The phospholipase A(2) inhibitor methyl indoxam suppresses diet-induced obesity and glucose intolerance in mice.

BACKGROUND AND PURPOSE: Previous results have shown that mice lacking in the group 1B phospholipase A(2) (Pla2g1b) are resistant to obesity and diabetes induced by feeding a diabetogenic high-fat/high-carbohydrate diet. This study examined the potential of using the Pla2g1b inhibitor methyl indoxam as therapy to suppress diet-induced obesity and diabetes. EXPERIMENTAL APPROACH: Male C57BL/6 mice were fed the diabetogenic diet with or without methyl indoxam supplementation. Body weight gain, fasting plasma glucose levels, glucose tolerance and postprandial lysophospholipid absorption were compared. KEY RESULTS: Wild-type C57BL/6 mice fed the diabetogenic diet without Pla2g1b inhibitor showed 31 and 69% body weight gain after 4 and 10 weeks respectively. These animals also showed elevated plasma glucose levels and were glucose intolerant. In contrast, C57BL/6 mice fed the diabetogenic diet with 90 mg.kg(-1) of methyl indoxam gained only 5% body weight after 10 weeks. These animals were also euglycaemic and displayed normal glucose excursion rates in glucose tolerance test. Methyl indoxam suppression of diet-induced body weight gain and glucose intolerance was correlated with the inhibition of Pla2g1b-mediated postprandial lysophospholipid absorption. CONCLUSIONS AND IMPLICATIONS: These results show that oral supplementation of a diabetogenic diet with the Pla2g1b inhibitor methyl indoxam effectively suppresses diet-induced obesity and diabetes in mice. This suggests that Pla2g1b inhibition may be a potentially effective oral therapeutic option for treatment of obesity and diabetes.

Separation and quantitation of bile acids using an isocratic solvent system for high performance liquid chromatography coupled to an evaporative light scattering detector.

We developed a quantitative method for the analysis of bile acids using a high performance liquid chromatograph coupled to an evaporative light scattering detector. An isocratic solvent system was used to resolve in a single run conjugated and unconjugated bile acid species relevant in human and rodent physiology. The detection of various bile acids was linear over a range of 0.08 to 10 nmol of injected molecules. The developed system is a convenient and cost-effective method for the routine analysis of a wide variety of bile acids.

Expression of cholesterol 7alpha-hydroxylase restores bile acid synthesis in McArdle RH7777 cells.

Bile acid synthesis involves several enzymes and occurs only in liver cells. The first and rate-determining step is catalyzed by cholesterol 7alpha-hydroxylase (cyp7a). McArdle RH7777 hepatoma cells do not synthesize bile acids and do not express the cyp7a gene. A synthetic cyp7a gene was stably expressed in this cell line to determine if restoration of cyp7a activity is sufficient to reconstitute the bile acid synthetic pathway. The transfected cells contained the recombinant cyp7a mRNA and the corresponding protein. Microsomes from recombinant cells converted cholesterol into 7alpha-hydroxycholesterol, indicating that the recombinant enzyme was active. Radiolabeled bile acids, originated from exogenously supplied radiolabeled cholesterol, were detected in the culture medium of recombinant cells. Thus, expression of cyp7a is sufficient in restoring bile acid synthesis in McArdle RH7777 cells. The results also show that the additional complement of enzymatic activities required to convert cholesterol into bile acids has remained active in this cell line.