Regulatory Role of Orexin in the Antistress Effect of "Press Tack Needle" Acupuncture Treatment.

The aim of this research was to investigate the antistress effect of press tack needle (PTN) acupuncture treatment using rats with social isolation stress (SIS). Rats were divided into non-stress group (Grouped+sham), stress group (SIS+sham), and PTN-treated SIS group (SIS+PTN). Rats in the SIS+PTN and SIS+sham groups were housed alone for eight days. For the SIS+PTN group, a PTN (length, 0.3 or 1.2 mm) was fixed on the GV20 acupoint on day 7. We measured stress behavior based on the time the rats showed aggressive behavior and the levels of plasma corticosterone and orexin A on day 8. In addition, the orexin-1 receptor or orexin-2 receptor antagonist was administered to rats that were exposed to SIS. The duration of aggressive behavior was significantly prolonged in the SIS+sham group, and the prolonged duration was inhibited in the SIS+PTN (1.2 mm) group. The levels of plasma corticosterone and orexin A were significantly increased in the SIS+sham group; however, these increases were inhibited in the SIS+PTN group. The aggressive behavior was significantly reduced after the orexin-2 receptor antagonist was administered. These findings suggest that PTN treatment at GV20 may have an antistress effect, and the control of orexin is a mechanism underlying this phenomenon.