OBJECTIVETo investigate the effects of rapamycin on cholesterol homeostasis and secretory function of 3T3-L1 cells.

METHODSThe in vitro cultured 3T3-L1 cells (preadipocytes) were divided into control group, rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group. Intracellular cholesterol level was measured by oil red O staining and high performance liquid chromatography. The secretion levels of leptin and adiponectin were assayed by enzyme-linked immunosorbent assay. The mRNA and protein expressions of peroxisome proliferator-activated receptor (PPARgamma) were assayed by quantitative real-time polymerase chain reaction and Western blot.

RESULTSOil red O staining showed rapamycin down-regulated 3T3-L1 cells differentiation and lipid accumulation. Quantitative measurement of cholesterol with high performance liquid chromatography showed that the concentrations of free cholesterol in rapamycin treatment groups had a significant reduction. The concentrations of free cholesterol in the control group, rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group were (12.89 +/- 0.16), (9.84 +/- 0.45), (9.39 +/- 0.46), and (8.61 +/- 0.34) mg/ml, respectively (P < 0.05), and the concentrations of total cholesterol were (12.91 +/- 0.50), (9.94 +/- 0.96), (10.45 +/- 2.51), and (9.53 +/- 0.63) mg/ml, respectively. The leptin concentrations in the control group, rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group were (19.02 +/- 0.52), (16.98 +/- 0.11), (15.62 +/- 0.01), and (13.84 +/- 0.66) ng/ml, respectively. The mRNA expressions of PPARgamma in the rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group were significantly lower than that in control group (P < 0.05). The protein expressions of PPARgamma in the rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group were 80%, 74%, and 61% of that in control group (P < 0.05). After the cells were treated with rapamycin 100 nmol/L, PPARgamma blocking agent GW9662 10 micromol/L, and PPARgamma agonist troglitazone 10 micromol/L, respectively, for 96 hours, the mRNA expression of PPARgamma was (0.60 +/- 0.14), (0.67 +/- 0.03), and (1.30 +/- 0.14) of that in control group (P < 0.05). The protein expression showed a similar trend with mRNA expression (P < 0.05). After the cells were treated with rapamycin 100 nmol/L, PPARgamma blocking agent GW9662 10 micromol/L, and PPARgamma agonist troglitazone 10 micromol/L, respectively, for 96 hours, the expression of leptin in the control group, rapamycin 50 nmol/L group, rapamycin 100 nmol/L group, and rapamycin 200 nmol/L group was (19.02 +/- 0.52), (15.62 +/- 0.10), and (14.45 +/- 1.01) and (18.07 +/- 0.66) ng/ml, respectively (P < 0.05 compared with the control group).

CONCLUSIONSBy downregulating the expression of PPARgamma, rapamycin can decrease cholesterol accumulation in 3T3-L1 cells and inhibit its leptin-secreting capability. This finding may provide a possible explanation for rapamycin-induced hyperlipidemia in clinical practice.

3T3-L1 Cells ; Adipocytes ; drug effects ; metabolism ; Animals ; Cholesterol ; metabolism ; Leptin ; metabolism ; Mice ; PPAR gamma ; genetics ; metabolism ; Sirolimus ; pharmacology

OBJECTIVEThis study was to investigate the effect of pioglitazone on apoptotic cardiomyocytes with the model of ischemia-reperfusion at rat heart in vivo.

METHODSSprague-Dawley rats were randomly divided into two groups. One was 30 min reperfusion group, which was subdivided into sham (n = 5), model (vehicle, n = 6) and pioglitazone 3 mg/kg (n = 7) with 30 min ischemia followed by 30 min reperfusion to detect the area of myocardial infarction (MI). Another was 2 h reperfusion group, which was further subdivided into sham (n = 5), model (vehicle, n = 6), and pioglitazone 0.3 mg/kg (n = 6), 1 mg/kg (n = 7) and 3 mg/kg (n = 6). Apart from the sham, pioglitazone and vehicle were administered intravenously 30 min before occlusion. Then hearts were excised, paraffined and cut into 4 microm thick. Immunohistochemistry, in situ hybridization, TUNEL and DNA agarose gel electrophoresis were performed to detect the expression of Bax, Bcl-2, Caspase-3 and PPARgamma protein and PPARgamma mRNA.

