Taurine Improves the Actions of Metformin and Lovastatin on Plasma Markers of Carbohydrate and Lipid Dysfunction of Diabetic Rats.

Abstract

The present study has investigated the effect of adding taurine (TAU) to a treatment of diabetes with metformin (MET), a hypoglycemic, and lovastatin (LOV), an antihyperlipidemic. To this end, male Sprague-Dawley rats, agent, 250-275g in weight, were made diabetic with a single 60mg/kg intraperitoneal (i.p.) dose of streptozocin (STZ) in 10mM citrate buffer pH 4.5, and, after 14days, treated daily with oral doses of MET (2.4mM/kg), LOV (0.075mM/kg) or TAU (2.4mM/kg), and with binary and ternary combinations of these agents. Rats receiving only 10mM citrate buffer pH 4.5 or only STZ served as negative and positive controls, respectively. In addition, rats receiving insulin (INS, 4 units/kg) by the subcutaneous route served as a reference treatment. All the rats were sacrificed on day 57 and their bloods collected into heparinized tubes. The corresponding plasma samples were analyzed for their glucose (GLC), insulin (INS), glycated hemoglobin (HbA1c), cholesterol (CHOL) and triglycerides (TG) contents. In comparison to normal rats, diabetic ones showed marked increases in GLC (+313%), HbA1c (+207%), CHOL (+66%) and TG (+188) and a profound decrease of INS levels (-76%) (p<0.001 vs. control values). Among the various treatments, one with INS produced the greatest lowering effect on the plasm a GLC (+23%, p<0.05), INS (+23%, p<0.05) and TG (+3%), with the remaining changes being similar to those seen with MET. A treatment with MET reduced all the diabetic changes by at least threefold; and one with LOV had a significant (p<0.001) lowering effect on the plasma CHOL and TG but was without an effect on the plasma GLC, INS and HbA1c. In common with LOV, TAU reduced the diabetic levels of both CHOL and TG and, in addition, reduced the diabetic plasma GLC and raised the corresponding INS level. Among binary combinations, one with LOV-MET provided a greater effect than MET alone only in terms of the plasma CHOL and TG; and one with LOV-TAU was only significantly better than TAU alone in lowering the TG levels. However, a treatment with LOV-MET-TAU led to reductions in all the plasma parameters examined that were much greater than those achieved with any of the individual agents or with their binary combinations (at p≤0.05).