Effect of tetrapeptide on insulin biosynthesis in rats with alloxan-induced diabetes

Probiotics decreased the bioavailability of the bile acid analog, monoketocholic acid, when coadministered with gliclazide, in healthy but not diabetic rats

In recent studies we showed that gliclazide has no hypoglycemic effect on type 1 diabetic (T1D) rats while MKC does, and their combination exerted a better hypoglycemic effect than MKC alone. We also showed that the most hypoglycemic effect was noticed when T1D rats were treated with probiotics then gavaged with MKC + gliclazide (blood glucose decreased from 24 ± 3 to 10 ± 2 mmol/l). The aim of this study is to investigate the influence of probiotics on MKC pharmacokinetics when coadministered with gliclazide, in T1D rats. 80 male Wistar rats (weight 350 ± 50 g) were randomly allocated into 8 groups (10 rats/group), 4 of which were injected with alloxan (30 mg/kg) to induce T1D. Group 1 was healthy and group 2 was diabetic. Groups 3 (healthy) and 4 (diabetic) were gavaged with probiotics (75 mg/kg) every 12 h for 3 days and 12 h later all groups received a single oral dose of MKC + gliclazide (4 and 20 mg/kg respectively). The remaining 4 groups were treated in the same way but administered MKC + gliclazide via the i.v. route. Blood samples collected from T1D rats prior to MKC + gliclazide revealed that probiotic treatment alone reduced blood glucose levels twofold. When coadministered with gliclazide, the bioavailability of MKC was reduced in healthy rats treated with probiotics but remained the same in diabetic pretreated rats. The decrease in MKC bioavailability, when administered with gliclazide, caused by probiotic treatment in healthy but not diabetic rats suggests that probiotic treatment induced MKC metabolism or impaired its absorption, only in healthy animals. The different MKC bioavailability in healthy and diabetic rats could be explained by different induction of presystemic elimination of MKC in the gut by probiotic treatment.

Probiotic treatment reduces blood glucose levels and increases systemic absorption of gliclazide in diabetic rats

The action of gliclazide, a sulphonylurea with beneficial extrapancreatic effects in diabetes, may be enhanced by administering probiotics. The aim of this study was to investigate the influence of probiotics on gliclazide pharmacokinetics and the effect of both probiotics and gliclazide on blood glucose levels in healthy and diabetic rats. Male Wistar rats (2 to 3 months, weight 350 +/- 50 g) were randomly allocated to 4 groups (n =10), two of which were treated with alloxan i.v. 30 mg/kg to induce diabetes. One group of healthy and one group of diabetic rats were then gavaged with probiotics (75 mg/kg) for three days after which a gliclazide suspension (20 mg/kg) was administered by gavage to all groups. Blood samples were collected from the tail vein at various time points for 10 hours post-administration for the determination of blood glucose and gliclazide serum concentrations. It was found that probiotic treatment had no effect on blood glucose levels in healthy rats, but it reduced them (up to 2-fold; p < 0.01) in diabetic rats. Probiotic treatment reduced gliclazide bioavailability in healthy rats (3-fold) whereas it increased gliclazide bioavailability in diabetic rats (2-fold; p < 0.01). Gliclazide had no effect on blood glucose levels in either healthy or diabetic rats despite the changes in its bioavailability. In conclusion, the probiotic treatment of diabetic rats increases gliclazide bioavailability and lowers blood glucose levels by insulin-independent mechanisms, suggesting that the administration of probiotics may be beneficial as adjunct therapy in the treatment of diabetes.

Probiotic Pre-treatment Reduces Gliclazide Permeation (ex vivo) in Healthy Rats but Increases It in Diabetic Rats to the Level Seen in Untreated Healthy Rats

Aim

To investigate the influence of probiotic pre-treatment on the permeation of the antidiabetic drug gliclazide in healthy and diabetic rats.

Methods

Wistar rats (age 2–3 months, weight 350 ± 50 g) were randomly allocated into one of 4 groups (N = 16 each group): healthy control, healthy probiotic, diabetic control, and diabetic probiotic. Probiotics (75 mg/kg, equal quantities of Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus rhamnosus) were administered twice a day for three days to the appropriate groups after diabetes had been induced with alloxan i.v. 30 mg/kg. Rats were sacrificed, ileal tissues mounted in Ussing chambers and gliclazide (200 µg/mL) was administered for the measurement of the mucosal to serosal absorption Jss^(MtoS) and serosal to mucosal secretion Jss^(StoM) of gliclazide.

Results

Treatment of healthy rats with probiotics reduced Jss^(MtoS) of gliclazide from 1.2 ± 0.3 to 0.3 ± 0.1 µg/min/cm² (P < 0.01) and increased Jss^(StoM)from 0.6 ± 0.1 to 1.4 ± 0.3 (P < 0.01) resulting in net secretion while, in diabetic tissues, treatment with probiotics increased both Jss^(MtoS) and Jss^(StoM)fluxes of gliclazide to the comparable levels of healthy tissues resulting in net absorption.

Discussion

In healthy rats, the reduction in Jss^(MtoS) after probiotics administration could be explained by the production of bacterial metabolites that upregulate the mucosal efflux drug transporters Mrp2 that control gliclazide transport. In diabetic rats, the restored fluxes of gliclazide after probiotic treatment, suggests the normalization of the functionality of the drug transporters resulting in a net absorption.

Conclusion

Probiotics may alter gliclazide transport across rat ileal tissue studied ex vivo.