Acupuncture is the process of stimulating acupoints by inserting thin metal needles and manipulating them with manual, electrical, or other forms of stimulation. Acupoints are located throughout the body, with the majority located along 12 bilateral meridians and two midline channels, namely the Du and Ren Meridians.
Acupuncture points (Acupoints) are neurologically dynamic and have three phases, latent, passive and active. In healthy individuals (state of homeostasis) acupoints are neither tender nor sensitive, these are latent acupoints. Under the influence of pathophysiological disturbances such as chronic pain, inflammation; these latent acupuncture points become either active or passive points. Active acupuncture points continuously fire impulses to the brain even without external mechanical pressure and may sensitize (more responsive) the neurons of the spinal cord and brain, these acupoints will reduce electrical signals to the brain after acupuncture needling. On the other hand, passive acupoints do not send continuous impulses to the brain and only become tender when pressure is applied. These points will increase electrical signal to the brain.
When an acupuncture needle penetrates the skin and reaches the acupoint, it traverses several layers, including the epidermis, dermis, subcutaneous tissue, and muscle septa. All of the Acupuncture points are located in the connected tissue in various depths. Connective tissues play critical roles in cellular and mechanical signaling pathways, and are generally considered the material basis for the therapeutic effects of acupuncture. The connective tissues into five categories: dense connective tissue in the dermis, loose connective tissue in the subcutaneous layer, loose connective tissue in muscle septa, connective tissue surrounding neurovascular bundles, and connective tissue in organ hilums and capsules. Among these, the latter four types are loose connective tissues and are the primary sites for mechanical coupling processes during acupuncture.
The mechanical stimulation induced by acupuncture causes collagen fibers in loose connective tissue to wrap around the needle, thereby changing the tension within the extracellular matrix. These subtle mechanical changes circulate through the fibrous network in the form of “vibrations” or elastic waves, with a transmission speed three times faster than that of neural signals. To adapt to tension changes caused by tissue stretching, fibroblasts (cells responsible for structure and repair of the connective tissue) in connective tissue rapidly remodel their cytoskeleton to regulate tissue tension and release mediators such as adenosine (important for local pain suppression), anti-inflammatory cytokines via mast cell activation, release of growth factor and neoangiogenesis (new blood vessel formation). This process triggers a cascade of physiological and biomechanical responses, such as changes in local blood circulation, tissue relaxation, and contraction. Moreover, acupuncture may exert extensive effects at the cellular level, including the regulation of cellular metabolism and signaling pathways.
Acupuncture has shown significant efficacy in promoting mitochondrial function recovery and reducing mitochondrial degradation. Studies have demonstrated that acupuncture can rapidly restore the structure and quantity of damaged mitochondria, promote mitochondrial biosynthesis, and accelerate mitochondrial renewal, thereby improving cellular energy metabolism, making Acupuncture an effective treatment for diseases related to mitochondrial dysfunction such as depression and headaches.
