Scanning electron microscopic analysis of intramyocellular lipid droplets in an animal model of type 2 diabetes.
OBJECTIVE
To evaluate the accumulation pattern of intramyocellular lipids (IMCLs) in striated muscle during the development and progression of diabetes, using a novel scanning electron microscopic method.


METHODS
Hyperglycemia was induced by feeding diabetes-prone (DP) Psammomys obesus a high-energy (HE) diet. Lipid accumulation within gastrocnemius muscle fibers was assessed in formalin-fixed muscle samples during the development of hyperglycemia using high resolution imaging in a scanning electron microscope. We evaluated the temporal relationship between changes in IMCL quantity and morphology and the altered glucose metabolism and assessed the effect of reversal of hyperglycemia on IMCL level and morphology. Diabetes-resistant (DR) P. obesus served as controls.


RESULTS
Lipid accumulation in the muscle fibers of DP animals was increased with the development of hyperglycemia. This was characterized by increased lipid density as well as by an abundance of large lipid droplets. Reversal of the phenotype resulted in the disappearance of large lipid droplets. The IMCL level and the distribution of lipid droplet size were similar in muscles of both the normoglycemic DR and DP animals, with an abundance of small lipid droplets. This profile was changed following a HE diet only in the DP animals.


CONCLUSIONS
Lipid accumulation in the muscle of P. obesus during the development of hyperglycemia is characterized by increased quantity and accumulation of large lipid droplets. These changes were reversible upon normalization of blood glucose. The evaluated methodology is a useful tool for the study of the dynamics of lipid accumulation in different metabolic conditions.
Fraenkel
Merav
M
Endocrinology and Metabolism Service, Department of Internal Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Weiss
Ram
R
Leizerman
Ilit
I
Anaby
Debbie
D
Golomb
Eliahu
E
Leibowitz
Gil
G
Kaiser
Nurit
N
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology*; D004195:Disease Models, Animal; D018450:Disease Progression; D002149:Energy Intake; D005849:Gerbillinae; D006943:Hyperglycemia / Q000378:metabolism / Q000473:pathology*; D007328:Insulin / Q000097:blood; D050356:Lipid Metabolism; D008297:Male; D008855:Microscopy, Electron, Scanning; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000648:ultrastructure*; D010641:Phenotype; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin