Assessment of toxicological effects of mancozeb in male rats after chronic exposure

Mancozeb, an ethylenebisdithiocarbamate fungicide was administered orally to male rats at doses 0, 500, 1000 and 1500 mg/kg/day for 90, 180 and 360 days produced dose dependent signs of poisoning, loss in body weight gain and mortality. However the signs of toxicity and mortality were more pronounced initially at 0-90 days as compared to 90-360 days of treatment period. A significant increase in the relative weight of liver and slight decrease in the kidney weight were observed in animals exposed to mancozeb (1000 and 1500 mg/kg/day) for 180 and 360 days associated with pathomorphological changes in liver, brain and kidney. Mancozeb has produced significant enzymatic changes in the activities of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and acetylcholinesterase (AChE) throughout the period of study in a dose dependent manner. The alterations in the activity of enzymes associated with pathomorphological changes suggest that the chronic exposure of mancozeb produced significant toxicological effects in rats.     

Dimethylthiourea protects against mitochondrial oxidative damage induced by cisplatin in liver of rats

Cisplatin is one of the most effective chemotherapeutic agents. However, at higher doses liver injury may occur. The purpose of this study was to explore whether the hydroxyl radical scavenger dimethylthiourea (DMTU) protects against cisplatin-induced oxidative damage in vivo and to define the mitochondrial pathways involved in cytoprotection. Adult male Wistar rats (200–220 g) were divided into four groups of eight animals each. The control group was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml/100 g body weight). The DMTU group was given only DMTU (500 mg/kg body weight, i.p), followed by 125 mg/kg body weight, i.p. (twice a day) until sacrifice. The cisplatin group was given a single injection of cisplatin (10 mg/kg body weight, i.p.). The DMTU + cisplatin group was given DMTU (500 mg/kg body weight, i.p.), just before the cisplatin injection (10 mg/kg body weight, i.p.), followed by injections of DMTU (125 mg/kg body weight, i.p.) twice a day until sacrifice (72 h after the treatment). DMTU did not present any direct effect on mitochondria and substantially inhibited cisplatin-induced mitochondrial damage in liver, therefore preventing elevation of AST and ALT serum levels. DMTU protected against (a) decreased hepatic ATP levels; (b) lipid peroxidation; (c) cardiolipin oxidation; (d) sulfhydryl protein oxidation; (e) mitochondrial membrane rigidification; (f) GSH oxidation; (g) NADPH oxidation; (h) apoptosis. Results suggest that antioxidants, particularly hydroxyl radical scavengers, protect liver mitochondria against cisplatin-induced oxidative damage. Several mitochondrial changes were delineated and proposed as interesting targets for cytoprotective strategy.     

Effect of alcohol and kolanut interaction on brain sodium pump activity in Wistar Albino rats.

Effect of alcohol-kolanut interaction on Sodium Pump activity in wistar albino rats was studied. Thirty wistar albino rats were divided into six groups of five (5) rats per group and used for the study. The control group (1) received via oral route a placebo (4ml of distilled water). Groups 2 to 6 were treated for a period of 21 days, with (10% v/v) of alcohol (group 2), 50mg/kg body weight of kolanut (group 3), 50 mg/kg body weight of caffeine (group 4), 4ml of 10% v/v of alcohol and 50 mg/kg body weight kolanut (group 5), 4ml of 10% v/v of alcohol and 50 mg/kg body weight of caffeine in 4.0ml of the vehicle via gastric intubation respectively. A day after the final exposure, the brain of each rat was harvested and processed to examine several biochemical parameters, i.e., total ATpase, ouabain-insensitive ATpase, ouabain sensitive ATpase (Na(+)-K(+)ATPase), non-enzymatic breakdown of ATP and inorganic phosphate (Pi) released. The results showed that the essential enzyme of the brain responsible for neuronal function, Na(+)-K(+)ATPase, was inhibited by alcohol-kolanut co-administration relative to control, resulting in a decrease in Na(+)-K(+)ATPase activity, ATP production, ion transport and action potential, leading to loss of neuronal activities.     

