An interesting study by Paulson & Shay (2013) confirms that Acupuncture activates the sympathetic nervous system during and after treatment.
Their single blinded randomised descriptive study showed that those who received acupuncture to the forearm muscles (on one side) after a bout of fatiguing wrist extension exercises measured a bilateral decrease in skin resistance and distal skin temperature. There was a significant difference in outcome measures when compared to sham acupuncture or no treatment. The fact that the changes were measured bilaterally suggests central control changes, probably at the level of the hypothalamus.
The acupuncture group also measured an increase in perfusion (blood flow) but on the side of treatment only, which the authors suggest is likely to be due to a local circulatory versus central/systemic control change.