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Study seeks to show how acupuncture really works

May 30, 2010
Courtesy of Nature Publishing Group 
and World Science staff

Sci­en­tists are pre­sent­ing a new the­o­ry on the mech­an­ism of acupunc­ture—a tra­di­tion­al Chin­ese heal­ing tech­nique that seems to work for some ail­ments, though West­ern re­search­ers don’t un­der­stand why.

East­ern prac­ti­tion­ers say ac­u­punc­ture works by chang­ing en­er­gy flows in the body. West­ern sci­en­tists tend not to buy this ac­count, ar­gu­ing that the pro­posed en­er­gy fields have nev­er been seen or meas­ured.

An ac­u­punc­ture nee­dle com­mon­ly used to­day. (Cred­it: Takumi Fu­jita )
Ac­u­punc­ture in­volves in­sert­ing thin nee­dles in­to the skin at se­lected points to treat a range of cond­itions. Sev­er­al stud­ies have shown that it works for cer­tain kinds of pain; a study last year found that ac­u­punc­ture beats con­ven­tion­al treat­ment for chron­ic low­er back pain.

The new stu­dy, pub­lished in the May 30 on­line is­sue of the jour­nal Na­ture Neu­ro­sci­ence, sug­gests that ac­u­punc­ture works by ac­ti­vat­ing pain-sup­press­ing re­cep­tors, or mol­e­cules, in the ar­ea of the body where the nee­dle is in­sert­ed.

In the re­search, Mai­ken Ned­er­gaard of the Uni­vers­ity of Roch­es­ter Med­i­cal Cen­ter in New York and col­leagues in­sert­ed fi­ne nee­dles in­to the mouse equiv­a­lent of a tra­di­tion­al ac­u­punc­ture point near the knee. The re­search­ers ro­tated these nee­dles in­ter­mit­tently as is prac­ticed by acupunc­tur­ists. 

This eased the pain re­ac­tions of mice with an in­flamed paw, the re­search­ers found. It al­so strongly boosted the lo­cal tis­sue con­centra­t­ion of a neu­ro­trans­mitter, or a mol­e­cule that trans­mits sig­nals through nerves, called aden­o­sine. 

Pain re­lief re­quired the pres­ence of a par­tic­u­lar re­cep­tor for aden­o­sine, the re­search team found. A re­cep­tor is a mo­lec­u­lar struc­ture on the sur­face of a cell that acts as a sort of gate­way for al­low­ing spe­cif­ic types of “mes­sen­ger” mol­e­cules to de­liv­er a sig­nal.

The re­cep­tor in ques­tion, called the aden­o­sine A1 re­cep­tor, is known to lie on pain-transmitting nerve fibers and to re­duce the ac­ti­vity of these fibers when ac­tivated, ac­cord­ing to Ned­er­gaard and col­leagues.

The team found that no pain re­lief or aden­o­sine eleva­t­ion was ob­served when the nee­dles were in­sert­ed in­to the ac­u­punc­ture point with­out rota­t­ion. They al­so not­ed that a drug that pro­longs the life­time of aden­o­sine in live tis­sue helped to pro­long the pain-eas­ing ef­fect of mouse ac­u­punc­ture. 

“Thus, med­ica­t­ions that in­ter­fere with A1 re­cep­tors or aden­o­sine me­tab­o­lism may im­prove the clin­i­cal ben­e­fit of ac­u­punc­ture,” the re­search­ers wrote.

* * *

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Scientists are presenting a new theory on the mechanism of acupuncture—a traditional Eastern healing technique that seems to work for some conditions, though Western researchers don’t understand why. Chinese practitioners say acupuncture works by changing energy flows in the body. Western scientists tend not to buy this account, arguing that the proposed energy fields have never been seen or measured. Acupuncture involves inserting thin needles into the skin at selected points to treat various ailments. Several studies have shown that it works for certain kinds of pain; a study last year found that acupuncture beats conventional pain treatment for chronic lower back pain. The new study, published in the May 30 online issue of the journal Nature Neuroscience, suggests that acupuncture works by activating pain-suppressing receptors, or molecules, in the area of the body where the needle is inserted. In the research, Maiken Nedergaard of the University of Rochester Medical Center in New York and colleagues inserted fine needles into the mouse equivalent of a traditional acupuncture point near the knee. The researchers rotated these needles intermittently as is practiced by acupuncturists. This alleviated the pain reactions of mice with an inflamed paw, the researchers found. It also strongly boosted the local tissue concentration of a neurotransmitter, or a molecule that transmits signals through nerves, called adenosine. Pain relief required the presence of a particular receptor for adenosine, the research team found. A receptor is a molecular structure on the surface of a cell that acts as a sort of gateway for allowing specific types of “messenger” molecules to deliver a signal. The receptor in question, called the adenosine A1 receptor, is known to lie on pain-transmitting nerve fibers and to reduce the activity of these fibers when activated, according to Nedergaard and colleagues. The team found that no pain relief or adenosine elevation was observed when the needles were inserted into the acupuncture point without rotation. They also noted that a drug that prolongs the lifetime of adenosine in live tissue helped to prolong the pain-attenuating effect of mouse acupuncture. “Thus, medications that interfere with A1 receptors or adenosine metabolism may improve the clinical benefit of acupuncture,” the researchers wrote.