[Influence of siRNA-mediated PPARgamma gene knockdown on insulin resistance induced by myocardial ischemia-reperfusion in rats].
OBJECTIVE
To observe the influenece of siRNA-mediated PPARgamma gene knockdown on insulin resistance induced by myocardial ischemia-reperfusion in adult rats.


METHODS
The targeting PPARgamma siRNA was synthesized. The myocardial cells of adult rats were isolated and cultured. They were divided into four groups: IRI group, siRNA-PPARgamma group, empty group and blank control group. Two groups of rat cardiac cells were transfected with PPARgamma-targeting siRNA (siRNA-PPARgamma group), or empty small interfering RNA (NC group), respectively. Real-time quantitive PCR was performed to detect the mRNA levels of PPARgamma and GLUT-4. PPARgamma protein expression level was determined with Western blot test. The uptake rate of glucose was determined by the isotope tracer method.


RESULTS
The PPARgamma mRNA and protein expression of IRI group were significantly higher than those in blank control group (P < 0.05). The PPARgamma mRNA and protein expression of siRNA-PPARgamma group were significantly less than those in blank control and IRI group (P < 0.01). There was no significant difference in the PPARgamma mRNA and protein expression between the blank group and IRI group. The mRNA expression of GLUT-4 in blank control was no significant difference at each time point. The mRNA expression of GLUT-4 in IRI group was significantly less at 0 min, but increased gradually over the following time point. Finally, The mRNA expression of GLUT-4 in IRI group restored the same level as blank control. There was no significant difference in the GLUT-4 mRNA expression between the empty group and IRI group. The GLUT-4 mRNA expression in siRNA-PPARgamma group was significantly less than that in IRI group or NC group (P < 0.05), and recovered more slowly than IRI group. After given insulin, The uptake rate of glucose in siRNA-PPARgamma group was significantly less at each time point compared with those in IRI group (P < 0.05), declined by 49.78%, 38.94%, 18.61%, 11.54% at 0 min, 15 min, 1 h, 2 h, respectively. At 6 h time point, the uptake rate of glucose in siRNA-PPARgamma group reached the same level as IRI group. There was no significant difference was observed in the uptake rate of glucose between the empty group and IRI group.


CONCLUSIONS
The siRNA-mediated PPARgamma gene knockdown may enhance the myocardial insulin resistance. The molecular mechanisms that trigger myocardial cell insulin resistance might because the silence of PPARgamma expression decreasing the expression of GLUT-4 and decline its transportation from cytoplasm to membrane.
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Jian
J
Zhang
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Quan
Q
Tang
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Gui-You
GY
Liang
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Da-Ring
DR
Liu
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Feng
F
Wang
Laboratory of Pharmacology, Zunyi Medical College, Zunyi 563003, China.
Qinz
Q
Wu
Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Gang
G
Yao
Department of Thoracic and Cardiovascular Surgery, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Deng-Shen
DS
Zhang
D000818:Animals; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance / Q000235:genetics*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000235:genetics*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D047495:PPAR gamma / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014162:Transfection
D051275:Glucose Transporter Type 4; D047495:PPAR gamma; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C495694:Slc2a4 protein, rat