One of the most controversial aspects of acupuncture therapy is whether or not puncturing a specific acupoint has a therapeutic effect superior to puncturing any other point on the skin (that is, any point which is not recognized as an acupoint). The anatomy and histology of acupoints has been extensively studied. They are found in the proximities of the peripheral nerves and their bifurcations, in the neuromuscular conections, in blood vessels, in ligaments and in tendinomuscular fascias, and in the suture lines of the bones of the skull. In the acupuoints of the face and the forehead it was found that the acupoints are placed over cutaneous terminal branches of the trigeminal nerve and between the muscular branches of the facial nerve.
Some of the effects of acupuncture physiologically characterized until the present date in SNC
Nowadays, the worldwide tendency regarding acupuncture research tries to find the physiological mechanisms that would be responsible of the effects observed with the stimulation of the acupoints. In this sense, a fundamental breakthrough was given between 1977 and 1980 when it was discovered that the analgesic effects of acupuncture could be blocked if naloxone, an opioid antagonist, was administered. This means that the analgesic effects of acupuncture took place when the anti-nociceptive pathways were activated, mediated by the release of endorphines. This neurologic pathways whose principal effectors are beta-encephalin and dinorphine, has been characterized up until being located in the gray periacueductal substance and the hipotalamus, which seem responsible for a central analgesic effect of acupuncture, one that is susceptible to being inhibited by naloxone. However, other analgesic mechanisms of acupuncture, strictly local, seem to involve a certain level of sympathetic blockage and are not inhibited by naloxone.
The clinical evidence indicates that acupuncture can have therapeutic effects in some cases of hypertension, coronary cardiac disease, arrhythmias ,angina de pecho and myocardiac stroke. Several authors have demonstrated that acupuncture diminishes arterial pressure, specially systolic pressure.
Mechanisms of the cardiovascular effects of acupuncture
The effects of acupuncture and electroacupuncture on the cardiovascular system are probably the result of the arousal of the group III and possibly group IV of the afferent fibres that underlie in the acupuncture point (Li et al, 1998; Liu et al, 1986). It is well known that the ventrolateral rostral marrow (VLrM) is an important area of the cardiovascular center. The neurones of this area recieve information from the hipothalamus and the middle brain, other cardiovascular centres and some afferent impulses from barorreceptors, chimiorreceptors, cardiopulmonar receptors, psomatic and esplechnic nerves, besides from other acupuncture points; at the same time the VLrM sends descending information to the sympathetic preganglionar neurones in the intermediolateral marrow of the spinal cord. The VLrM marrow integrates a lot of cardiovascular regulating information; in this way, the neurones of the VLrM are considered important in the sympathetic tone control and the cardiovascular activity.