RESULTS(1) Compared with model, nec/aar of pioglitazone decreased by 28% (P < 0.01). The nec/lv ratio reduced by 32% (P < 0.01). (2) In a dose-dependent manner, the expressions of Bax and Caspase-3 were depressed, while the expression of Bcl-2, PPARgamma protein and PPARgamma mRNA were enhanced by pioglitazone. (3) The apoptotic index of subgroups injected pioglitazone reduced significantly by TUNEL compared with model (P < 0.05). Agarose gel electrophoresis demonstrated that DNA ladder existed in model, pioglitazone 0.3 mg/kg and pioglitazone 1 mg/kg, but not pioglitazone 3 mg/kg.

CONCLUSIONSPioglitazone could protect the heart from I/R injury evidenced by the improvement in the expression of PPARgamma at the levels of protein and mRNA after pioglitazone administrated, and by the decrease in the apoptotic cardiomyocytes.

Animals ; Apoptosis ; drug effects ; Male ; Myocardial Reperfusion Injury ; metabolism ; Myocardium ; metabolism ; Myocytes, Cardiac ; cytology ; drug effects ; metabolism ; PPAR gamma ; metabolism ; Rats ; Rats, Sprague-Dawley ; Thiazolidinediones ; pharmacology

In gliomas, the canonical Wingless/Int (WNT)/β-catenin pathway is increased while peroxisome proliferator-activated receptor gamma (PPAR-γ) is downregulated. The two systems act in an opposite manner. This review focuses on the interplay between WNT/β-catenin signaling and PPAR-γ and their metabolic implications as potential therapeutic target in gliomas. Activation of the WNT/β-catenin pathway stimulates the transcription of genes involved in proliferation, invasion, nucleotide synthesis, tumor growth, and angiogenesis. Activation of PPAR-γ agonists inhibits various signaling pathways such as the JAK/STAT, WNT/β-catenin, and PI3K/Akt pathways, which reduces tumor growth, cell proliferation, cell invasiveness, and angiogenesis. Nonsteroidal anti-inflammatory drugs, curcumin, antipsychotic drugs, adiponectin, and sulforaphane downregulate the WNT/β-catenin pathway through the upregulation of PPAR-γ and thus appear to provide an interesting therapeutic approach for gliomas. Temozolomide (TMZ) is an antiangiogenic agent. The downstream action of this opposite interplay may explain the TMZ-resistance often reported in gliomas.
Animals ; Brain Neoplasms ; metabolism ; therapy ; Dacarbazine ; analogs & derivatives ; pharmacology ; Down-Regulation ; drug effects ; Glioma ; metabolism ; therapy ; Humans ; PPAR gamma ; metabolism ; Temozolomide ; Wnt Signaling Pathway ; drug effects ; physiology

OBJECTIVETo investigate the protective effects of glitazones on islet beta cells and PPAR gamma dependence of such effects.

METHODSIL-1beta and IFN-gamma were used to treat NIT-1 cells, a beta cell line, to induce beta cell damage. The cells were pretreated with rosiglitazone and pioglitazone at different concentrations to study the protective effects of these drugs. The cell apoptosis rate was determined with Annexin V-FITC by flow cytometry, and the insulin secretion capacity of the cells was assessed with ELISA. GW9662 and PPARgamma-SiRNA were used to specifically inhibit PPAR to investigate the PPAR gamma-dependent mechanisms.

RESULTSRosiglitazone and pioglitazone at 10 micromol/L could significantly decrease the apoptosis of beta cells induced by the cytokines (apoptotic rates of 13.99% and 16.67% vs 51.33%, P<0.01). Rosiglitazone at 10 micromol/L and pioglitazone at 20 micromol/L were less effective than 10 micromol/L rosiglitazone and pioglitazone. The insulin secretion of the cytokine-treated cells decreased from 8.5-/+0.6 ng/ml of the control group to 3.6-/+0.5 ng/ml, while rosiglitazone and pioglitazone could increase the insulin secretion to 6.8-/+0.7 ng/ml and 5.9-/+0.9 ng/ml, respectively. When PPAR gamma was specifically inhibited by GW9662 and PPARgamma-SiRNA, the protective effects of rosiglitazone and pioglitazone were almost undetectable, and the apoptotic rate increased and insulin secretion decreased to the level of the cytokine-treated cells.

CONCLUSIONGlitazones can protect beta cells from apoptosis and impairment of insulin secretion function resulting from the cytotoxic cytokines via a PPAR gamma-dependent mechanism.

Animals ; Apoptosis ; drug effects ; Cell Line ; Insulin ; secretion ; Insulin-Secreting Cells ; drug effects ; metabolism ; secretion ; Interferon-gamma ; adverse effects ; Interleukin-1beta ; adverse effects ; Islets of Langerhans ; metabolism ; Mice ; Mice, Transgenic ; PPAR gamma ; metabolism ; Thiazolidinediones ; pharmacology

OBJECTIVETo investigate the effects of Artesunate(Art) on the LX-2 cell.

