About a third of human patients with digestive disorders “follow their gut” and seek help from complementary and alternative medicine (CAM) approaches designed to restore normal motility and glandular function.1 People may feel queasy about the risks of side effects from laxatives, enemas and psychoactive medications, whether they themselves or their animal companions are suffering from gastrointestinal (GI) complaints.2 Even when certain patients still require medications, their systems’ response to pharmacotherapy may prove inadequate. Introducing acupuncture and massage as neuromodulatory techniques can speed recovery and reduce reliance on drugs. Effective neuromodulation requires an understanding of the neural pathways involved and the means by which the one can restore normal firing patterns in the nervous system. When they design a neuromodulatory treatment, medical acupuncturists and massage therapists target body regions that send signals through peripheral nerves, spinal reflex pathways and brainstem nuclei. 3 An additional consideration in digestive disorders includes focus on the enteric nervous system (ENS). The ENS comprises a network of nearly 100 million neurons embedded within the walls of the alimentary canal. This impressive population of nerves can operate independently of the brain and spinal cord so that, in the absence of central nervous system (CNS) input, programs stored within the ENS can carry on intestinal motion.4 When things go awry, this “brain in the gut” can suffer a sort of “mental illness.”5 Exogenous stimulation from food-based antigens, toxins and invading microbes sensitize the gut. This promotes mast cells’ degranulation and release of pro-inflammatory mediators that alter ENS activity. The patient experiences abdominal pain and loose stools. From a protective standpoint, this inborn defense system flushes out offending organisms and ingested antigens through copious secretion of water, electrolytes and mucus conjoined with forceful and rapid propulsive motility. However, chronic stress can also activate mast cells, producing an uncomfortable and persistent syndrome of diarrhea, cramping and sensitivity to distension that becomes maladaptive instead of defensive.6 Called irritable bowel syndrome in humans, this disease state is receptive to neuromodulation through electroacupuncture (EA).7 Researchers hypothesize that EA inhibits mucosal mast cell activity and proliferation, thereby reducing abnormal secretion of cytokines. Furthermore, acupuncture counters neurogenic inflammation and pain associated with colonic inflammatory states, in part through cholinergic and endogenous opioid pathways.8-9-10 Massage induces neuromodulation as well and thereby slows abnormally rapid intestinal transit. In a clinical trial of massage for orphaned Ecuadoran infants, they recovered from diarrhea sooner than those in the control group. The mechanisms of medical massage parallel acupuncture in this case by modulating vagal nerve function. Laser therapy in conjunction with acupuncture also reduced diarrhea in infants.11 As research in neurogastroenterology progresses, conditions formerly regarded as “idiopathic” or “functional” are being re-contextualized as ENS neuropathology states. A recent investigation of the role of ENS abnormalities in dogs with idiopathic and secondary acquired megacolon suggested that depletion of a major neurotransmitter, vasoactive intestinal polypeptide (VIP), may precipitate constipation.12 In non-diseased individuals, VIP-containing nerve fibers support normal peristalsis from oral to aboral intestinal segments. Enteric neurons depleted of VIP may affect transit and smooth muscle relaxation, colonic tone, intestinal secretion and other functions. Progressive neuropathy of the ENS can lead to chronic intestinal pseudoobstruction, i.e., a pathophysiological state with symptoms mimicking a mechanical obstruction.13 EA helps to restore motor activity in the canine GI tract.14, 15 In addition to altering acid secretion and promoting gastric emptying, acupuncture approaches normalize motility.16 Somatic afferent stimulation from the point Tsusanli (ST36) in the cranial tibialis muscle sends input through the peroneal nerve in the hindlimb into the lumbosacral spinal cord, and up to the nucleus tractus solitarius in the brainstem where it influences vagal nerve output.17 In contrast, spinal cord reflexes integrate somatic input from truncal acupuncture point stimulation with afferent and efferent visceral pathways leading to the gut, modulating intestinal motility via sympathoexcitatory pathways.18 As noted earlier, massage similarly affects GI function through vagal and spinal cord reflexes. Abdominal massage in patients with spinal cord injury reduced abdominal distention and fecal incontinence while improving defecation frequency.19 Moderate pressure massage in preterm infants consistently elicited improvements in vagal activity, gastric motility, and weight gain.20 Massage of the abdomen in people with constipation produced cost-effective benefits over the long term, decreasing the severity of GI complaints and improving health-related quality of life.21 At the level of the stomach and esophagus, somatic afferent input generated by transcutaneous