Effect of Atorvastatin on Expression of Peroxisome Proliferator-activated Receptor Beta/delta in Angiotensin II-induced Hypertrophic Myocardial Cells In Vitro.

OBJECTIVE: To explore the effect of atorvastatin on cardiac hypertrophy and to determine the potential mechanism involved. METHODS: An in vitro cardiomyocyte hypertrophy from neonatal rats was induced with angiotensin II (Ang II) stimulation. Before Ang II stimulation, the cultured rat cardiac myocytes were pretreated with atorvastatin at different concentrations (0.1, 1, and 10 µmol/L). The following parameters were evaluated: the myocyte surface area, 3H-leucine incorporation into myocytes, mRNA expressions of atrial natriuretic peptide, brain natriuretic peptide, matrix metalloproteinase 9, matrix metalloproteinase 2, and interleukin-1ß, mRNA and protein expressions of the δ/ß peroxisome proliferator-activated receptor (PPAR) subtypes. RESULTS: It was shown that atorvastatin could ameliorate Ang II-induced neonatal cardiomyocyte hypertrophy in the area of cardiomyocytes, 3H-leucine incorporation, and the expression of atrial natriuretic peptide and brain natriuretic peptide markedly. Meanwhile, atorvastatin also inhibited the augmented mRNA level of several cytokines in hypertrophic myocytes. Furthermore, the down-regulated expression of PPAR- δ/ß at both the mRNA and protein levels in hypertrophic myocytes could be significantly reversed by atorvastatin treatment. CONCLUSIONS: Atorvastatin could improve Ang II-induced cardiac hypertrophy and inhibit the expression of cytokines. Such effect might be partly achieved through activation of the PPAR-δ/ß pathway.

Protective effects of kojic acid on the periphery blood and survival of beagle dogs after exposure to a lethal dose of gamma radiation.

In previous studies, it has been shown that pretreatment with kojic acid (KA) not only increased the 30 day survival rate of mice after exposed to a lethal dose of gamma radiation but also had significant radioprotective effects on the hematopoietic system, the immune system and DNA of mice exposed to a 4 Gy sublethal dose of radiation. Furthermore, pretreatment with KA has also been shown to protect Chinese hamster ovary (CHO) cells against ionizing radiation-induced damage. In this investigation, beagle dogs were used to evaluate whether KA could also be radioprotective in a large animal model. Dogs in the group pretreated with kojic acid after whole-body exposure to a lethal dose of 3 Gy gamma radiation had a 51 day survival rate of 66.7% versus the dogs in the 3 Gy irradiation only group, which all died within 16 days of postirradiation. General vital signs (body weight or temperature) of animals in the kojic acid pretreated group reduced and increased maximally at day 14 postirradiation and then reverted to normal levels gradually. The hematopoiesis studies indicated that the white blood cells/red blood cells, hemoglobin content and hematocrit of dogs pretreated with kojic acid decreased sharply at day 23/day 21 postirradiation, and then gradually elevated. In addition, the DNA content of dogs pretreated with KA were significantly increased compared with that of dogs in the irradiation group at day 4 postirradiation and the number of micronuclei in the group pretreated with kojic acid declined sharply compared with that of the irradiation only group. KA appears to possess marked protective effects from radiation-induced damage and therefore, may be a promising novel radioprotective agent.

Kojic acid protects C57BL/6 mice from gamma-irradiation induced damage.

The radioprotective effects of a single administration of kojic acid (KA) against ionizing radiation were evaluated via assessment of 30-day survival and alterations of peripheral blood parameters of adult C57BL/6 male mice. The 30-day survival rate of mice pretreated with KA (75 or 300 mg/kg body weight, KA75 or KA300) subcutaneously 27 h prior to a lethal dose (8 Gy, 153.52 cGy/min) of gamma irradiation was higher than that of mice irradiated alone (40% or 60% vs 0%). It was observed that the white blood cell (WBC) count/the red blood cell (RBC) count, haemoglobin content, haematocrit and platelet count of mice with or without KA pretreatment as exposed to a sub-lethal dose (4 Gy, 148.14 cGy/min) of gamma irradiation decreased maximally at day 4/day 8 post-irradiation. Although the initial WBC values were low in KA300 or WR-2721 (amifostine) groups, they significantly recovered to normal at day 19, whereas in the control group they did not. The results from the cytotoxicity and cell viability assays demonstrated that KA could highly protect Chinese hamster ovary (CHO) cells against ionizing radiation with low toxicity. In summary, KA provides marked radioprotective effects both in vivo and in vitro.