METHODSThe cultured hepatic stellate cells were divided into control group and Art-treated groups with 250,350,450 µmol/L. The rate of cellular proliferation was detected by MIT assay, the content of ceramide (Cer)was determined by HPLC method, the content of hydroxyproline (Hyp) was determined by enzyme digestion method, the expressions of PPAR-&gamma;, p53 and Caspase 3 were detected by Western blot.

RESULTSCompared with control group, IX-2 treated with Art were inhibited in a concentration-dependent manner(P < 0.01). Art could significantly increase the content of cerarnide in LX-2 ( P <0.01), and the content of Hyp was significantly decreased (P <0.05, P <0.01). The expressions of PPAR-&gamma;, p53 and Caspase 3 were increased compared with that of control group(P < 0.01).

CONCLUSIONArtesunate could inhibit the proliferation and induce apoptosis of hepatic stellate cells through upregulating ceramide.

Apoptosis ; Artemisinins ; pharmacology ; Caspase 3 ; metabolism ; Cell Line ; Cell Proliferation ; Ceramides ; metabolism ; Hepatic Stellate Cells ; drug effects ; Humans ; Hydroxyproline ; metabolism ; Liver Cirrhosis ; PPAR gamma ; metabolism

The effects of DK2, a peroxisome proliferator-activated receptor &gamma; agonist, on cultured human pterygium fibroblasts (HPFs) in virto were studied. The HPFs were incubated with 0-200 μmol/L DK2 for 12-72 h. The MTT method was used to assay the bio-activity of DK2 at different doses and time. The cytotoxic effect of DK2 was measured by LDH release assay. The cell cycle distribution and apoptosis were flow cytometrically detected. The expression of proliferating cell nuclear antigen (PCNA) in each group was detected by real-time PCR (RT-PCR) and Western blotting. The results showed that administration of 1-75 μmol/L DK2 for 12-72 h could significantly inhibit HPF proliferation in a dose- and time-dependent manner. DK2-treated cells did not release significant amount of LDH as compared with rosiglitazone-treated cells. After treatment with DK2 at concentrations of 15, 25 μmol/L for 24 h, the number of HPFs in G(0)/G(1) phase was significantly increased while that in S phase was significantly decreased (P<0.05), leading to arrest at G(0)/G(1) phase. The apoptosis rates of HPF cells in drug-treated groups were significantly higher than the rate of control group (P<0.05). At the dosage range between 15-25 μmol/L, DK2 could inhibit the expression of PCNA mRNA and protein in HPFs in a dose-dependent fashion (P<0.05). It was concluded that PPAR&gamma; agonist can significantly inhibit HPF proliferation, resulting in the arrest at G(0)/G(1) phase, induce the apoptosis of HPFs, and suppress the synthesis of PCNA, in dose- and time-dependent manners.
Adult ; Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Female ; Fibroblasts ; pathology ; Humans ; Middle Aged ; PPAR gamma ; agonists ; Proliferating Cell Nuclear Antigen ; metabolism ; Pterygium ; pathology

Animals ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Liver ; drug effects ; metabolism ; Liver Cirrhosis, Experimental ; metabolism ; Male ; PPAR gamma ; metabolism ; Rats ; Rats, Wistar

OBJECTIVETo investigate the effects of GW4064, a farnesoid X receptor (FXR) agonist, on adiponectin and its receptors during the differentiation of 3T3-L1 preadipocytes and on adiponectin receptors in HepG2 cells.

METHODSThe mRNA expressions of FXR, PPAR&gamma;2, adiponectin, AdipoR1, and AdipoR2 and the protein levels of adiponectin on days 0, 2, 4, 6, and 8 during the differentiation of 3T3-L1 preadipocytes treated with GW4064 were detected by fluorescent real-time PCR and ELISA, respectively. The mRNA expressions of AdipoR1 and AdipoR2 in HepG2 cells were also examined at 0, 12, 24, and 48 h after GW4064 treatment.

RESULTSThe mRNA expressions of FXR, PPAR&gamma;2, adiponectin, and AdipoR2 in 3T3-L1 preadipocytes and AdipoR2 in HepG2 cells treated with GW4064 was significantly increased compared with the control group (all P<0.05). The protein level of adiponectin was also significantly increased after GW4064 treatment. The expression of AdipoR1 in either 3T3-L1 preadipocytes or HepG2 cells showed no significant changes after GW4064 treatment.

