Colonic motor dysfunction in human diabetes is associated with enteric neuronal loss and increased oxidative stress

• Published in: Neurogastroenterology and motility 2011-02, Vol.23 (2), p.131-e26
• Main Authors: Chandrasekharan, B., Anitha, M., Blatt, R., Shahnavaz, N., Kooby, D., Staley, C., Mwangi, S., Jones, D. P., Sitaraman, S. V., Srinivasan, S.
• Format: Article
• Language: English
• Subjects: Aged; Animals; Antioxidants; Antioxidants - pharmacology; Apoptosis; Apoptosis - drug effects; Biopsy; Case-Control Studies; Caspase-3; Cell Line; Choline; Colon; Colon - innervation; Colon - physiopathology; Constipation; Data processing; diabetes; Diabetes Complications - complications; Diabetes mellitus; Diarrhea; Disease Models, Animal; Electric Stimulation; Enteric nervous system; Enteric Nervous System - drug effects; Enteric Nervous System - pathology; Enteric Nervous System - physiopathology; enteric neurons; Female; Ganglia; Gastrointestinal Diseases - etiology; Gastrointestinal Diseases - pathology; Gastrointestinal Diseases - physiopathology; Gastrointestinal tract diseases; Glutathione; Humans; Hyperglycemia; Intestine; Lasers; Lipoic acid; Male; Mice; Middle Aged; Motility; mRNA; Muscle contraction; Muscle Contraction - physiology; Muscle Relaxation - physiology; Neurons; Neuropeptide Y; Nitric-oxide synthase; Oxidative stress; Oxidative Stress - physiology; Peripherin; Phosphatidylinositol 3-Kinases - physiology; Reactive Oxygen Species - metabolism; Signal Transduction - physiology; Superoxide dismutase; Surgery; Thioctic Acid - pharmacology; Vasoactive intestinal peptide; Western blotting
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/j.1365-2982.2010.01611.x

Background  Gastrointestinal dysfunction is very common in diabetic patients. We assessed the changes in the colonic enteric nervous system using colectomy specimens and intestinal biopsies from diabetic subjects and age‐matched controls. Methods  In control and diabetic colons, we determined the total ganglion area (hematoxylin–eosin staining), changes in neuronal markers–protein gene product 9.5, peripherin, neuronal nitric oxide synthase (nNOS), neuropeptide Y (NPY), choline acetyl transferase (ChAT) and vasoactive intestinal peptide (by immunostaining), apoptosis (cleaved caspase‐3 staining) and reduced glutathione levels. Superoxide dismutase mRNA was determined in enteric ganglia isolated by laser capture micro dissection. Isometric muscle recording was used to assess contraction and relaxation responses of colonic circular muscle strips. Apoptosis in enteric neurons under hyperglycemia in vitro was determined by cleaved caspase‐3 Western blotting and protective effects of lipoic acid were evaluated. Key Results  Diabetic subjects had higher incidence of lower gastrointestinal symptoms like constipation and diarrhea at baseline prior to surgery. Diabetic ganglia displayed significant decrease in ganglion size due to enhanced apoptosis and loss of peripherin, nNOS, NPY, and ChAT neurons. Reduced glutathione levels in the diabetic colon (HbA1C > 7%) were significantly less than the control, indicating increased oxidative stress. Colonic circular muscle strips from diabetic subjects showed impaired contraction and relaxation responses compared with the healthy controls. Hyperglycemia‐induced cleaved caspase‐3 in enteric neurons was reversed by lipoic acid. Conclusions & Inferences  Our data demonstrate loss of enteric neurons in the colon due to increased oxidative stress and apoptosis which may cause the motility disturbances seen in human diabetes. Antioxidants may be of therapeutic value for preventing motility disorders in diabetes.