GRK 2 level in peripheral blood lymphocytes of elderly patients with acute myocardial infarction.

OBJECTIVE: To investigate the G protein-coupled receptor kinase 2 (GRK 2) level in peripheral blood lymphocytes with cardiac function in elderly patients with acute myocardial infarction. METHODS: This study enrolled 40 patients with acute ST-segment elevation myocardial infarction (STEMI) and 40 patients with unstable angina. All patients were 65 years or older. Cardiac function was evaluated by echocardiography, and the GRK 2 level in peripheral blood lymphocytes was measured. Patients with STEMI were followed up for 2 years. RESULTS: The GRK 2 level in peripheral blood lymphocytes was significantly higher in patients with STEMI than in patients with unstable angina, and was negatively correlated with left ventricular ejection fraction, cardiac output, stroke volume, and left ventricular fractional shortening. The GRK 2 level was significantly elevated in some patients with acute STEMI and poor cardiac function. CONCLUSIONS: Increased GRK 2 level in patients with acute STEMI may contribute to poor myocardial systolic function and myocardial remodeling. Measurement of the GRK 2 level in peripheral blood lymphocytes may assist in the evaluation of cardiac function and myocardial remodeling in elderly patients with acute STEMI.

[Lymphocyte GRK2 expression of the very elderly with chronic heart failure].

OBJECTIVE: To explore the correlation of lymphocyte G protein-coupled receptor kinases 2 (GRK2) expression of the very elderly with chronic heart failure (HF) and heart ejection fraction (EF). METHODS: 16 elderly patients with chronic heart failure were divided into 2 groups as following: EF < 45% (n=7), EF > or = 45% (n=9); and health elderly as control (n=8). Lymphocytes were obtained from blood, reverse transcription polymerase chain reaction were used to measure GRK2 mRNA levels. RESULTS: Lymphocyte GRK2 mRNA levels of EF < 45% group were higher than that of EF > 45% group, which were greater than that of control. CONCLUSION: Elevation of lymphocyte GRK2 levels in HF is associated with heart EF, lymphocytes may provide a surrogate for monitoring cardiac GRK2 in human HF.

[Effect of metoprolol on the expression of GRK2 in lymphocyte of advanced elderly patients with chronic heart failure].

OBJECTIVE: To investigate the effect of metoprolol on the expression of G protein-coupled receptor kinases 2 (GRK2) in lymphocyte of advanced elderly patients with chronic heart failure. METHODS: 32 elderly patients with chronic heart failure were divided into control group and metoprolol group, 16 each. Conventional therapy was used in the control group, conventional therapy plua metoprolol was used in metoprolol group. The treatment courses were 8 weeks in both groups. RESULTS: Left ventricular end-diastolic diameter and left ventricular ejection fraction were not different between the two groups. Lymphocyte GRK2 mRNA level in metoprolol group was lower than that in control group. CONCLUSION: Metoprolol can inhibit the expression of GRK2 in lymphocyte of advanced elderly patients with chronic heart failure.

[Involvement of leukotrine B4 receptors in the inflammatory responses and immunological regulation in vitro].

AIM: BLT1 and BLT2 were both recently cloned and identified as two subtypes of leukotrine B4 (LTB4) receptors. With the usage of U-75302 and LY255283, the specific antagonists of BLT1 and BLT2 respectively, the involvement of BLT1 and BLT2 in the inflammatory and immunological responses was in vitro explored. METHODS: (1) To investigate inhibition of U-75302 and LY255283 on the proliferation of rat synovial cells, 3H-TdR incorporation into the cells was quantified. (2) Flow cytometric assay for interferon-gamma (IFN-gamma) and interleukine 4 (IL-4) profiles in CD4+ T lymphocytes from rat spleen was carried out to determine the ratio of Th1/Th2. RESULTS: (1) For inhibition on rat synovial cells proliferation, U-75302 exerted its effect only at a high concentration of 10 micromol/L and LY255283 at the concentrations of 10 micromol/L-10 micromol/L. (2) Both U-75302 and LY255283 could elevate the percentage of Th2, but could not influence that of Th1. CONCLUSION: BLT1 and BLT2 were involved in the synovial cells proliferation change the ratio of Th1/Th2. Their meaning served as targets for prevention and treatment of infectious diseases should be emphasized.

Peroxisome proliferator-activated receptor beta/delta activation improves angiotensin II-induced cardiac hypertrophy in vitro.