CONCLUSIONGW4064 can up-regulate the expressions of FXR, PPAR&gamma;2, adiponectin, AdipoR2 in 3T3-L1 preadipocytes and AdipoR2 in HepG2 cells. As adiponectin and its receptors are two important factors in the treatment of non-alcoholic fatty liver disease, FXR agonist may potentially produce therapeutic effect on non-alcoholic fatty liver disease and can regulate adipocytes via up-regulating PPAR&gamma; during adipocyte differentiation.

3T3-L1 Cells ; Adiponectin ; metabolism ; Animals ; Cell Differentiation ; drug effects ; Hep G2 Cells ; Humans ; Isoxazoles ; pharmacology ; Mice ; PPAR gamma ; metabolism ; Receptors, Adiponectin ; metabolism ; Receptors, Cytoplasmic and Nuclear ; agonists

OBJECTIVETo investigate the effect of PPARgamma1 gene overexpression on caveolin-1 mRNA and protein expressions in a murine macrophage cell line Raw264.7.

METHODSReplication-deficient recombinant adenovirus expression vector of PPARgamma1 was constructed using the AdEasy system. Raw264.7 cells were randomly treated as follows: P group (PPARgamma1 gene overexpression), T group (Troglitazone 40 micromol/L in DMSO), PT group (PPARgamma1 gene overexpression and Troglitazone) and control group. Changes of PPARgamma1 and caveolin-1 at mRNA and protein levels were investigated.

RESULTSCaveolin-1 expression can be detected by RT-PCR in Raw264.7, by immunocytochemistry method in cell and nuclear membrane but not by immunoblotting at protein level. Caveolin-1 expression at mRNA and protein levels in Raw264.7 were significantly higher in P, T and PT groups compared to control group and the expression was also significantly higher in PT group than that in P group and T group (P < 0.05). PPARgamma expression was significantly increased in PT group and P group where remained unchanged in T group compared to control group.

CONCLUSIONPPARgamma1 overexpression can upregulate caveolin-1 expression in macrophages. Troglitazone upregulated caveolin-1 expression in the absence of increased PPARgamma1 expressions at mRNA and protein levels.

Adenoviridae ; genetics ; Animals ; Caveolin 1 ; metabolism ; Cell Line ; Chromans ; pharmacology ; Gene Expression ; Macrophages ; drug effects ; metabolism ; Mice ; PPAR gamma ; genetics ; RNA, Messenger ; metabolism ; Thiazolidinediones ; pharmacology

OBJECTIVETo study the effect and mechanism of berberine (BER) on the proliferation and differentiation of adipocytes.

METHODSThe proliferation of 3T3-L1 pre-adipocytes was detected by XTT method. Lipid droplets accumulated in the cytoplasm of adipocytes in the differentiating process were observed by oil red O staining and quantified by colorimetry. The expressions of peroxisome proliferation activated receptor gamma (PPARgamma), CAAT/enhancer binding protein alpha (C/EBPalpha) mRNA and protein were detected by Real-time PCR and Western blotting respectively.

RESULTSIntervention with BER in concentration below 10 micromol/L for 24 h showed insignificant effect on the proliferation of adipocytes, as compared with that in the control group (P > 0.05); but that in concentrations 20, 40 and 80 micromol/L revealed significant suppressive effect; that in different concentrations acting for 48 h and 72 h could affect the proliferation and the effect displayed a dose-dependent manner, i. e. the higher the concentration of BER, the more apparent the suppression, showing significant difference as compared with those in the control group (P <0.05 or P <0.01). The pre-adipocyte treated with 10 micromol/L BER showed that the lipid droplets in the cytoplasm significantly lessened, so did the expression of differentiation related factor PPAR gamma mRNA as well as the expressions of C/EBPalpha mRNA and protein, as compared with those in the blank control group and the group intervened with rosiglitazone, the difference was significant (P < 0.05 or P < 0.01).

CONCLUSIONSBER can suppress the proliferation and differentiation of 3T3-L1 pre-adipocytes, reduce the accumulation of lipid drops in the adipocyte differentiating process, which may be associated with its effects in decreasing the expressions of adipocyte differentiation related gene PPARgamma, C/EBPalpha mRNA and protein. The study provides a basis for applying BER on the prevention and treatment of such metabolic related diseases as obesity.

3T3-L1 Cells ; Adipocytes ; cytology ; drug effects ; metabolism ; Animals ; Berberine ; pharmacology ; CCAAT-Enhancer-Binding Protein-alpha ; genetics ; metabolism ; Cell Proliferation ; drug effects ; Gene Expression ; drug effects ; Mice ; PPAR gamma ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism