Effects of pioglitazone on myocardial energy metabolism and hemodynamics in rats with myocardial infarction

AIM: To observe the effects of pioglitazone on myocardial energy metabolism and hemodynamics in rats with heart failure after myocardial infarction (MI). METHODS: The model of MI was established by ligation of left anterior descending artery. The 20 surviving rats were randomly divided into MI group (n=10) and pioglitazone intervention group (P group,n=10, pioglitazone 3 mg·kg^-1·d^-1 orally). The sham-operated rats (SH, n=10) served as controls. Hemodynamic parameters were measured. The ratio of left ventricular weight to body weight (LVW/BW) and the ratio of right ventricular weight to body weight (RVW/BW) were calculated after 8-week treatment. The expression of PPARγ was examined by Western blotting. Mitochondrial respiratory function was determined by Clark oxygen electrodes. The size of adenine acid pool (ATP, ADP and AMP) in mitochondria was measured by HPLC. The adenine nucleotide translocator(ANT) activity was detected by the atractyloside-inhibitor stop technique. RESULTS: Compared with SH group, the protein expression of PPARγ was significantly decreased in MI group (P<0.01). The mitochondrial respiratory activity, the transport activity of ANT and the high-energy phosphate content were decreased in MI group (P<0.01), and the hemodynamic parameters were in disorder (P<0.01). Compared with MI group, the protein expression of PPARγ in P group was significantly increased. The mitochondrial respiratory activity, the high-energy phosphate content, the transport activity of ANT were improved (P<0.01). However, the hemodynamic parameters were not significantly changed.CONCLUSION: Pioglitazone increases the protein expression of PPARγ and improves myocardial energy metabolism in the development of heart failure in the rat model of myocardial infarction, but dose not change the hemodynamic parameters significantly.     

Effect of preconditioning with pioglitazone on ischemia reperfusion/hypoxia reoxygenation-induced mitochondrial structure and membrane potential in rats

AIM: To observe the effect of preconditioning with pioglitazone on ischemia reperfusion/hypoxia reoxygenation-induced mitochondrial ultramicro-structure and membrane potential in rats. METHODS: Sprague-Dawley rats were randomly divided into four groups: sham-operated (SO) group, ischemia reperfusion (IR) group, pioglitazone preconditioning group (Pio-P) and 5-HD+pioglitazone (5-HD+Pio) group. Apart from the SO group, IR, Pio-P and 5-HD+Pio groups were subjected to 30 min ischemia and 4 h reperfusion. The heart was quickly removed for observing the structure of mitochondria and measurement of the apoptosis index (AI) by TUNEL. Primary cultured cardiomyocytes of Sprague-Dawley rats were divided into control, hypoxic reoxygenation (HR) and different concentrations of Pio-P group. JC-1 staining flowcytometry was adopted to examine mitochondrial membrane potential (ΔΨm). RESULTS: The injury of mitochondrial structure in IR group was severer than that in Pio-P group, while the difference between 5-HD+Pio group and IR group was not evident. Flameng score in Pio-P group(1.62±0.60) was significantly lower than that in IR group (2.75±1.09), P<0.01. AI in Pio-P group (28.19%±4.93%) was lower than that in IR group (55.44%±6.63%),P<0.05. The rates of low ΔΨm cells in (5 μmol/L,10 μmol/L and 15 μmol/L) Pio-P group were (45.89±3.63)%, (17.13±1.37)% and (18.43±2.44)%, significantly lower than that in HR group (56.52%±2.87%),P<0.05, while the difference between 10 μmol/L group and 15 μmol/L group was not significant (P>0.05). CONCLUSION: Pioglitazone protects the heart from ischemia reperfusion/ hypoxia reoxygenation injury evidenced by improving mitochondrial ultrastructure and lessening the loss of mitochondrial membrane potential, and decreasing apoptosis. The cardioprotective effects can be inhibited by the blocker of mitochondrial ATP-sensitive potassium channels.     

