Altered TNF-alpha, glucose, insulin, and amino acids in islets of Langerhans cultured in a microgravity model system.
The present studies were designed to determine effects of a microgravity model system upon lipopolysaccharide (LPS)-stimulated tumor necrosis factor-alpha (TNF-alpha) activity and indexes of insulin and fuel homeostasis of pancreatic islets of Langerhans. Islets (1,726 +/- 117, 150 islet equivalent units) from Wistar-Furth rats were treated as 1) high aspect ratio vessel (HARV) cell culture, 2) HARV plus LPS, 3) static culture, and 4) static culture plus LPS. TNF-alpha (L929 cytotoxicity assay) was significantly increased in LPS-induced HARV and static cultures; yet the increase was more pronounced in the static culture group (P < 0.05). A decrease in insulin concentration was demonstrated in the LPS-stimulated HARV culture (P < 0.05). We observed a greater glucose concentration and increased disappearance of arginine in islets cultured in HARVs. Although nitrogenous compound analysis indicated a ubiquitous reliance on glutamine in all experimental groups, arginine was converted to ornithine at a twofold greater rate in the islets cultured in the HARV microgravity model system (P < 0.05). These studies demonstrate alterations in LPS-induced TNF-alpha production of pancreatic islets of Langerhans, favoring a lesser TNF activity in the HARV. These alterations in fuel homeostasis may be promulgated by gravity-averaged cell culture methods or by three-dimensional cell assembly.
Tobin
B W
BW
Diabetes Research Laboratory, Program in Nutrition and Biochemistry, Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia 31207, USA. tobin.b@gain.mercer.edu
Leeper-Woodford
S K
SK
Hashemi
B B
BB
Smith
S M
SM
Sams
C F
CF
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002469:Cell Separation; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D017672:Nitrogen Compounds / Q000378:metabolism; D010180:Pancreatectomy; D051381:Rats; D011920:Rats, Inbred WF; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D018474:Weightlessness Simulation
D000596:Amino Acids; D007328:Insulin; D007773:Lactates; D008070:Lipopolysaccharides; D017672:Nitrogen Compounds; D014409:Tumor Necrosis Factor-alpha; D007770:L-Lactate Dehydrogenase; D005947:Glucose