• Proceedings of the PSK Conference
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• 2003.10b
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• pp.177.2-177.2
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• 2003

Thiazolidinediones (TZDs) are a new class of compound that increase insulin sensitivity in type 2 diabetic patients. Thiazolidinediones (TZDs) act as ligands for a member of the nuclear hormone receptor superfamily, peroxisome proliferator-activated receptor-$\gamma$ (PPAR-$\gamma$), which is highly expressed in fatty tissue and, moreover, has been shown to play an important role in fat cell differentiation. The strong interaction between the antidiabetic activity ofTZDs and their ability to activate PPAR-$\gamma$ suggests that PPAR-$\gamma$, through downstream-regulated genes, mediates the effects of TZDs. (omitted)

• BMB Reports
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• v.47 no.11
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• pp.599-608
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• 2014

As the prevalence of obesity has increased explosively over the last several decades, associated metabolic disorders, including type 2 diabetes, dyslipidemia, hypertension, and cardiovascular diseases, have been also increased. Thus, new strategies for preventing and treating them are needed. The nuclear peroxisome proliferator-activated receptors (PPARs) are involved fundamentally in regulating energy homeostasis; thus, they have been considered attractive drug targets for addressing metabolic disorders. Among the PPARs, $PPAR{\gamma}$ is a master regulator of gene expression for metabolism, inflammation, and other pathways in many cell types, especially adipocytes. It is a physiological receptor of the potent anti-diabetic drugs of the thiazolidinediones (TZDs) class, including rosiglitazone (Avandia). However, TZDs have undesirable and severe side effects, such as weight gain, fluid retention, and cardiovascular dysfunction. Recently, many reports have suggested that $PPAR{\gamma}$ could be modulated by post-translational modifications (PTMs), and modulation of PTM has been considered as novel approaches for treating metabolic disorders with fewer side effects than the TZDs. In this review, we discuss how PTM of $PPAR{\gamma}$ may be regulated and issues to be considered in making novel anti-diabetic drugs that can modulate the PTM of $PPAR{\gamma}$.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.3
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• pp.432-439
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• 2007

Thiazolidinediones (TZDs) act as potent activators of the adipose differentiation program in established preadipose cell lines. TZD's have also been investigated in diabetic patients and reported to act as PPAR-${\gamma}$ ligands. In this report, the effects of TZDs on the differentiation pathway of myoblasts have been investigated. C2C12 mouse myoblasts were grown in Dulbecco's Modified Eagles medium for 4-5 days until they reached almost 100% confluency. Post-confluent cells (day 0) were further exposed to adipogenic induction medium along with TZDs for 48 hours. Thereafter, cells were exposed only to TZDs every 48 h until day 10. The control was provided with differentiation medium without any treatment. Alterations in the cells during the differentiation programme were analyzed on the basis of fusion index, oil-red-o staining, adipocyte index, adipocyte stain uptake measurement, immuno-histochemistry and western blotting. Exposure of C2C12 mouse myoblasts to TZDs prevented the expression of myosin heavy chain with parallel increase in the expression of C/EBP-${\alpha}$ and PPAR-${\gamma}$ and acquisition of adipocyte morphology, thus abolishing the formation of multinucleated myotubes. TZDs exert their adipogenic effects only in non-terminally differentiated myoblasts; myotubes were insensitive to the compound. Continuous exposure (at least 4-5 doses) to inducers after the growth arrest was essential to provide a sustained environment to the cells converting to fully matured adipoctyes. The results indicate that TZDs specifically converted the differentiation pathway of myoblasts into that of adipoblasts.

• Molecules and Cells
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• v.41 no.10
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• pp.900-908
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• 2018

Insulin resistance is closely associated with metabolic diseases such as type 2 diabetes, dyslipidemia, hypertension and atherosclerosis. Thiazolidinediones (TZDs) have been developed to ameliorate insulin resistance by activation of peroxisome proliferator-activated receptor (PPAR) ${\gamma}$. Although TZDs are synthetic ligands for $PPAR{\gamma}$, metabolic outcomes of each TZD are different. Moreover, there are lack of head-to-head comparative studies among TZDs in the aspect of metabolic outcomes. In this study, we analyzed the effects of three TZDs, including lobeglitazone (Lobe), rosiglitazone (Rosi), and pioglitazone (Pio) on metabolic and thermogenic regulation. In adipocytes, Lobe more potently stimulated adipogenesis and insulin-dependent glucose uptake than Rosi and Pio. In the presence of pro-inflammatory stimuli, Lobe efficiently suppressed expressions of pro-inflammatory genes in macrophages and adipocytes. In obese and diabetic db/db mice, Lobe effectively promoted insulin-stimulated glucose uptake and suppressed pro-inflammatory responses in epididymal white adipose tissue (EAT), leading to improve glucose intolerance. Compared to other two TZDs, Lobe enhanced beige adipocyte formation and thermogenic gene expression in inguinal white adipose tissue (IAT) of lean mice, which would be attributable to cold-induced thermogenesis. Collectively, these comparison data suggest that Lobe could relieve insulin resistance and enhance thermogenesis at low-concentration conditions where Rosi and Pio are less effective.

• Biomedical Science Letters
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• v.14 no.3
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• pp.139-146
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• 2008

The peroxisome proliferator-activated receptor ${\gamma}$ $(PPAR{\gamma})$ plays a central role in adipogenesis and lipid storage. The $(PPAR{\gamma})$ ligands, thiazolidinediones (TZDs), enhance in vitro adipogenesis in several cell types, but the role of the TZDs on in vivo adipogenesis is still poorly understood. To investigate how $PPAR{\gamma}$ ligand troglitazone regulates adipogenesis in female mice, we examined the effects of the troglitazone on adipose tissue mass, morphological changes of adipocytes, and the expression of $PPAR{\gamma}$ target and adipocyte-specific genes in low fat diet-fed female C57BL/6 mice. Administration of troglitazone for 13 weeks did not change body and total white adipose tissue weights compared with control mice. Troglitazone treatment also did not cause a significant decrease in the average size of adipocytes in parametrial adipose tissue although it is reported to increase the number of small adipocytes in male animals. Troglitazone did not affect the mRNA expression of $PPAR{\gamma}$ and its target genes as well as adipocyte-specific genes in parametrial adipose tissue. These results suggest that $PPAR{\gamma}$ does not seem to be associated with adipogenesis in females with functioning ovaries and that its inability to induce adipogenesis may be due to sex-related factors.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.2
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• pp.349-359
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• 2020

Objective: Orchastric changes in the mammary glands are vital, especially during lactation. The secretary epithelial cells together with the supporting myoepithelial and stromal cells function cordially to secrete milk. Increase in the number of luminal epithelial cells and a decrease in adipocytes are visible during lactation, whereas the reverse happens in the involution. However, an early involution occurs if the epithelial cells transdifferentiate towards adipocytes during the lactation period. We aimed to inhibit the adipocyte transdifferentiation of luminal cells by restraining the peroxisomal proliferator-activated receptor γ (PPARγ) pathway. Methods: Linolenic acid (LA) and thiazolidinediones (TZDs) induced adipogenesis in mammary epithelial cells were conducted in monolayer, mixed culture as well as in transwell plate co-culture with mammary myoepithelial cells. Results: Co-culture with myoepithelial cells showed higher adipogenic gene expression in epithelial cells under LA+TZDs treatment. Increase in the expressions of PPARγ, CCAAT/enhancer-binding protein α and vimentin in both mRNA as well as protein levels were observed. Whereas, bisphenol A diglycidyl ether treatment blocked LA+TZDs induced adipogenesis, as it could not show a significant rise in adipose related markers. Although comparative results were found in both mixed culture and monolayer conditions, co-culture technic was found to work better than the others. Conclusion: Antagonizing PPARγ pathway in the presence of myoepithelial cells can significantly reduce the adipogenisis in epithelial cells, suggesting therapeutic inhibition of PPARγ can be considered to counter early involution or excessive adipogenesis in mammary epithelium in animals.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6863-6869
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• 2014

Objectives: Several preclinical and observational studies have shown that anti-diabetic medications (ADMs) may modify the risk of lung cancer. We performed a systematic review and meta-analysis evaluating the effect of metformin, sulfonylureas (SUs), thiazolidinediones (TZDs), and insulin on the risk of lung cancer in patients with diabetes mellitus (DM). Materials and Methods: We conducted a systematic search of Pubmed and Web of Science, up to August 20, 2013. We also searched the Conference Proceedings Citation Index (CPCI) and China National Knowledge Infrastructure (CNKI) for abstracts from major meetings. Fixed or random effect pooled measures were selected based on heterogeneity among studies, which was evaluated using Q test and the I2 of Higgins and Thompson. Meta-regression was used to explore the sources of between-study heterogeneity. Publication bias was analyzed by Begg's funnel plot and Egger's regression test. Associations were assessed by odds ratios (ORs) with 95% confidence intervals (CIs). Results: A total of 15 studies (11 cohort, 4 case-control) were included in this meta-analysis. In observational studies no significant association between metformin (n=11 studies; adjusted OR=0.99, 95%CI: 0.87-1.12), SUs (n=5 studies; adjusted OR=0.98, 95%CI: 0.79-1.22), or TZDs (n=7 studies; adjusted OR=0.92, 95%CI: 0.75-1.13), insulin (n=6 studies; adjusted OR=1.13, 95%CI: 0.79-1.62) use and risk of developing lung cancer was noted. There was considerable inherent heterogeneity between studies not explained by study design, setting, or location. Conclusions: Meta-analysis of existing studies does not support a protective or harmful association between ADMs use and risk of lung cancer in patients with DM. There was considerable heterogeneity across studies, and future, well-designed, prospective studies would be required for better understanding of any association.