Effect of pioglitazone on pre-adipocytes differentiation and GILZ expression

AIM: To investigate the roles of pioglitazone on differentiation and expression of GILZ in 3T3-L1 pre-adipocytes. METHODS: The morphological changes during 3T3-L1 cell differentiation were observed. The cells were treated with pioglitazone at concentrations of 1×10^-4～1×10^-2 mmol/L for 48 h, then the relative content of triglyceride were analyzed by oil red O staining at 2nd, 4th and 6th day during adipogenesis. The mRNA expression of peroxisome proliferator-activated receptor γ2 (PPARγ2) and lipoprotein lipase (LPL) was measured by real-time PCR. GILZ protein expression was determined by Western blot after the cells were treated with pioglitazone at concentrations of 1×10^-4 ～1×10^-2 mmol/L for 48 h.RESULTS: Oil-red O staining showed that the relative contents of triglyceride in adipocytes were increased with the increase in the pioglitazone concentration. Compared with the control, the relative contents of triglyceride in group 1×10^-3 mmol/L and group 1×10^-2 mmol/L were significantly increased (P < 0.05). The mRNA expression of PPARγ2 and LPL was also increased with the increase in the pioglitazone concentration. When pioglitazone concentration was more than 1×10^-3 mmol/L, compared with the control, the mRNA expression of PPARγ2 and LPL significantly increased (P < 0.01). The protein expression of GILZ was decreased with the increase in the pioglitazone concentration.CONCLUSION: Pioglitazone down-regulates GILZ expression, and up-regulate PPARγ2 expression and the downstream functional factor such as LPL.     

Effects and mechanism of fenofibrate and pioglitazone on ventricular remodelingin in pressure overload rats

AIM: To study the effects and mechanism of peroxisome proliferator-activated receptors (PPARs) ligands,fenofibrate and pioglitazone,on ventricular remodeling in pressure overload rats.METHODS: A pressure overload model was established by the constriction of abdominal aorta in Wistar rats.The hemodynamics and ventricular remodeling parameters,plasma and myocardial renin activity,angiotensin Ⅱ and aldosteron,the mRNA expression of angiotensin Ⅱ type 1 receptor (AT1) were investigated in the constriction of abdominal aorta group (CAA group,n=7) at 12-week after operation and treated experimental groups in which rats were treated with fenofibrate (F group,n=8),pioglitazone (P group,n=7),concomitant fenofibrate and pioglitazone (F+P group,n=6) for 12 weeks since 2 days after operation.The sham-operated rats served as controls (n=8).RESULTS: The ratio of left ventricular weight to body weight,mean arterial pressure,left ventricular systolic pressure,left ventricular end diastolic pressure,left ventricular systolic pressure and heart rate were significantly lower,the maximum left ventricular pressure rising and declining rates(±dp/dtmax) were significantly higher in all treated experimental groups than those in CAA group.Fenofibrate or pioglitazone had no effect on plasma and myocardial levels of renin,angiotensin Ⅱand aldosteron.The mRNA expression of AT1 was downregulated in treated groups except F group.CONCLUSION: PPAR ligands have no effect on plasma and myocardial levels of renin,angiotensin Ⅱand aldosteron,but fenofibrate and pioglitazone inhibit ventricular remodeling,decrease preload and afterload,increase ±dp/dtmax in pressure overload rats.The expression of mRNA of AT1 is downregulated in myocardium of pressure overload rats by the PPARγ signaling pathway.     

Effect of pioglitazone on balance of regulatory and effector T cells of uremic apolipoprotein E knockout mice in vitro

AIM: To investigate the effects of pioglitazone on the quantity and function-related factors of regulatory and effector T cells (Treg and Teff ) of uremic apolipoprotein E knockout mice in vitro with or without the stimulation of atherosclerotic plaque-specific antigen oxidized low-density lipoprotein (oxLDL). METHODS: Uremic apolipoprotein E knockout mouse model was established by 2-step surgical procedure. After intervention with different concentrations (2 μmol/L and 20 μmol/L) of pioglitazone and PPARγ antagonist GW9662 (5 μmol/L) on splenocytes of uremic mice for 12 h in the presence or absence of oxLDL (2 mg/L), the levels of CD4⁺ CD25⁺ Foxp3⁺ Treg and IFNγ⁺ CD4⁺ Teff were determined by flow cytometry. The mRNA expressions of Foxp3 and IFNγ was detected by real-time fluorescent quantitative PCR. RESULTS: In vitro, oxLDL induced a Treg/Teff imbalance in splenocytes from the uremic mice. Pioglitazone upregulated the level of Treg and mRNA expression of Foxp3 in the presence of oxLDL, which was not antagonized by GW9662. Meanwhile, pioglitazone downregulated the level of Teff and mRNA expression of IFNγ in the presence or absence of oxLDL, which was reversed by GW9662. CONCLUSION: oxLDL induces a Treg/Teff imbalance in uremic apolipoprotein E knockout mice. Pioglitazone modulates the Treg/Teff imbalance probably through PPARγ-independent and-dependent mechanisms.     

