Background. Although irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with an absence of demonstrable pathology, it is associated with significant impairment of quality of life and causes a heavy burden on the health care system. As conventional IBS treatments are far from satisfactory, people turn to Complementary and Alternative Medicine (CAM). One of the most acceptable CAM treatments is acupuncture, which has been considered to be effective in alleviating abdominal bloating, increasing rectal pain threshold, and improving the general well being of IBS patients. However, the underlying mechanisms of these therapeutic effects remain unknown. This study is an investigation of the therapeutic mechanisms of acupuncture treatment of IBS. / Conclusion. Acupuncture attenuates visceral hyperalgesia by inhibiting 5-HT and c-Fos activity in the brain-gut axis. This observation may shed light on possible mechanisms by which acupuncture alleviates symptoms of IBS. / Study 1. A Neonatal Maternal Separation Stress Model (NMSS) was tested. Our results showed that this model was a reliable and stable model for IBS animal study and that visceral hyperalgesia was associated with increased serotonin (5-HT) and c-Fos activity of the brain-gut axis. / Study 2. Two methods were used to test visceral hyperalgesia in response to colorectal distension (CRD), namely Abdominal Withdrawal Response (AWR) and Electromyogram (EMG). There methods were compared for their effectiveness in measuring visceromotor response (VMR) in a NMSS rat model. Our results showed that EMG is the more reliable tool for evaluating VMR to CRD in NMSS rats. / Study 3. There were three parts to this study. First, we reviewed the TCM literature on the use of acupuncture in IBS and concluded that the two most commonly used acupoints for this condition are ST-36 and CV-12 and that, of the two, ST-36 may be the more appropriate acupoint for treatment. Second, we tested invasive and non-invasive sham acupuncture (placebo) and found that neither produces any therapeutic effect when compared to real electroacupuncture. Third, we used the NMSS rat as the animal model, ST-36 as the treatment acupoint, non-invasive sham acupuncture as the placebo, and EMG as the tool to evaluate VMR in response to CRD alter acupuncture intervention. Our results showed that acupuncture not only attenuated 5-HT and c-Fos activity but also reduced visceral hyperalgesia in the NMSS rat. / Ziea, Tat Chi. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3423. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 122-141). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.