electrical nerve stimulation (TENS) significantly improved gastroparesis and allowed gastric emptying in critically ill human patients as compared to standard pro-motility drugs.22 Another study showed that acupuncture, performed on patients with gastroesophageal reflux disorder failing standard-dose proton pump inhibitor (PPI) therapy, was more efficacious than adding a second PPI drug in order to control residual heartburn and acid regurgitation.23 Both of these studies involved stimulation of a point on the antebrachium called “Neiguan” or PC6. Experimental animal studies indicate that PC6 stimulates somatic afferent pathways in the median nerve in the antebrachium to modulate autonomic nervous system integration at the level of the brainstem.24 Considering the evidence of benefit and low risk of injury from acupuncture and massage, these neuromodulatory techniques can confidently be recommended as abjunctive care for dogs and cats with GI dysfunction. Dr. Narda Robinson, DVM, DO, Dipl. ABMA, FAAMA, oversees complementary veterinary education at Colorado State University. FOOTNOTES 1. Van Tilburg MAL, Palsson OS, Levy RL, et al. Complementary and alternative medicine use and cost in functional bowel disorders: a six month prospective study in a large HMO. BMC Complementary and Alternative Medicine. 2008;8:46. 2. Lin L-W, Fu Y-T, Dunning T, et al. Efficacy of Traditional Chinese Medicine for the management of constipation: a systematic review. J Alt Comp Med. 2009;15(12):1335-1346.. 3. Cabioglu MT and Surucu HS. Acupuncture and neurophysiology. Medical Acupuncture. 2009;21(1):13-20. 4. Wood JD. Enteric neuroimmunophysiology and pathophysiology. Gastroenterology. 2004;127:635-637. 5. Hadhazy A. Think twice: how the gut’s “second brain” influences mood and well-being. Scientific American. February 12, 2010. Obtained at http://www.scientificamerican.com/article.cfm?id=gut-second-brain&print=true on 12-19-10. 6. Wood JD. Enteric neuroimmunophysiology and pathophysiology. Gastroenterology. 2004;127:635-637. 7. Wu H-G, Jiang B, Zhou E-H, et al. Regulatory mechanism of electroacupuncture in irritable bowel syndrome: preventing MC activation and decreasing SP VIP secretion. Dig Dis Sci. 2008;53:1644-1651. 8. Kim H-Y, Hahm D-H, Sohn B-Y, et al. Skin on GV01 acupoint in colonic inflammatory states: tenderness and neurogenic inflammation. J Physiol Sci. 2006;56(4):317-320. 9. Kim H-Y, Hahm D-H, Pyun D-H et al. Effects of acupuncture at GV01 on experimentally induced colitis in rats: possible involvement of the opioids system. Japanese Journal of Physiology. 2005;55:205-210. 10. Park E-S et al. Effect of acupuncture in the treatment of young pigs with induced Escherichia coli diarrhea. J Vet Sci. 2003;4(2):125-128. 11. Ding D. Treatment of infantile diarrhea by acupuncture and laser irradiation – a report of 60 cases. J Tradit Chin Med. 2004;24(4):280-281. 12. Prokic B et al. Idiopathic and secondary acquired megacolon in dogs is associated with diminished vasoactive intestinal polypeptide innervation of the affected colon. Acta Veterinaria (Beograd). 2009;59(1):53-68. 13. Wood JD. Neuropathophysiology of functional gastrointestinal disorders. Editorial. World J Gastroenterol. 2007;13(9):1313-1332. 14. Chen J, Song G-Q, Yin J, et al. Electroacupuncture improves impaired gastric motility and slow waves induced by rectal distension in dogs. Am J Physiol Gastrointest Liver Physiol. 2008;295:G614-G620. 15. Qian L, Peters LJ, and Chen JDZ. Effects of electroacupuncture on gastric migrating myoelectrical complex in dogs. Digestive Diseases and Sciences. 1999;44(1):56-62. 16. Takahashi T. Acupuncture for functional gastrointestinal disorders. J Gastroenterol. 2006;41:408-417. 17. Luo D, Liu S, Xie X, et al. Electroacupuncture at acupoint ST-36 promotes contractility of distal colon via a cholinergic pathway in conscious rats. Dig Dis Sci. 2008;53:689-693. 18. Zhou W, Mahajan A, and Longhurst JC. Spinal nociception mediates electroacupuncture-related modulation of visceral sympathoexcitatory reflex responses in rats. Am J Physiol Heart Circ Physiol. 2009;297:H859-H865. 19. Ayas S, Leblebici B, Sozay S, et al. The effect of abdominal massage on bowel function in patients with spinal cord injury. Am J Phys Med and Rehab. 2006;85(12):951-955. 20. Diego MA, Field T, Hernandez-Reif M, et al. Preterm infant massage elicits consistent increases in vagal activity and gastric motility that are associated with greater weight gain. Acta Paediatrica. 2007;96:1588-1591. 21. Lamas K, Lindholm L, Engstrom B, et al. Abdominal massage for people with constipation: a cost utility analysis. J Advanced Nursing. 2010;66(8):1719-1729. 22. Pfab F, Winhard M, Nowak-Machen M, et al. Acupuncture in critically ill patients improves delayed gastric emptying: a randomized controlled trial. Anesth Analg. 2010 Nov 16. [Epub ahead of print]. 23. Dickman R, Schiff E, Holland A, et al. Clinical trial: acupuncture vs. doubling the proton pump inhibitor dose in refractory heartburn. Alimentary Pharmacology & Therapeutics. 2007;26:1333-1344. 24. Wang C, Zhou DF, Shuaie XW, et al. Effects and mechanisms of electroacupuncture at PC6 on frequency of transient lower esophageal sphincter relaxation in cats. World J Gastroenterol. 2007; 13(36):4873-4880.