Improving effect of ethyl eicosapentanoate on statin-induced rhabdomyolysis in Eisai hyperbilirubinemic rats

The effect of ethyl eicosapentanoate (EPA-E) on statin-induced rhabdomyolysis was investigated by co-administration of EPA-E and pravastatin (PV), as a typical statin, to Eisai hyperbilirubinemic rats (EHBR). It was confirmed that the plasma PV concentration was not affected by simultaneous administration of EPA-E, and there was no cumulative increase of PV during prolonged co-administration of EPA-E and PV. Muscular degeneration was prominent (incidence 5/5; average grade 3.5 (range 2-4)) in EHBR treated with PV alone at 200 mg/kg/day for 14 days, but co-administration of EPA-E at doses of 100, 300, and 1000 mg/kg/day decreased the average grades to 1.4 (range 0.3-3.0), 0.5 (0.2-1.0), and 0.6 (0.0-1.7), respectively. Creatine phosphokinase (CPK) and myoglobin levels in plasma were well correlated with the grade of skeletal muscle degeneration. Thus, EPA-E appears to reduce the severity of statin-induced rhabdomyolysis.     

beta-adrenergic responsiveness of rats treated chronically with isoproterenol

The effect of chronic administration of isoproterenol on isoproterenol-induced thirst and isoproterenol-induced changes in heart rate and selected organ weights of male rats was studied. Administration of 25 micrograms isoproterenol/kg, s.c., in saline daily for 10 days was accompanied by a significant attenuation of the characteristic increase in water intake following a challenging dose of isoproterenol (25 micrograms/kg, s.c.) on the 11th day. Administration of 25 micrograms isoproterenol/kg, s.c., every 2nd, 3rd or 4th day for 10 days was without significant effect on water intake following isoproterenol (25 micrograms/kg, s.c.) on the 11th day. Administration of 25 micrograms isoproterenol/kg, s.c., every day for 10 days led to a slight increase in cardiac responsiveness to a challenging dose of isoproterenol (25 micrograms/kg) on the 11th day. Chronic treatment with this low dose of isoproterenol for 10 days was also accompanied by a significant increase in the ratio of heart weight to body weight but no significant changes in the ratio of kidney, adrenal, thyroid, spleen, or interscapular brown fat to body weight. Thus, daily administration of the beta-adrenergic agonist isoproterenol for 10 days can alter beta-adrenergic responsiveness in the rat with beta 1 (heart rate) and beta 2 (thirst) mediated responses showing opposite effects. In addition, the results suggest that tests of beta-adrenergic responsiveness must be assessed in terms of the frequency of administration of the agonist.     

L-α-Aminoadipate Inhibits Kynurenate Synthesis in Rat Brain Hippocampus and Tissue Culture

Intracerebral administration of L--aminoadipic acid (L-AAA) at 500 mg/kg body weight to rats caused a complex behavioral change with sporadic wet-dog shakes. Animals developed severe limbic seizures between 1 and 6 h after L-AAA injection, characterized by generalized convulsions. Twenty days after L-AAA injection kynurenine aminotransferase (KAT) activity measured in hippocampal brain tissue slices prepared with a McIlwain chopper at 30 m showed a significant 43% decrease. Subcutaneous injection of kynurenine at 500 mg/kg showed a 63% increase in KAT activity twenty days later. This increase was offset by a concomitant administration of 500 mg/kg L-AAA stereotaxically on day one. In astrocyte culture kynurenic acid synthesis is inhibited by L-AAA and L-pipecolic acid. The possible involvement of kynurenic acid in the modulation of neuronal degeneration is discussed.     

An antioxidant treatment potentially protects myocardial energy metabolism by regulating uncoupling protein 2 expression in a chronic beta-adrenergic stimulation rat model

Excessive beta-adrenergic stimulation causes cardiac toxicity, which also contributes to cardiac oxidative stress. Although uncoupling protein 2 (UCP2), a member of the mitochondrial inner membrane carrier family, can regulate energy efficiency and oxidative stress in mitochondria, little data exist regarding interactions between UCP2 expression and beta-adrenergic stimulation induced cardiac oxidative damage. We investigated whether chronic beta-adrenergic stimulation induces myocardial energy metabolism abnormality via oxidative stress, including any role of UCP2. We also examined whether 3-methyl-1-phenyl-2-pyrazolin-5-one (MIC-186; edaravone), a potent free radical scavenger, has cardioprotective effects against beta-adrenergic stimulation. Male Sprague-Dawley rats received isoproterenol (1.2 mg/kg/day) subcutaneously or/and edaravone (30 mg/kg/day) orally. Isoproterenol increased the heart/body weight ratio, accompanied by an increase in the level of myocardial thiobarbituric acid reactive substances (TBARS) and a decreased phosphocreatine (PCr) to adenosine triphosphate (ATP) ratio. Isoproterenol also markedly increased expressions of UCP2 mRNA (1.74 fold vs. non-isoproterenol) and protein (1.93 fold vs. non-isoproterenol). Edaravone had no apparent effect in hypertrophic responses, but significantly prevented both increases in TBARS and decreases in the PCr/ATP ratio. Edaravone also prevented increases in UCP2 mRNA (0.76 fold vs. isoproterenol) and protein (0.62 fold vs. isoproterenol) expressions against isoproterenol administration. Our results suggest that chronic beta-adrenergic stimulation induces myocardial energy inefficiency via excessive oxidative stress. The antioxidant effect of edaravone has potential to improve energy metabolism abnormalities against beta-adrenergic stimulation. Adequate regulation of UCP2 expression through artificial reduction of oxidative stress may play an important role in protection of the myocardial energy metabolism.     

