Effects of pertussis toxin on electroacupuncture-produced anti-hyperalgesia in inflamed rats

Nerve Stimulation: Immunomodulation and Control of Inflammation

Neuronal stimulation is an emerging field in modern medicine to control organ function and re-establish physiological homeostasis during illness. Transdermal nerve stimulation with electroacupuncture is currently endorsed by the World Health Organization (WHO) and the National Institutes of Health (NIH), and is used by millions of people to control pain and inflammation. Recent advances in electroacupuncture may permit activation of specific neuronal networks to prevent organ damage in inflammatory and infectious disorders. Experimental studies of nerve stimulation are also providing new information on the functional organization of the nervous system to control inflammation and its clinical implications in infectious and inflammatory disorders. These studies may allow the design of novel non-invasive techniques for nerve stimulation to help to control immune and organ functions.

Mechanisms of acupuncture-electroacupuncture on persistent pain

In the last decade, preclinical investigations of electroacupuncture mechanisms on persistent tissue injury (inflammatory), nerve injury (neuropathic), cancer, and visceral pain have increased. These studies show that electroacupuncture activates the nervous system differently in health than in pain conditions, alleviates both sensory and affective inflammatory pain, and inhibits inflammatory and neuropathic pain more effectively at 2 to 10 Hz than at 100 Hz. Electroacupuncture blocks pain by activating a variety of bioactive chemicals through peripheral, spinal, and supraspinal mechanisms. These include opioids, which desensitize peripheral nociceptors and reduce proinflammatory cytokines peripherally and in the spinal cord, and serotonin and norepinephrine, which decrease spinal N-methyl-D-aspartate receptor subunit GluN1 phosphorylation. Additional studies suggest that electroacupuncture, when combined with low dosages of conventional analgesics, provides effective pain management which can forestall the side effects of often-debilitating pharmaceuticals.

The status and future of acupuncture mechanism research

On November 8-9, 2007, the Society for Acupuncture Research (SAR) hosted an international conference to mark the tenth anniversary of the landmark NIH [National Institutes of Health] Consensus Development Conference on Acupuncture. More than 300 acupuncture researchers, practitioners, students, funding agency personnel, and health policy analysts from 20 countries attended the SAR meeting held at the University of Maryland School of Medicine, Baltimore, MD. This paper summarizes important invited lectures in the area of basic and translational acupuncture research. Specific areas include the scientific assessment of acupuncture points and meridians, the neural mechanisms of cardiovascular regulation by acupuncture, mechanisms for electroacupuncture applied to persistent inflammation and pain, basic and translational research on acupuncture in gynecologic applications, the application of functional neuroimaging to acupuncture research with specific application to carpal-tunnel syndrome and fibromyalgia, and the association of the connective tissue system to acupuncture research. In summary, mechanistic models for acupuncture effects that have been investigated experimentally have focused on the effects of acupuncture needle stimulation on the nervous system, muscles, and connective tissue. These mechanistic models are not mutually exclusive. Iterative testing, expanding, and perhaps merging of such models will potentially lead to an incremental understanding of the effects of manual and electrical stimulation of acupuncture needles that is solidly rooted in physiology.

Neural mechanism underlying acupuncture analgesia

Acupuncture has been accepted to effectively treat chronic pain by inserting needles into the specific "acupuncture points" (acupoints) on the patient's body. During the last decades, our understanding of how the brain processes acupuncture analgesia has undergone considerable development. Acupuncture analgesia is manifested only when the intricate feeling (soreness, numbness, heaviness and distension) of acupuncture in patients occurs following acupuncture manipulation. Manual acupuncture (MA) is the insertion of an acupuncture needle into acupoint followed by the twisting of the needle up and down by hand. In MA, all types of afferent fibers (Abeta, Adelta and C) are activated. In electrical acupuncture (EA), a stimulating current via the inserted needle is delivered to acupoints. Electrical current intense enough to excite Abeta- and part of Adelta-fibers can induce an analgesic effect. Acupuncture signals ascend mainly through the spinal ventrolateral funiculus to the brain. Many brain nuclei composing a complicated network are involved in processing acupuncture analgesia, including the nucleus raphe magnus (NRM), periaqueductal grey (PAG), locus coeruleus, arcuate nucleus (Arc), preoptic area, nucleus submedius, habenular nucleus, accumbens nucleus, caudate nucleus, septal area, amygdale, etc. Acupuncture analgesia is essentially a manifestation of integrative processes at different levels in the CNS between afferent impulses from pain regions and impulses from acupoints. In the last decade, profound studies on neural mechanisms underlying acupuncture analgesia predominately focus on cellular and molecular substrate and functional brain imaging and have developed rapidly. Diverse signal molecules contribute to mediating acupuncture analgesia, such as opioid peptides (mu-, delta- and kappa-receptors), glutamate (NMDA and AMPA/KA receptors), 5-hydroxytryptamine, and cholecystokinin octapeptide. Among these, the opioid peptides and their receptors in Arc-PAG-NRM-spinal dorsal horn pathway play a pivotal role in mediating acupuncture analgesia. The release of opioid peptides evoked by electroacupuncture is frequency-dependent. EA at 2 and 100Hz produces release of enkephalin and dynorphin in the spinal cord, respectively. CCK-8 antagonizes acupuncture analgesia. The individual differences of acupuncture analgesia are associated with inherited genetic factors and the density of CCK receptors. The brain regions associated with acupuncture analgesia identified in animal experiments were confirmed and further explored in the human brain by means of functional imaging. EA analgesia is likely associated with its counter-regulation to spinal glial activation. PTX-sesntive Gi/o protein- and MAP kinase-mediated signal pathways as well as the downstream events NF-kappaB, c-fos and c-jun play important roles in EA analgesia.