Pharmacokinetics of verapamil in diabetic rats induced by combination of high-fat diet and streptozotocin injection

et al. 2014

Acta Pharmacol Sin

Aim: Simvastatin is frequently administered to diabetic patients with hypercholesterolemia. The aim of the study was to investigate the pharmacokinetics of simvastatin and its hydrolysate simvastatin acid in a rat model of type 2 diabetes. Methods: Diabetes was induced in 4-week-old rats by a treatment of high-fat diet combined with streptozotocin. After the rats received a single dose of simvastatin (20 mg/kg, po, or 2 mg/kg, iv), the plasma concentrations of simvastatin and simvastatin acid were determined. Simvastatin metabolism and cytochrome P4503A (Cyp3a) activity were assessed in hepatic microsomes, and its uptake was studied in freshly isolated hepatocytes. The expression of Cyp3a1, organic anion transporting polypeptide 2 (Oatp2), multidrug resistance-associated protein 2 (Mrp2) and breast cancer resistance protein (Bcrp) in livers was measured using qRT-PCR. Results: After oral or intravenous administration, the plasma concentrations and areas under concentrations of simvastatin and simvastatin acid were markedly decreased in diabetic rats. Both simvastatin metabolism and Cyp3a activity were markedly increased in hepatocytes of diabetic rats, accompanied by increased expression of hepatic Cyp3a1 mRNA. Furthermore, the uptake of simvastatin by hepatocytes of diabetic rats was markedly increased, which was associated with increased expression of the influx transporter Oatp2, and decreased expression of the efflux transporters Mrp2 and Bcrp. Conclusion: Diabetes enhances the metabolism of simvastatin and simvastatin acid in rats via up-regulating hepatic Cyp3a activity and expression and increasing hepatic uptake.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decreased exposure of simvastatin and simvastatin acid in a rat model of type 2 diabetes

et al. 2014

Acta Pharmacol Sin

“…Experimental type 2 diabetic rats were induced by combination of high-fat diet and low-dose STZ injection according to a method described previously (Reed et al 2000, Chen et al 2011. Following an acclimation period of 3 days, the rats were assigned randomly to three groups: control (CON) group, high-fat diet-fed (HFD) group, and diabetic (DM) group.…”

Section: Induction Of Experimental Diabetes In Rats and Gts Treatmentmentioning

confidence: 99%

Increased glucagon-like peptide-1 secretion may be involved in antidiabetic effects of ginsenosides

Liu

Journal of Endocrinology

et al. 2013

Panax ginseng is one of the most popular herbal remedies. Ginsenosides, major bioactive constituents in P. ginseng, have shown good antidiabetic action, but the precise mechanism was not fully understood. Glucagon-like peptide-1 (GLP1) is considered to be an important incretin that can regulate glucose homeostasis in the gastrointestinal tract after meals. The aim of this study was to investigate whether ginseng total saponins (GTS) exerts its antidiabetic effects via modulating GLP1 release. Ginsenoside Rb1 (Rb1), the most abundant constituent in GTS, was selected to further explore the underlying mechanisms in cultured NCI-H716 cells. Diabetic rats were developed by a combination of high-fat diet and low-dose streptozotocin injection. The diabetic rats orally received GTS (150 or 300 mg/kg) daily for 4 weeks. It was found that GTS treatment significantly ameliorated hyperglycemia and dyslipidemia, accompanied by a significant increase in glucose-induced GLP1 secretion and upregulation of proglucagon gene expression. Data from NCI-H716 cells showed that both GTS and Rb1 promoted GLP1 secretion. It was observed that Rb1 increased the ratio of intracellular ATP to ADP concentration and intracellular Ca 2C concentration. The metabolic inhibitor azide (3 mM), the K ATP channel opener diazoxide (340 mM), and the Ca 2C channel blocker nifedipine (20 mM) significantly reversed Rb1-mediated GLP1 secretion. All these results drew a conclusion that ginsenosides stimulated GLP1 secretion both in vivo and in vitro. The antidiabetic effects of ginsenosides may be a result of enhanced GLP1 secretion. Key Words" glucagon-like peptide-1 (GLP1)" ginsenosides " Rb1" type 2 diabetes " ginseng total saponins (GTS)

“…Hepatic microsomes of rats were prepared according to the methods described previously [23,31] . Paroxetine metabolism in microsomes was investigated using the substrate depletion approach described by Obach [32] .…”

Section: Metabolism Of Paroxetine In Hepatic Microsomesmentioning

confidence: 99%

“…Diabetic (DM) rats were induced by the combination of a high-fat diet and low-dose STZ injection according to a previously described method [23,24] . Briefly, high-fat diet (HFD) rats and DM rats were both fed with a high-fat diet that consisted of 15% lard (w/w), 5% sesame oil, 20% sucrose, 2.5% cholesterol and 57.5% normal chow.…”

Section: Animals and Treatmentmentioning

confidence: 99%

Co-administration of paroxetine and pravastatin causes deregulation of glucose homeostasis in diabetic rats via enhanced paroxetine exposure

et al. 2014

Acta Pharmacol Sin

Aim: Clinical evidence shows that co-administration of pravastatin and paroxetine deregulates glucose homeostasis in diabetic patients. The aim of this study was to verify this phenomenon in diabetic rats and to elucidate the underlying mechanisms. Methods: Diabetes mellitus was induced in male SD rats by a high-fat diet combined with a low-dose streptozotocin injection. The rats were orally administered paroxetine (10 mg/kg) and pravastatin (10 mg/d) or both the drugs daily for 28 d. The pharmacokinetics of paroxetine and pravastatin were examined on d 1 and d 28. Biochemical parameters including serum insulin, glucose and lipids were monitored during the treatments. An insulin-secreting cell line (INS-1) was used for measuring insulin secretion. Results: In diabetic rats, co-administration of paroxetine and pravastatin markedly increased the concentrations of both the drugs compared with administration of each drug alone. Furthermore, co-administration severely impaired glucose homeostasis in diabetic rats, as demonstrated by significantly increased serum glucose level, decreased serum and pancreatic insulin levels, and decreased pancreatic Insulin-2 mRNA and tryptophan hydroxylase-1 (Tph-1) mRNA levels. Treatment of INS-1 cells with paroxetine (5 and 10 μmol/L) significantly inhibited insulin secretion, decreased the intracellular insulin, 5-HT, Insulin-2 mRNA and Tph-1 mRNA levels. Treatment of the cells with pravastatin (10 μmol/L) significantly stimulated insulin secretion, which was weakened by co-treatment with paroxetine. Conclusion: Paroxetine inhibits insulin secretion at least via decreasing intracellular 5-HT and insulin biosynthesis. The deregulation of glucose homeostasis by co-administration of paroxetine and pravastatin in diabetic rats can be attributed to enhanced paroxetine exposure.