一种高尿酸血症大鼠模型诱导方法的改良和效果评价研究

目的: 探索短期内诱导高尿酸血症大鼠模型的有效方法,并对模型效果进行评价。方法: 雄性SD大鼠随机分为对照组(CT组,6只)和5个模型组(M1-M5组),每组8只;M1组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg 2次灌胃,于模型诱导的第7日1次性腹腔注射氧嗪酸钾300 mg/kg)、M2组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃2次,于模型诱导第1、3、7日每天腹腔注射1次氧嗪酸钾300 mg/kg)、M3组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M4组(每天酵母膏20 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M5组(每天酵母膏30 g/kg+腺嘌呤100 mg/kg灌胃2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、CT组(5个模型组按相同的时间、体重计算等体积灌胃和腹腔注射生理盐水),造模7 d;分别在造模结束时和2周后采集24 h尿样和血样检测尿酸、肌酐水平,取肾脏和胃称重,观察肾脏病理变化。结果: 与CT组相比,造模结束后,所有模型组大鼠体重均显著降低(P＜0.01);除M2组外,其他造模组大鼠均有亡,M4组和M5组因死亡率高未做后续分析,M1和M3组分别死亡4例和2例;造模结束后,模型大鼠血尿酸、尿尿酸水平明显升高(P＜0.01),并且M2组的血尿酸水平显著高于其他各组(P＜0.05);继续喂养2周后,各模型组的血尿酸和尿尿酸水平仍显著升高(P＜0.05);各模型组大鼠肾脏重量也明显增加(P＜0.01);病理检查显示,模型组大鼠肾脏出现明显炎症反应和结构破坏。结论: 采用酵母膏(10 g/kg)、腺嘌呤(100 mg/kg)联合氧嗪酸钾(300 mg/kg)间隔(第1、3、7日)注射的方案可在短期内安全地诱导高尿酸血症大鼠模型,模型效果持续时间较长,适合在相关研究中应用。     

Augmented efficacy of tamoxifen in rat breast tumorigenesis when gavaged along with riboflavin, niacin, and CoQ10: effects on lipid peroxidation and antioxidants in mitochondria

Reactive oxygen species (ROS) play a major role in causing mitochondrial changes linked to cancer and metastasis. Uptake of antioxidants by tissue to reduce the ROS production could be instrumental in controlling cancer. Tamoxifen (TAM), a nonsteroidal anti-estrogen drug most used in the chemotherapy and chemoprevention of breast cancer. Riboflavin, niacin and coenzyme Q10 (CoQ10) are proved to be potent antioxidants and protective agents against many diseases including cancer. The objective of this research is to determine the therapeutic efficacy of combinatorial therapy on mammary carcinoma bearing rats in terms of the mitochondrial lipid peroxidation and antioxidant status especially MnSOD. Female albino rats of Sprague-Dawley strain were selected for the investigation. Mammary carcinoma was induced with 7,12-dimethyl benz(a)anthracene (DMBA: 25 mg), and the treatment was started by the oral administration of TAM (10 mg/kg body weight/day) along with riboflavin (45 mg/kg body weight/day), niacin (100 mg/kg body weight/day) and CoQ10 (40 mg/kg body weight/day) for 28 days. The levels of lipid peroxides, activities of enzymic and non-enzymic antioxidants were measured in the mitochondria isolated from the mammary gland and liver of control and experimental rats. Rats treated with DMBA showed an increase in mitochondrial lipid peroxidation (mammary gland 52.3%; liver 25.1%) accompanied by high malondialdehyde levels along with lowered activities of mitochondrial enzymic antioxidants [superoxide dismutase (mammary gland 19.9%; liver 24.8%), catalase (mammary gland 50%; liver 19.7%), glutathione peroxidase (mammary gland 47.8%; liver 31.1%)] and non-enzymic antioxidants [reduced glutathione (mammary gland 14.3%; liver 13.3%), Vitamin C (mammary gland 6.49%; liver 21.4%) and E (mammary gland 20.3%; liver 22.2%)]. Administration of combinatorial therapy restored lipid peroxide level and the activities of enzymic and non-enzymic antioxidants to near normalcy. In addition, antitumour activity was also found to be enhanced which is evident from the increased expression of tumour suppressor gene MnSOD thereby preventing cancer cell proliferation. These results suggested that TAM treatment is the most effective during co-administration of riboflavin, niacin and CoQ10 in terms of mitochondrial antioxidant and antitumour activity.     

