What is acupuncture
Acupuncture is a form of alternative medicine by which needles are pierced through the skin and helps to treat diseases.
Science behind acupuncture
So far, the research on acupuncture has shown that acupuncture can help to suppress pain but probably will not treat diseases.
Really, it all has to do with connective tissue. Connective tissue is tissue that connects, supports, binds, or separates other tissues or organs. In the connective tissue, there are cells known fibroblasts. According to an article in The Scientist (http://www.the-scientist.com/?articles.view/articleNo/35301/title/The-Science-of-Stretch/):
the cells that are responsible for synthesizing all the proteins that make up the extracellular matrix. These cells reside within the matrix they create, responding to mechanical stimulation by regulating the amount of collagen and other matrix proteins produced, and by secreting matrix-degrading enzymes in response to chronic changes in tissue forces.
Their research also showed that:
the fibroblasts initiated a specific Rho-dependent cytoskeletal reorganization that was required for the tissue to fully relax. Rho is an intracellular signaling molecule known to play a role in cell motility and the remodeling of cell-surface proteins that connect the fibroblast to its surrounding matrix.
They also mentioned that the fibroblasts secrete ATP, which is converted to adenosine which is an analgesic. This leads me to a second article in in Discover Magazine (http://blogs.discovermagazine.com/notrocketscience/2010/05/30/a-biological-basis-for-acupuncture-or-more-evidence-for-a-placebo-effect/#.VjAmFyPn_qD). In this article, they mention about a paper that described the importance of adenosine.
The research showed that the A1 receptor for adenosine is important for acupuncture to work. But they mention in the Discover article that there is nothing special about acupuncture. They say:
o answer that, clinical trials have used sophisticated methods, including “sham needles”, where the needle’s point retracts back into the shaft like the blade of a movie knife. It never breaks the skin, but patients can’t tell the difference from a real, penetrating needle. Last year, one such trial (which was widely misreported) found that acupuncture does help to relieve chronic back pain and outperformed “usual care”. However, it didn’t matter whether the needles actually pierce the skin, because sham needles were just as effective. Nor did it matter where the needles were placed, contrary to what acupuncturists would have us believe.
It is hard to also have a control but it seems the best may be the sham needles. However, much of this research is debatrd.
I hope I have answered your question. Please ask anything more in the comments.