Agonists of the peroxisome proliferator-activated receptor alpha (PPARalpha) and gamma (gamma) exert anti-proliferative and anti-inflammatory effects that led to the testing of these drugs in experimental cardiac hypertrophy. However, the effect of PPAR beta/delta (beta/delta) agonists in hypertrophy is not yet known. In this paper, an experiment was conducted to explore whether PPARbeta/delta activation has an effect on cardiac hypertrophy. An in vitro cardiomyocyte hypertrophy from neonatal rats was induced with Angiotensin II (Ang II1micromol x L(-1)) stimulation. For the examination of PPAR beta/delta effect, the cultured rat cardiac myocytes were pretreated with GW0742 (10 micromol.L(-1)), an agonist of PPARbeta/delta, for 48h before Ang II stimulation. The following parameters in the cultured cells were determined: surface areas of myocytes were measured by the NIH Image Software; (3)H-leucine incorporation into myocytes was counted by liquid scintillometer; mRNA expression of PPARbeta/delta, ANP, BNP, MMP9, MMP2, and IL-1beta was detected by RT-PCR; PPARbeta/delta protein expression was evaluated with immunofluorescence staining; GW0742 could ameliorate Ang II-induced cardiomyocyte hypertrophy, as indicated by its inhibitory effects on the surface area of myocytes, and ANP and BNP mRNA expressions in myocytes and (3)H-leucine incorporation into myocytes. Meanwhile, GW0742 pretreatment exerted inhibition on mRNA expression augmentation of such cytokines as MMP9, MMP2, and IL-1beta in hypertrophic myocytes. In addition, the down-regulated expression of PPARbeta/delta mRNA and protein in hypertrophic myocytes was also significantly reversed by GW0742. We demonstrate for the first time that GW0742 exerts a beneficial effect on Ang II-induced cardiac hypertrophy and the relation to inflammation response.

Inhibition of plasminogen activator inhibitor type-1 expression in HepG2 cells by fenofibrate may be associated with Smad signaling.

BACKGROUND: We investigated the molecular mechanism underlying the effect of fenofibrate on expression of plasminogen activator inhibitor type-1 (PAI-1) in HepG2 cells. METHODS: Luciferase reporter gene plasmids containing four sequentially truncated fragments of the PAI-1 promoter region (-804 to +17) were constructed and plasmids carrying constructs of Smad binding element (SBE)-site-directed deletions in the PAI-1 promoter were also generated and then transfected to HepG2 cells prior to fenofibrate treatment. Smad3 and Smad4 protein levels were measured by Western blotting. RESULTS: The decreased expression of PAI-1 mRNA and protein was detected in HepG2 cells after exposure to fenofibrate. PAI-1 transcription activities were also down-regulated following exposure to fenofibrate in HepG2 cells when they were transfected with the luciferase reporter gene plasmid containing a full-length of PAI-1 promoter. However, with the truncation of PAI-1 promoter, the inhibitory effect of fenofibrate on the transcription activity of PAI-1 gradually diminished. Furthermore, the transcription activity of PAI-1 was significantly up-regulated by fenofibrate in HepG2 cells when they were transfected with plasmids of the SBEs-deleted PAI-1 promoter. The expression of both Smad3 and Smad4 proteins was suppressed by fenofibrate. CONCLUSION: Fenofibrate exerts its inhibitory effect on PAI-1 transcription in HepG2 cells presumably involving Smad signaling pathways.

[Subcellular localization and tissues expression profile of hGPCRc: an orphan G protein-coupled receptor].

As a member of orphan G protein-coupled receptors (oGPCRs), hGPCRc was cloned from human colon tissue and analyzed by bioinformatic softwares. It was showed that the corresponding amino acids of hGPCRc formed seven-transmembrane domains as the key characteristic of GPCRs. Then, the recombinant GFP-hGPCRc was constructed by fussing hGPCRc into pEGFP-N1 carrying green fluorescent protein (GFP) gene, and CHO-K1 cells were subsequently transfected with the GFP-hGPCRc or pEGFP-N1. The green fluorescence protein expression in the two different transfected cells was observed under the laser scanning confocal microscopy (LSCM). It was showed that green fluorescence protein was distributed in the whole bodies of the cells transfected with pEGFP-N1, but mainly distributed on the plasma membrane and cytoplasm membrane transfected with GFP-hGPCRc. Thus, the localization on the membrane of hGPCRc was accorded with the predication by bioinformatic analysis. The expression analysis of hGPCRc by RT-PCR indicated that hGPCRc was abundantly expressed in heart, kidney, cerebel and colon etc., but absent in liver, cerebra, small intestine and muscle etc. The expressing profile of hGPCRc could provide some useful clues to understanding its effects on embryonic development and physiological functions.