Ganglioside GM3 content in skeletal muscles is increased in type 2 but decreased in type 1 diabetes rat models: I mplications of glycosphingolipid metabolism in pathophysiology of diabetes 骨骼肌中神经节苷脂GM3的含量在2型糖尿病大鼠模型中增加但在1型糖尿病大鼠模型中减少:鞘糖脂代谢在糖尿病病理生理学中的作用

• Published in: Journal of diabetes Vol. 10; no. 2; pp. 130 - 139
• Main Authors: Bozic, Josko, Markotic, Anita, Cikes‐Culic, Vedrana, Novak, Anela, Borovac, Josip A., Vucemilovic, Hrvoje, Trgo, Gorana, Ticinovic Kurir, Tina
• Format: Journal Article
• Language: English
• Published: 01-02-2018
• ISSN: 1753-0393; 1753-0407
• DOI: 10.1111/1753-0407.12569

Abstract
Background
Ganglioside
GM3
is found in the plasma membrane, where its accumulation attenuates insulin receptor signaling. Considering the role of skeletal muscles in insulin‐stimulated glucose uptake, the aim of the present study was to determine the expression of
GM3
and its precursors in skeletal muscles of rat models of type 1 and type 2 diabetes mellitus (
T1DM
and
T2DM
, respectively).
Methods
Diabetes was induced in male
S
prague‐
D
awley rats by streptozotocin injection (55 mg/kg, i.p., for
T1DM
induction; 35 mg/kg, i.p., for
T2DM
induction), followed by feeding of rats with either a normal pellet diet (
T1DM
) or a high‐fat diet (
T2DM
). Rats were killed 2 weeks after diabetes induction and samples of skeletal muscle were collected. Frozen quadriceps muscle sections were stained with a primary antibody against
GM3
(
Neu5Ac
) and visualized using a secondary antibody coupled with
T
exas
R
ed. The muscle content of ganglioside
GM3
and its precursors was analyzed by high‐performance thin‐layer chromatography (
HPTLC
) followed by
GM3
immunostaining.
Results
Muscle
GM3
content was significantly higher in
T2DM
compared with control rats (
P

<
 0.001). Furthermore, levels of the
GM3
precursors ceramide, glucosylceramide, and lactosylceramide were significantly higher in
T2DM
compared with control rats (
P

<
 0.05), whereas ceramide content was significantly lower in
T1DM
rats (
P

<
 0.05). The intensity of the
GM3
band on
HPTLC
was significantly higher in
T2DM
rats (
P
 < 0.001) and significantly lower in
T1DM
rats (
P

<
 0.05) compared with control.
Conclusions
The expression patterns of
GM3
ganglioside and its precursors in diabetic rats suggest that the role of glycosphingolipid metabolism may differ between
T2DM
and
T1DM
.
摘要
背景
神经节苷脂GM3在细胞膜上表达,  它在细胞膜上积聚可以减弱胰岛素受体的信号传导。考虑到骨骼肌在胰岛素刺激后的葡萄糖摄取中所起到的作用,  本研究旨在检测GM3及其前体在1型与2型糖尿病(分别缩写为T1DM与T2DM)大鼠模型骨骼肌中的表达。
方法
雄性Sprague‐Dawley大鼠注射链脲霉素后诱导糖尿病(腹腔内注射55 mg/kg诱导T1DM;腹腔内注射35 mg/kg诱导T2DM),  然后分别用正常饲料(T1DM)或者高脂饲料(T2DM)进行饲养。诱导出糖尿病2周之后,  将大鼠处死并且收集骨骼肌样本进行实验。使用一级抗GM3抗体(Neu5Ac)对冰冻四头肌切片进行染色,  使用与德克萨斯红偶联的二级抗体显影。使用高效薄层色谱法以及GM3免疫染色法分析肌肉中神经节苷脂GM3及其前体含量。
结果
T2DM大鼠肌肉中的GM3含量显著高于对照组大鼠(
P
< 0.001)。此外,  T2DM大鼠GM3前体神经酰胺、葡萄糖基神经酰胺以及乳糖基神经酰胺的水平也显著高于对照组大鼠(
P
< 0.05),  然而T1DM大鼠的神经酰胺含量却显著降低(
P
< 0.05)。与对照组大鼠相比,  使用高效薄层色谱法分析后发现T2DM大鼠的GM3条带强度显著增强(
P
< 0.001),  而T1DM大鼠中却显明显减弱(
P
< 0.05)。
结论
不同类型糖尿病大鼠的GM3神经节苷脂及其前体表达模式各不相同,  提示鞘糖脂代谢在T2DM与T1DM中的作用可能存在差异。