Study of the factors influencing cardiac growth. III. Digitoxin treatment and thyroxine-induced cardiac hypertrophy in the rat

Thyroxine (T4) administered to rats in a dose of 1 mg/kg for 12 days induces cardiac hypertrophy. The purpose of the present study was to determine the effect of prophylactic + simultaneous digitoxin treatments on the development of T4-induced cardiac hypertrophy. Digitoxin (1 mg/kg body weight) was given per os, once daily for 6 days prior to T4 administration and continued simultaneously with T4 treatment. To determine myocardial enlargement, wet heart weight, myocardial nucleic acid and protein were measured. Digitoxin treatment induced a slight increase in wet ventricle weight and a significant elevation of myocardial RNA content (mg/ventricles) and concentration (mg/g). At the same time, the degree of T4-induced cardiac hypertrophy in digitoxin-treated and untreated animals was nearly the same. On the basis of these results it can be stated that--unlike the cardiac hypertrophy induced by pressure overload or hypoxia,--the T4-induced cardiac hypertrophy is not altered by digitoxin administration.     

Use of clarithromycin in the treatment of atopic dermatitis complicated by staphylococcal infection]

Thirty patients (19 boys and 11 girls) with atopic dermatitis complicated by pyodermia were treated with clarithromycin tablets (Fromilid, KRKA, Slovenia) in a dose of 7.5 mg/kg body weight twice a day. The average treatment course was 7 days. The severity of atopic dermatitis was evaluated by the SCARAD Index. Thirty patients of the reference group were treated with intramuscular lincomycin in a dose of 10-20 mg/kg body weight twice a day for 7 days. The difference in the average SCORAD Index before and after the treatment with clarithromycin amounted to 19.95 vs 14.68 (p < 0.005) with the use of lincomycin. The tolerance of clarithromycin was good.     

Cardiomegaly produced by chronic beta-adrenergic stimulation in the rat: comparison with alpha-adrenergic effects.

Chronic administration of d, l isoproterenol, 0.2 – 5 mg/kg/day, for 14–21 days in the male rat produced marked increases in dry ventricle weight (21.1 – 43.6%; p < 0.001). In comparison, an α-adrenergic agonist, phenylephrine (7.5 mg/kg/day) decreased ventricle weight (?15.3%; p < 0.025). Also, isoproterenol injection at 5 mg/kg/day decreased cardiac actomyosin ATPase activity by 23.3% (p < 0.0025) while phenylephrine, administered as above, did not influence ATPase activity. The effect of isoproterenol on heart weight was completely blocked by the β₁-adrenergic antagonist practolol (5 mg/kg/day). Albuterol, a relatively specific β₂-adrenergic agonist was less potent than isoproterenol in producing cardiac hypertrophy. l-Epinephrine injection, 0.8 mg/kg/day for 14 days, had no effect on heart weight. However, l-epinephrine produced cardiac hypertrophy (22.4% p < 0.001) when the animals were preinjected with the α-adrenergic antagonist, phenoxybenzamine (5 mg/kg/day). The data indicate that cardiac hypertrophy can be produced by stimulation of the β₁-adrenergic receptors of the heart; apparently, stimulation of α-adrenergic receptors opposes β-adrenergic hypertrophic effects.     

The mechanism of hypoglycemic action of the semi-purified fractions of Averrhoa bilimbi in streptozotocin-diabetic rats.

