title: Psyllium and fat in diets differentially affect the activities and expressions of colonic sphingomyelinases and caspase in mice.
abstract: Dietary fibre and fat affect colonic tumourigenesis and inflammation. Sphingomyelin metabolism may have implications for the pathogenesis of colonic tumours and ulcerative colitis. The present study examined the effects of psyllium and fat on the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. Mice were fed control, psyllium-containing (100 g/kg), high-fat (313 g/kg, 53 % energy as fat) or high-fat plus psyllium diets for 4 weeks. The activities of acid, neutral and alkaline sphingomyelinase (SMase), neutral ceramidase, and caspase 3, 8 and 9 in colonic mucosa were determined. The expressions of alkaline SMase and caspase 3 were examined. The psyllium-containing diet was found to increase significantly the activities of alkaline SMase and caspase 3 and decreased those of acid SMase and neutral ceramidase. The high-fat diet had opposite effects on these enzymes and attenuated the effects of psyllium. Western blotting showed that psyllium increased and high-fat decreased the levels of alkaline SMase and caspase 3 in colonic mucosa. The change in caspase 3 activity was positively correlated with that of alkaline SMase and negatively with acid SMase. No similar changes of acid and alkaline phosphatase activities in the colon or acid and neutral SMase activity in the liver were identified. In conclusion, colonic sphingomyelin metabolism and apoptosis were affected by psyllium and fat in an opposite manner. The results may have implications for colorectal tumourigenesis and inflammation.
authors.affiliation: Gastroenterology and Nutrition Laboratory, Biomedical Centre, B11, Lund University, S-22184 Lund, Sweden.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Cheng
authors.forename: Lena
authors.initials: L
authors.lastname: Ohlsson
authors.forename: Rui-Dong
authors.initials: RD
authors.lastname: Duan
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D055572:Ceramidases; D003106:Colon / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000201:enzymology; D007422:Intestines / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D051379:Mice; D055576:Neutral Ceramidase; D011620:Psyllium / Q000008:administration & dosage / Q000494:pharmacology*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D013109:Sphingomyelins; D011620:Psyllium; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D013108:Sphingomyelin Phosphodiesterase; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D000581:Amidohydrolases; C526747:Asah2 protein, mouse; D055572:Ceramidases; D055576:Neutral Ceramidase