This may seem a bit off-track, but animal studies in acupuncture are interesting because they rule out the placebo effect (feeling better due to simple suggestion or expectation). From the Guardian:
Ever since Chinese doctors first poked their patients with sharp objects 4,000 years ago, and charged them for the pleasure, acupuncture has been shrouded in mystery.
Tradition has it that the procedure works by improving the flow of āqiā along invisible energy channels called meridians, but research published today points to a less mystical explanation for the painkilling claims of acupuncture.
The answer, according to a team of scientists in New York, follows an extraordinary study in which researchers gave regular acupuncture sessions to mice with sore paws.
After each half-hour session the mice felt less discomfort in their paws because the needles triggered the release of a natural painkiller, the researchers say. The needles caused tissue damage that stimulated cells to produce adenosine, an anti-inflammatory chemical, that was effective for up to an hour after the therapy was over.