Cardioprotective effect of oleanolic acid on isoproterenol-induced myocardial ischemia in rats

This study was designed to investigate the protective effect of oleanolic acid (OA) against isoproterenol-induced myocardial ischemia in rat myocardium. Wistar strain rats were pretreated with OA (20, 40, and 60 mg/kg, s.c) for 7 days and then intoxicated with isoproterenol (ISO, 85 mg/kg, sc for 2 consecutive days). Heart were excised from the experimental animals and assessed for the activities of marker enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)], the levels of lipid peroxide products [thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD)], myeloperoxidase (MPO), lipid profiles [total cholesterol (TC), free cholesterol, ester cholesterol, triglycerides (TG), free fatty acids (FFA) and phospholipids (PL)], and membrane-bound ATPase enzymes (total ATPase, Na(+)K(+) ATPase, Ca(2 +) ATPase, and Mg(2 +) ATPase). Troponin T and I were estimated in plasma. Leakage of cardiac markers, elevated lipid peroxidation with increased lipid profiles and decreased activities of membrane-bound ATPase enzymes were confirmed the severe myocardial damage occurring as a consequence of isoproterenol-induced ischemia, and they also showed the significant improvement effected by oleanolic acid pretreatment. These findings provided evidence that oleanolic acid was found to be protecting rat myocardium against ischemic insult and the protective effect could attribute to its anti-oxidative, anti-hyperlipedemic, and anti-arrhythmic properties as well as its membrane-stabilizing action.     

Protective effect of Cardiospermum halicacabum leaf extract on glycoprotein components on STZ–induced hyperglycemic rats

ObjectiveTo investigate the protective role of Cardiospermum halicacabum (C. halicacabum) leaf extract on glycoprotein metabolism in streptozotocin (STZ)-induced diabetic rats.MethodsDiabetes was induced in male albino Wistar rats by intraperitonial administration of STZ. The C. halicacabum leaf extract (CHE) was administered orally to normal and STZ–diabetic rats for 45 days. The effects of C. halicacabum leaf extract (CHE) on plasma and tissue glycoproteins (hexose, hexosamine, fucose and sialic acid) were determined.ResultsThe levels of plasma and tissues glycoproteins containing hexose, hexosamine and fucose were significantly increased in STZ–induced diabetic rats. In addition, the level of sialic acid significantly increased in plasma and liver while decreased in kidney of STZ–induced diabetic rats. After administration of CHE to diabetic rats, the metabolic alteration of glycoprotein reverted towards normal levels.ConclusionsThe present study indicates that the CHE possesses a protective effect on abnormal glycoprotein metabolism in addition to its antihyperglycemic activity.     

Antihyperglycaemic effect of Casearia esculenta root extracts in streptozotocin-induced diabetic rats

The present study was carried out to evaluate the antihyperglycaemic effect of Casearia esculenta root extract and to study the activities of liver hexokinase and gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase in liver and kidney of normal and streptozotocin-induced diabetic rats. Oral administration of aqueous extract of root (300 mg/kg body weight) for 45 days resulted in a significant reduction in blood glucose from 250.79 +/- 12.65 to 135.70 +/- 8.90 and in a decrease in the activities of glucose-6-phosphatase and fructose-1,6-bishosphatase and an increase in the activity of liver hexokinase. However, in the case of 200 mg/kg body weight of extract, less activity was observed. The study clearly shows that the root extract of C. esculenta possesses potent antihyperglycaemic activity but weaker than that of glibenclamide.     

Transepithelial paracellular leakiness induced by chronic phorbol ester exposure correlates with polyp-like foci and redistribution of protein kinase C-alpha

Although exposure of LLC-PK1 epithelial cell sheets to phorbol esters (TPA) causes a near immediate and total decrease of transepithelial electrical resistance (TER), continuation of exposure for 3 to 4 days results in a tachyphylactic response as TER begins to return to control levels. Recovery of TER is maximal by 5 to 6 days, but reaches only 70 to 80% of control level. A reciprocal change in the transepithelial flux of D-mannitol indicates that the TER decrease is indicative of an increase in tight junction permeability. Exposure of cell sheets to TPA for several days also results in the appearance of multilayered polyp- like foci (PLFs) across the otherwise one cell layer thick cell sheets. The pattern of penetration of the electron dense dye, ruthenium red, from the apical surface, across the tight junction and into the lateral intercellular space indicates that the tight junctions of the cell sheet become uniformly leaky after acute exposure to TPA. However, when exposure is continued for several days, only the junctions of cells in the PLFs manifest leakiness. The decrease in TER following acute TPA exposure correlates with the translocation of protein kinase C-alpha (PKC alpha) into a membrane-associated compartment. With exposure of several days, only a trace of PKC alpha is visible by Western immunoblot, and this is in the membrane-associated compartment. Immunofluorescent microscopy indicates that the trace of PKC alpha seen in the Western immunoblots is ascribable distinctly to cells of the PLFs. Monolayer areas between PLFs show no discernible immunofluorescent signal. The data therefore indicate that tight junction barrier function may be restored in certain areas by the down regulation of PKC alpha from the membrane-associated compartment. Failure to down regulate may result in the paracellular leakiness and abnormal cell architecture of the PLFs. Possible implications of this model for in vivo epithelial tumor promotion are discussed.