Role of lipids in the early developmental stages of experimental immune diabetes induced by multiple low-dose streptozotocin.
The present work examines the role of lipids in the development of the Type 1 diabetes induced by the administration of multiple low doses of streptozotocin (STZ) in C57BL/6J mice. The study was performed before and after the onset of clear hyperglycemia, and the results were as follows. First, 6 days after the first dose of STZ, while plasma glucose and insulin levels remained similar to those observed in the control mice, plasma free fatty acid (FFA) levels were significantly increased (P < 0.05). At that time, a marked increase of triglyceride content in gastronemius muscle was accompanied by a diminished activity of pyruvate dehydrogenase complex, suggesting an impaired glucose oxidation. Furthermore, a decrease of both triglyceride content and lipoprotein lipase activity was observed in the epididymal fat tissue. Second, 12 days after the first injection of STZ, hyperglycemia was accompanied by hypertriglyceridemia, a more pronounced increase of plasma FFA, and a significant (P < 0.05) reduction of insulinemia. At this time, both the adipose tissue and the gastrocnemius muscle showed a further deterioration of all parameters mentioned after 6 days. Moreover, in the gastrocnemius muscle, an impaired nonoxidative pathway of glucose metabolism was observed [significant reduction (P < 0.05) of glycogen mass, glucose-6-phosphate content, and glycogen synthase activities] at this time point. Finally, the data suggest for the first time that, in mice, Type 1 diabetes induced by multiple low doses of STZ and enhanced lipolysis of fat pads leads to an increase in the availability of plasma FFA, which seems to play a role in the early steps of diabetes evolution.
Pighin
Dario
D
School of Biochemistry, University of Litoral, Ciudad Universitaria Paraje El Pozo, CC 242, 3000 Santa Fe, Argentina.
Karabatas
Liliana
L
Pastorale
Claudia
C
Dascal
Eduardo
E
Carbone
Cecilia
C
Chicco
Adriana
A
Lombardo
Yolanda B
YB
Basabe
Juan Carlos
JC
D000818:Animals; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000139:chemically induced / Q000378:metabolism*; D018450:Disease Progression; D007515:Islets of Langerhans / Q000378:metabolism*; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012720:Severity of Illness Index; D013311:Streptozocin
D013311:Streptozocin