low cost, having quick effects, a short treatment period, and being safe. Clinical trials also show that combining fire-needle therapy and acupuncture treatment is more effective in treating OP than simple acupuncture or mediciation5,6. Joint pain is one of the typical symptoms of OP, and it has been confirmed that the efficacy of fire-needle therapy is significantly better than filiform needle therapy in the treatment of joint pain32.
Bone strength depends on bone density, the amount of bone per unit volume. The number and distribution of bone trabeculae, a component of bone mass, significantly influences bone volume and, consequently, bone density. Bone volume fraction indicates the percentage of bone volume per unit of tissue volume and is an essential reference for bone mass23. As part of the skeletal system, the cancellous bone's primary function is supporting and facilitating movement. However, increasing its size can reduce bone density, decreasing bone strength. The skeletal structure of cancellous bone is spongy and composed of trabeculae. Therefore, the structure of the cancellous bone is determined by the trabeculae. To maintain the strength of cancellous bone, it is crucial to ensure sufficient trabeculae are present as a framework. Secondly, it is necessary to keep a relatively adequate number of connections between the trabeculae to ensure the structural stability of bone33. For the trabeculae to be able to carry a certain amount of load, their thickness must be maintained. The structure of cancellous bone is evaluated based on the number of trabeculae present, their connectivity, and their thickness34. After comparing the structural parameters of cancellous bone (Table 1), our findings revealed significant differences between the model group of rats and the normal group. The number of trabeculae, trabecular thickness, and bone volume fraction of the femur were reduced, while trabecular separation was elevated in the model group. These findings suggest that the cancellous bone structure changes the model group, possibly leading to osteoporosis or other bone diseases. Based on the three-dimensional structural image of the cancellous bone, it was observed that the middle part lacked trabeculae, and more than half of the trabeculae in the upper part of the periphery were also missing. This indicates that the bone structure integrity of the femur in rats after ovariectomy had been compromised. Compared to the model group, the femur in the fire-needle group showed increased trabeculae, trabecular thickness, bone volume fraction, and decreased trabecular separation. Additionally, when the three-dimensional structural diagram of the cancellous bone was considered, it was observed that the central cavity of the fire-needle group was reduced, and the peripheral bone trabeculae were complete (Figure 4). This study demonstrates that fire-needle therapy effectively prevents and controls damage to the cancellous bone structure of the femur bone in rats that have undergone ovariectomy.
The limitations of the ovariectomy model rats selected for this study are as follows. Estrogen reduction is one of the risk factors for primary OP35. For this reason, ovariectomy surgery is a dependable method for establishing OP rat models8,9,10. Additionally, SD rats are not only easily accessible but also docile, with relaxed feeding conditions. Consequently, we initially examined this model and recommended using fine fire-needles to stimulate acupoints. Our long-term plan is to expand our research scope by further validating the effectiveness of fire-needling therapy in alleviating OP in other models, such as aging rats. Finally, Table 3 summarizes the efficacy of acupuncture alone on osteoporosis model rats and its mechanism of action. We intend to conduct a more in-depth investigation into the possible mechanisms in the coming future36,37,38,39,40,41,42.
Outcome indicator | Mechanism of action | Reference | ||||
bone resorption | Acupuncture prevents bone loss and structural changes by suppressing bone resorption. | 36 | ||||
bone strength | Acupuncture increased the trabecular bone volume and thickness, lowered the trabecular separation of tibiae and restricted the excretion of phosphorus and Dpd, while promoting the concentrations of serum osteocalcin. | 37 | ||||
bone metabolism | Acupuncture can significantly downregulate serum ALP, BGP and TRAP levels in OVX rats. | 38 | ||||
signaling pathway | Acupuncture improves bone mineral density, attenuates in vivo inflammatory response, and increases osteogenesis-influencing factor levels in rats by modulating the Wnt signaling pathway. | 39,40 | ||||
endocrine-modulating effect | Acupuncture modulated the serum levels of estradiol, corticotrophin releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosterone (CORT). | 41 | ||||
bodyweight | Acupuncture modulates changes in leptin levels to abrogate the body weight gain. | 36,41 | ||||
brain-derived neurotrophic factor | acupuncture can elevate BDNF and TrkB expression levels and accelerate the process of fracture healing after osteoporosis. | 42 |
Table 3: The effect of simple acupuncture on the efficacy of osteoporosis model rats.
The authors have nothing to disclose.
This work was supported with funds from the National Natural Science Foundation of China (NSFC) Nos. 82374564 (to YJD) and Nos. 82074566 (to YJD) and from Sun Guojie Inheritance Base for TCM Acupuncture-Moxibustion of World Federation of Acupuncture-Moxibustion Societies in Wuhan, China (World Federation of Acupuncture-Moxibustion Societies [2019] No. 26) to YJD and the National Famous TCM Inheritance Studio construction project of the National Administration of Traditional Chinese Medicine, China (the National Administration of Traditional Chinese Medicine [2022] No. 5) to YJD.
75% Alcohol | Shandong Lircon medicaltechnology co., ltd | Disinfection | |
95% Alcohol | Shandong Lircon medicaltechnology co., ltd | Burn needles | |
Adult female Sprague-Dawley (SD) rats | Liaoning Changsheng biotechnology co., Ltd. | SCXK 2020-0001 | Modeling of osteoporosis |
Deluxe thermostat heat mat | Zhenhua Instruments | For maintaining the body temperature of rats. | |
Diclofenac sodium injection | Shandong Province Jianmu Bio-pharmaceutical Co. | 150182913 | Antipyretic and analgesic |
Elevated fixation rack | Taizhou Shi Ai Scientific and Educational Instruments and Equipment Co. | Fix rats | |
Fire needles | Beijing Luoya Shanchuan Medical Equipment Co., Ltd. | 20190240 | A tool of needling |
Hemostatic forceps | Qingdao Schultz Biotechnology Co. | Fix rats | |
Liguter | Shanghai Machi Trading Co. | H5 | Ignite alcohol |
Lodophor disinfecting solution | Qingdao Hai's Hainuo Inovation Disinfection Technology Co., Ltd. | 2016-0604 | Disinfection |
Medical cotton ball | Jiangsu Misawa Medical Supplies Co., Ltd. | 20172142357 | Disinfection |
pentobarbital sodium | Beijing Jiehui Biotechnology Co. | P3761 | anesthesia |
Pet electric clipper | Fenghua Xikou Lubao Knives & Scissors Electrical Appliance Factory | Shave the hair of rats | |
Self-made rat coat | Fix rats | ||
Tweezers | Qingdao Schultz Biotechnology Co. | Pinch cotton balls |