Effect of Acupuncture on Neurotransmitters/Modulators

Abstract

Acupuncture research, especially the mechanistic investigations on acupuncture analgesia, has yielded abundant information showing that acupuncture signal, either generated by manual acupuncture or electroacupuncture (Ea), remarkably influences the release, synthesis, reuptake, and degradation of the central neurotransmitters/modulators, including monoamines (e.g., serotonin, noradrenalin, and dopamine), acetylcholine (ACh), amino acids, orphanin FQ, substance P, prostaglandin, cholecystokinin-octopeptide-8 (CCK-8), somatostatin, and neurotrophic factors. In general, acupuncture enhances the activity of the endogenous opioid peptides, serotonin, dopamine, ACh, and inhibitory amino acids such as γ-aminobutyric acid (GABa), glycine, taurine, and lactamine, while it attenuates the activity of noradrenalin and excitatory amino acids including glutamate and aspartic acid. A prolonged period of acupuncture may induce excessive production of CCK-8 and deplete some pro-acupuncture substances, thus causing the so-called acupuncture tolerance. Acupuncture also regulates the expression and function of the corresponding receptors. However, the effects of acupuncture on the central neurotransmitters/modulators are dependent on the status of the organism and conditions of acupuncture (e.g., stimulation parameters and acupoints), and vary from region to region in the central nervous system. Although these data were largely obtained from the studies on acupuncture analgesia, it is reasonable to presume that acupuncture is capable of modulating the brain functions through the regulation of central neurotransmitters/modu-lators, because all the acupuncture-influenced neurotransmitters/modulators participate directly or indirectly in neural regulation in almost all aspects.