Protective effects of pioglitazone on endothelial function in rats with hypercholesterolemia

AIM: To investigate the effects of pioglitazone,a PPARγ agonist,on endothelial cell (EC) dysfunction in hypercholesterolemic rats.METHODS: 36 healthy male Wistar rats were assigned to one of the following groups randomly (six rats in each group): control,hypercholesterolemia (HC),and HC treated with pioglitazone 1.5 mg·kg^-1·d^-1,3 mg·kg^-1·d^-1,10 mg·kg^-1·d^-1 and 20 mg·kg^-1·d^-1 (HC＋PIO),respectively.EC function was determined by comparing vasorelaxation to ACh,an EC dependent vasodilator,and acidified NaNO₂,an EC-independent vasodilator.Maximal positive and negative values of the instantaneous first derivative of LVP (+dp/dt_max and dp/dt_max) were determined by MS2000 system.RESULTS: (1) Hypercholesterolemia caused a significant endothelial diastolic dysfunction (maximal relaxation to ACh: 50.51%±2.45% vs 99.78%±3.01% in control,P<0.01).(2) Treatment with pioglitazone relieved EC-dependent vasodilatation in a dose dependent manner,and 10 mg·kg^-1·d^-1 is the best dose.(3) Pioglitazone not only improved EC function,but also reduced cardiac functional injury induced by hypercholesterolemia.CONCLUSION: EC dysfunction induced by hypercholesterolemia can be directly extenuated by pioglitazone,which may effectively prevent from subsequent atherosclerosis and ischemic heart disease.     

Dietary supplementation with pioglitazone hydrochloride and l-carnosine improves the growth performance,muscle fatty acid profiles and shelf life of yellow-feathered broiler chickens

The present study aimed to investigate the effects of dietary pioglitazone hydrochloride (PGZ) and l-carnosine (LC) supplementation on the growth performance, meat quality, antioxidant status, and meat shelf life of yellow-feathered broiler chickens. Five hundred broiler chickens were randomly assigned into 4 experimental diets using a 2 × 2 factorial arrangement with 2 PGZ supplemental levels (0 and 15 mg/kg) and 2 LC supplemental levels (0 and 400 mg/kg) in basal diets for 28 d. The feed-to-gain ratio decreased whereas the average daily gain increased with PGZ supplementation. Greater dressing percentages, contents of intramuscular fat (IMF) in breast and thigh muscles, C18:3n-6, C18:1n-9 and monounsaturated fatty acid (MUFA) percentages of thigh muscle were observed with PGZ addition. Additionally, significant synergistic effects between PGZ and LC on the C18:1n-9 and MUFA contents were found. Supplementation with LC decreased drip loss, cooking loss and total volatile basic nitrogen, and increased the redness (a∗) value, the superoxide dismutase and glutathione peroxidase activities in thigh muscles. Moreover, the malondialdehyde content decreased when diets were supplemented with LC, and there was a synergistic effect between PGZ and LC. Additionally, the mRNA abundance of lipogenesis-related genes, such as peroxisome proliferator-activated receptor γ (PPARγ), PPARγ co-activator 1α and fatty acid-binding protein 3, increased with PGZ supplementation, and relevant antioxidation genes, such as nuclear factor erythroid-2-related factor 2 and superoxide dismutase 1, were enhanced with LC supplementation. In conclusion, the results indicated that the supplementation of PGZ and LC could improve the growth performance, antioxidant ability, IMF content, and meat shelf life of yellow-feathered broiler chickens.