behavioral measurement in tuina-intervened rats

Assessing Tuina Therapy's Pain Relief in Chronic Constriction Rats

Peripheral neuropathic pain (pNP) refers to pain caused by a lesion or disease of the peripheral somatosensory nervous system, manifested as a series of symptoms and signs, with hyperalgesia as one of the main symptoms1,2. Hyperalgesia is a heightened experience of pain caused by a noxious stimulus, including pinprick, cold, and heat3. Large epidemiological studies have been conducted, which show pNP is the most common, with a prevalence rate of 6.9%-10% in neuropathic pain4. pNP can be caused by multiple diseases, including injury of the nerve, postherpetic neuralgia, painful diabetic polyneuropathy, multiple sclerosis, stroke, cancer, etc.5. Nowadays, the main method for treating pNP is medication, but the effect is not ideal; and the side effects are significant, which is the main reason for the high economic burden on individuals and society6.
Tuina is a green, economical, safe, and effective external treatment method of traditional Chinese medicine7. Many clinical studies have proven the analgesic effect of tuina on pNP, and basic studies have verified the immediate and cumulative analgesic effects of tuina8,9. The main cumulative analgesic mechanism of tuina is to reduce the levels of inflammatory factors and inhibit the activation of glial cells10,11. The previous research confirmed the cumulative analgesic effect of tuina and found differentially expressed genes (DEGs) in the dorsal root ganglia (DRG) and spinal dorsal horn (SDH) of rats with sciatic nerve injury after 20 times of tuina treatment, mainly related to protein binding, pressure response, and neuronal projection12. In recent studies, it has been confirmed that tuina has an immediate analgesic effect and that 1-time tuina intervention could alleviate the hyperalgesia of minor CCI rats and especially ease thermal hyperalgesia more effectively13. However, the optimal time point for the analgesic effect of tuina may vary depending on the injury sensation (cold, heat, mechanical), affecting the exploration of the initiation mechanism of tuina analgesia.
Inflammatory mediators can sensitize and activate pain receptors, leading to decreased discharge thresholds and ectopic discharges, thereby contributing to peripheral sensitization14,15. After peripheral nerve injury, TNF-&#945; is an initiator of the inflammatory response, which can promote the synthesis of inflammatory factors such as IL-10 and IL-1&#946;, causing direct tissue inflammatory injury, stimulating local nerve endings, and causing pain16,17,18. Tuina can achieve analgesic effects by reducing the expression of inflammatory factors such as TNF-&#945;, IL-10, IL-6, and IL-1&#946;19,20,21. The study selected minor CCI model rats to simulate clinical pNP and selected different time points for behavioral testing of cold, thermal, and mechanical stimulation pain after a 1-time tuina intervention by cold sensitivity threshold (CST), mechanical withdrawal threshold (MWT), thermal withdrawal latency (TWL), and choose IL-10 and TNF-&#945; in the serum by enzyme-linked immunosorbent assay (ELISA), in order to select the time point at which the analgesic effect of tuina is significant, providing a basis for the study of the initiation mechanism of tuina analgesia in the later stage.

Author Spotlight: Exploring the Initiation Mechanism of 'Three-Method and Three-Acupoint' Tuina Analgesia in Rats with Nerve Injury

Characteristics of Pain Changes in Rats with Nerve Injury Within 24 hours After One-Time Tuina Intervention

Our research scope belonged to the efficacy verification and the mechanism exploration of tuina therapy for neuropathic pain. We want to answer the effectiveness of tuina through animal experiments, providing scientific evidence for the analgesic efficacy of tuina in clinical practice. At present, RNA sequencing, calcium imaging, and the molecular biology technologies are used to promote further research in this field.The analgesic efficacy of tuina, within 24 hours after intervention, is significantly different at different time points. This provides a scientific basis for selecting appropriate behavioral time points and sampling for further molecular mechanism exploration in the later study of the initiation mechanism of the Three-Method and Three-Acupoint"tuina analgesia. The research protocol further validates the immediate and sustained analgesic effects of Three-Method and Three-Acupoint"tuina technique and provide a more accurate time point for exploring the initiation mechanism of tuina analgesia in the later stage.In subsequent research, we will continue to focus on exploring the initiation mechanism of analgesia by tuina in order to provide scientific evidence for clinical tuina treatment of neuropathic pain-related diseases.

Behavioral Measurement in Tuina-Intervened Rats

To begin, place the TuiNa intervened rat on an intelligent cold and hot plate pain detector with a surface temperature of four degrees Celsius. Cover the rat with a transparent plastic cage. Once the rat is acclimatized to the plastic cage, record the number of foot lifts in the operative side of the hind limb for the next five minutes.Place the rat on a grid surface in a test box for 15 to 30 minutes before testing. Move the probe of the pain to the center of the right posterior plantar region of the rat, and linearly increase the pressure by hand. When the rat lifts or licks its feet, record the threshold displayed on the instrument screen.Adapt the rat in a glass-bottom test box for 15 minutes before starting the test. On a thermal stimulation pain instrument, click on set and direction buttons to set the cutoff time to 30 seconds, and intensity to 50%Then click on start. Position the infrared probe to the center of the right posterior plantar region of the rat.When the rat lifts or licks its feet, record the latency of the foot retraction reflex. In cold sensitivity threshold analysis, compared to the model group, the Tuina group showed a significant reduction in foot lifts six hours post-treatment. The model group exhibited a significant increase in foot lifts compared to the sham group, highlighting the effect of the model intervention.The mechanical withdrawal threshold of each subgroup of Tuina was significantly higher than that of the model group. Except for 18 hours after Tuina, the model group had a significantly lower mechanical withdrawal threshold than the sham operation group. Thermal withdrawal latency analysis revealed a significant increase immediately, six hours, and 18 hours after Tuina in comparison to the model group.The model group showed a significant decrease compared to the sham operation group.

Research

JoVE Journal

Neuroscience

Tuina, as an external treatment method of traditional Chinese medicine, has been proven to have an analgesic effect on peripheral neuropathic pain (pNP) ...