• Biomedical Science Letters
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• v.12 no.2
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• pp.65-72
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• 2006

Thiazolidinediones (TZDs) are widely used antidiabetic drugs that activate the nuclear peroxisome proliferator-activated receptor ${\gamma}(PPAR{\gamma})$, and thereby improve the metabolic abnormalities linking hypertriglyceridemia to diabetes, hyperglycemia, insulin resistance, and cardiovascular disease. To determine whether the $PPAR{\gamma}$ ligand troglitazone regulates lipid metabolism with sexual dimorphism, we examined the effects of troglitazone on circulating lipids, body weight and the expression of hepatic genes responsible for lipid metabolism in both sexes of C57BL/6J mice. Compared to mice fed a low fat control diet, both sexes of mice fed a troglitazone-treated low fat diet for 14 weeks did not exhibit changes in body weight gain, serum total cholesterol, HDL-cholesterol and LDL-cholesterol levels. However, serum triglycerides were significantly reduced in both sexes of mice, although these effects were more pronounced among males. Furthermore, troglitazone regulated the expression of hepatic genes critical for lipid and lipoprotein metabolism, the magnitudes of which were much higher in males compared to females, as evidenced by results for increased acyl-CoA oxidase and decreased apolipoprotein C-III mRMA levels. These results suggest that $PPAR{\gamma}$ activator troglitazone may exert sexually dimorphic control of serum triglycerides in part through the differential activation of $PPAR{\gamma}$ in liver between male and female mice.

• Korean Journal of Animal Reproduction
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• v.26 no.4
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• pp.321-328
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• 2002

The hormone resistin is associated with type II diabetes mellitus in rodent model. Resistin impairs glucose tolerance and insulin action. A new class of anti-diabetic drugs were called thiazolidinediones (TZDs) downreguates a resistin. Resistin gene expression is induced during adipocyte differentiation and resistin polypeptide is secreted by adipocytes. But, the correlation between increased adiposity and resistin remains unknown. The objectives of this study was to clone a mouse resistin CDNA and to generate transgenic mice overexpressing mouse resistin gene. The pCMV-mus/resistin gene was prepared from previous recombinant pTargeT$^{TM}$-mus/resistin by digestion of Bgl II, and has used for microin- jection into pronuclei of one cell embryos. Mouse resistin expression was detected in transgenic F$_1$mice by RT-PCR. The transgenic mouse with resistin gene expression has heavier body weight which was measured higher level of plasma glucose than that of normal mouse. And in diet-induced experiments, in fasting group, resistin expression was higher than that of re-feeding group. This result demonstrates that the resistin gene overexpressing mice may be became to obesity and be useful as an animal disease model to be diabetes caused by insulin resistance of resistin.n.

• YAKHAK HOEJI
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• v.51 no.5
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• pp.307-312
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• 2007

Thiazolidinediones (TZDs) induce insulin sensitization through the activation of PPAR${\gamma}$. However, the undesirable effect such as weight gain was observed. The purpose of this study was to find out an herbal drug that could reduce the side effects of pioglitazone. Among herbal formula that we have searched, oryung-san (OR) inhibited the differentiation of preadipocytes and did not affect on glucose uptake in 3T3-L1 adipocytes. In vitro, glucose uptake assay and Oil Red-O staining in 3T3-L1 adipocytes were conducted. In vivo, pioglitazone (PIO, 30 mg/kg), oryung-san (OR, 300 mg/kg), or pioglitazone co-administered with oryung-san (PIO+OR) were administered orally for 7 weeks in high fat diet (HFD) fed ICR mice and measured the body weight and blood glucose level every week. PIO+OR group significantly reduced body weight gain, triglyceride, and total cholesterol compared to PIO group. In addition, PIO+OR group showed a significant reduction of plasma glucose level (72%) compared to HFD control group. Insulin levels in PIO+OR group was also markedly decreased by 85% and 41% compared to HFD control and PIO group, respectively. Diameter of white adipocytes was decreased in the PIO+OR group compared to that in PIO group. Moreover, PIO+OR group reduced expression of PPAR${\gamma}$ and SREBP1a compared to PIO group. Taken together, oryung-san can improve side effects of pioglitazone, such as weight gain and edema, and shows a synergistic effect in plasma insulin levels.