In the present study, we have examined the possible mechanism of the hypoglycemic action of the semi-purified fractions of an ethanolic extract of Averrhoa bilimbi Linn (Oxalidaceae) leaves (ABe) in streptozotocin-diabetic male Sprague-Dawley (SD) rats. The ABe was partitioned with water and butanol to yield a butanol-soluble fraction (BuF) and a water-soluble fraction (AF). The AF was further partitioned with ethyl acetate and hexane to obtain ethyl acetate (EF) and hexane (HF) soluble fractions. The hypoglycemic property of each fraction was assessed by the oral glucose tolerance test (OGTT) at a dose of 125-mg/kg-body weight in streptozotocin (STZ)-diabetic rats (STZ 60 mg/kg i.p.). Fractions AF, BuF and the reference drug metformin (500 mg/kg body weight), produced significant blood glucose-lowering effect in the diabetic rats when compared to the vehicle (distilled water). In the long-term study, the diabetic rats were randomly divided into 4 groups and treated orally by gavage with vehicle, AF (125 mg/kg body weight), BuF (125 mg/kg body weight), and metformin (500 mg/kg body weight) respectively twice a day for 14 days. On day 7 and day 14, AF and BuF, like the reference drug, metformin, lowered the fasting blood glucose concentration significantly (P < 0.05) when compared with the vehicle. The serum insulin level was significantly increased in the AF-treated rats only on day 14 when compared to that in the vehicle-treated rats on day zero (P < 0.05). The serum insulin level in BuF-treated rats was also significantly higher (P < 0.05) on both day 7 and day 14 compared to that on day zero. Hepatic glucose-6-phosphatase activity was significantly lower (P<0.05) in AF- and metformin-treated groups, but not in BuF-treated groups, compared to that in vehicle-treated group. However, there was no change in hepatic glycogen content in AF-, BuF- and metformin-treated group compared to the vehicle-treated group. These results indicate that AF is more potent than BuF in the amelioration of hyperglycemia in STZ-diabetic rats and is a potential source for the isolation of new orally active agent(s) for anti-diabetic therapy.     

Role of adrenergic mechanisms in the development of cardiac hypertrophy.

This experiment was designed to study the role of cardiac beta-adrenergic mechanisms in the development of hypertrophy in rats. The suprarenal abdominal aorta was banded, resulting in an increase in cardiac wt-body wt ratio. A group of rats received a sham operation. Half of the banded rats were treated with practolol, 2.0 mg/kg intraperitoneally every 12 hr for the 6 days after banding. The effectiveness of cardiac beta-adrenergic blockade was confirmed by absence of an increase in heart rate following intravenous isoproterenol at various times between practolol injections. Practolol did not affect the gradient in the banded groups. Six animals in each banded group were sacrificed daily for 6 days. The right and left ventricles were dissected separately and weighed. RV-body weight ratios increased similarly in both banded groups. LV-body weight ratio (g/kg) was 2.17 +/- 0.043 in sham rats, and it attained maximal levels of 3.03 +/- 0.10 within 6 days in banded untreated rats and 2.96 +/- 0.14 in banded rats receiving practolol. Therefore, beta-adrenergic mechanisms were not involved in the development of hypertrophy due to increased afterload. Also, these findings are not consistent with the Meerson hypothesis, since hypertrophy occurred despite the reduction in myocardial O2 consumption due to practolol.     

Acute liver damage induced by 2-nitropropane in rats: effect of diphenyl diselenide on antioxidant defenses

The effect of post-treatment with diphenyl diselenide on liver damage induced by 2-nitropropane (2-NP) was examined in male rats. Rats were pre-treated with a single dose of 2-NP (100 mg/kg body weight dissolved in canola oil). Afterward, the animals were post-treated with a dose of diphenyl diselenide (10, 50 or 100 micromol/kg). The parameters that indicate tissue damage such as liver histopathology, plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), urea and creatinine were determined. Since the liver damage induced by 2-NP is related to oxidative damage, lipid peroxidation, superoxide dismutase (SOD), catalase (CAT) and ascorbic acid level were also evaluated. Diphenyl diselenide (50 and 100 micromol/kg) effectively restored the increase of ALT and AST activities and urea level when compared to the 2-NP group. At the higher dose, diphenyl diselenide decreased GGT activity. Treatment with diphenyl diselenide, at all doses, effectively ameliorated the increase of hepatic and renal lipid peroxidation when compared to 2-NP group. 2-NP reduced CAT activity and neither alter SOD activity nor ascorbic acid level. This study points out the involvement of CAT activity in 2-NP-induced acute liver damage and suggests that the post-treatment with diphenyl diselenide was effective in restoring the hepatic damage induced by 2-NP.     

Increase in type I adenosine 3',5'-monophosphate-dependent protein kinase during isoproterenol-induced cardiac hypertrophy.

