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junctions where the Golgi tendon organs are located. For example, BL-57 is located at the junction between the gastrocnemius muscle and the calcanean tendon.
The anatomic nature of acupuncture points represents neural vascular bundles, containing
· Abundant of free nerve endings
· Small arterioles, veins
· Lymphatics
· Increased concentration of mast cells
· Contain higher conductance, lower impedance, and higher capacitance than adjacent tissues
· Close proximity to somatic afferent terminals, suggesting the likelihood of interaction and modulation of afferent signals by needle placement
· Most are also found in palpable depressions
D. Pain Control Mechanism of Acupuncture
Many of the systematic reviews supporting acupuncture efficacy are for painful conditions. There are a few mechanisms by which acupuncture affects analgesia. These mechanisms have been extensively investigated and are quite well understood, and are enhanced with the passage of small amounts of electrical current through the acupuncture needle (electroacupuncture). These mechanisms are (Melzack R. 1965):
a) Local Effects
enkephalin to activate the raphe descending system, which then inhibit pain transmission within spinal cord.
· The pituitary releases beta-endorphin into the blood and cerebral spinal fluid to cause analgesia at a distance.
· The hypothalamus uses beta-endorphin to activate the descending analgesia system.
d) Gate Theory
· Acupuncture activates the Aβfibers (larger and fast conducting nerve fibers than C-fiber). These fibers lead to inhibition (pre-synaptic) of information carried by the C fibers (pain), so that the C fibers could no longer travel to the CNS to cause pain to the body
e) Acupuncture on fMRI Function
· Acupoints that have analgesic properties associated with them tend to activate specific pain-associated brainstem regions. Non-analgesic acupuncture points do not activate these regions; rather they activate other regions of the brain. (Chiu JH. 2003)
f) Frequency of Electroacupuncture
· Low frequency (2-40 Hz) predominantly stimulates A-delta fibers and induces the release of beta- endorphin, met-enkephalin and endomorphin from the brainstem predominately.
· High frequency (100 Hz) predominantly stimulates C fibers and selectively increases the release of dynorphin predominantly.
· Higher frequencies (200Hz), predominantly stimulates serotonergic fibers and releases serotonin and epinephrine. (Fwk S.1994)
· A combination of the two frequencies (2 and 100 Hz) produces a simultaneous release of all four opioid peptides, resulting in a maximal therapeutic effect. This finding has been verified in clinical studies in patients with various kinds of chronic pain including low back pain and diabetic neuropathic pain. (Han JS. 2004)
· One review showed 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 2–10 Hz than at 100 Hz. (Zhang R. 2014)
F. Conclusion
In the past 30 years there has been increasing evidence to support the use of acupuncture as a therapeutic modality in veterinary medicine. There has been extensive research proving its analgesic effects, therefore it is the primary clinical indication for its use in both human medicine and veterinary medicine.
Due to the intrinsic nature of the anatomical structures associated with the location of acupuncture points there are numerous systemic, local, and endocrine effects. For that reason, there are a variety of valuable clinical indications from pain management to cognition improvement and others. As more research develops in the upcoming years it is likely that acupuncture will become mainstream and a treatment modality taught in veterinary schools across the country.
· A form of counter-irritation effect
· Insertion of needle in an acupoint results in local tissue
damage (called microtrauma), which activates Hage- man’s tissue factor XII. This in turn results in the activa- tion of local coagulation cascade and the complement cascade, leading to the production of plasminogen, protein kinins, and prostaglandins.
· The microtrauma also causes mast cell degranulation, which releases histamine, heparin, proteases and bra- dykinin.
· These local reactions ultimately result in increase blood flow to the area and local immune responsiveness, that help relieve pain and reduce inflammation and edema.
· Connective tissues are stretched when needles are placed in acupoints rather, which relax the muscles and tissues in the local area.
b) Spinal Cord Effects
· When nerve impulses travel up the sensory nerves, it activates three centers (spinal cord, midbrain, and hypothalamus/pituitary) to produce analgesic effects.
· At the spinal site, enkephalin and dynorphin are used to block incoming pain messages.
· Electroacupuncture at 2 Hz and 100 Hz cause the release of enkephalin and dynorphin in the spinal cord, respectively.
c) Brainstem Effects
· The neuronal network that serves acupuncture analgesia is thought to activate structures of the descending inhibitory pathways and deactivate limbic structures within the ascending nociceptive pathway.
· The midbrain uses endorphin to activate periaqueductal gray, and use serotonin and
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