The amount of type I and type II cyclic AMP-dependent protein kinase present in the rat heart was determined at various times during isoproterenol-induced cardiac hypertrophy. Wistar rats were injected twice daily with isoproterenol (5 mg/kg, s.c.) for 2, 5 or 10 days. Cardiac weight increased gradually over the 10-day period of drug administration, and by day 10, heart weight was 156% of control. Following the cessation of isoproterenol administration, the cardiac weight regressed toward the control value by day 15. An increase in the specific activity of type I protein kinase to 197% of control occurred by day 10. The specific activity of type II protein kinase did not change significantly during either the hypertrophy or regression stage. The increase in the specific activity of type I protein kinase during a chemically-induced trophic response of the heart may indicate that type I cyclic AMP-dependent protein kinase plays a regulatory function in this process.     

内源性硫化氢在脂多糖引起的肺动脉高压中的作用

为观察硫化氢(hydrogen sulfide,H2s)在脂多糖(1ipopolysaccharide,LPS)引起的肺动脉高压中的作用,应用离体血管环张力测定方法测定肺动脉反应性,采用生物化学方法测定肺动脉组织中H2S产出率和胱硫醚-γ-裂解酶(cystathionine γ-lyase,CSE)活性,定量PCR方法测定肺动脉组织中CSE表达水平.结果如下:(1)与对照组相比,LPS可显著升高肺动脉平均压(mean pulmonary arterial pressure,mPAP)[(1.82±0.29)kPa vs(1.43±0.26)kPa,P<0.01],降低肺动脉组织中H2S产出率[(26.33±7.84)vs(42.92±8.73)pmoFg wet tissue per minute,P<0.01]和ACh诱导的肺动脉内皮依赖性舒张反应[(75.72±7.22)%vs(86.40±4.40)%,P<0.01];(2)NariS可部分逆转上述变化,而PPG加剧上述变化;(3)CSE活性和CSE mRNA表达的变化与H2S产出率的变化相同.结果提示,LPS对内皮依赖性舒张反应的抑制导致肺动脉高压的发生,此作用可能与H2S有关.     

Agiotensin II induced cardiac hypertrophy in vivo is inhibited by cyclosporin A in adult rats

Recently, the calciumcalmodulindependent calcineurin pathway has been defined as a central pathway for the induction of cardiac hypertrophy. The purpose of this study was to determine if cardiac hypertrophy in animals chronically treated with angiotensin II (AngII), could be prevented by blocking this pathway with cyclosporin A (CsA). Female Wistar rats were treated with AngII by subcutaneous infusion and injected twice a day with CsA (25 mg/kg) for 7 days. In the AngII treated group there was a 30% increase in the heart/body weight ratio (p < 0.05 vs. control). The increase in heart weight was blocked with CsA. Substantial increases in ANF and MHC gene expression were detected in the AngII treated animals, which were either attenuated or blocked with CsA treatment. Thus, this study demonstrates that CsA does prevent the development of cardiac hypertrophy in Ang II treated rats, suggesting that the calciumcalmodulindependent calcineurin pathway is associated with angiotensin II induced hypertrophy in vivo.     

The chemical chaperone 4-phenylbutyric acid attenuates pressure-overload cardiac hypertrophy by alleviating endoplasmic reticulum stress

Evidence has shown that endoplasmic reticulum stress (ERS) is associated with the pathogenesis of cardiac hypertrophy. The aim of this study was to investigate whether direct alleviation of ER stress by 4-phenylbutyric acid (PBA), a known chemical chaperone drug, could attenuate pressure-overload cardiac hypertrophy in mice. The effects of orally administered PBA (100mg/kg body weight daily for a week) were examined using mice undergoing transverse aortic constriction (TAC-mice), an animal model to produce pressure overload. TAC application for 1 week led to a 1.8-fold increase in the ratio of the heart weight over body weight (HW/BW) and up-regulation of the hypertrophy markers ANF and BNF accompanied by up-regulation of ERS markers (GRP78, p-PERK, and p-elF2α). The oral administration of PBA to the TAC-mice reduced hypertrophy (19%) and severely downregulated the fibrosis-related genes (transforming growth factor-β1, phospho-smad2, and pro-collagen isoforms). We conclude that ERS is induced as a consequence of remodeling during pathological hypertrophy and that PBA may help to relieve ERS and play a protective role against cardiac hypertrophy and possibly heart failure. We suggest PBA as a novel therapeutic agent for cardiac hypertrophy and fibrosis.