Metformin In Rats Research Articles

Combined Administration of Metformin and Amprolium to Rats Affects Metabolism of Free Amino Acids in the Brain, Altering Behavior, and Heart Rate.

The risk of developing diabetes and cardiometabolic disorders is associated with increased levels of alpha-aminoadipic acid and disturbances in the metabolism of branched-chain amino acids. The side effects of the widely used antidiabetic drug metformin include impaired degradation of branched-chain amino acids and inhibition of intracellular thiamin transport. These effects may be interconnected, as thiamine deficiency impairs the functioning of thiamine diphosphate (ThDP)-dependent dehydrogenases of 2-oxo acids involved in amino acids degradation, while diabetes is often associated with perturbed thiamine status. In this work, we investigate the action of metformin in rats with impaired thiamine availability. The reduction in the thiamine influx is induced by simultaneous administration of the thiamine transporters inhibitors metformin and amprolium. After 24 days of combined metformin/amprolium administration, no significant changes in the total brain levels of ThDP or activities of ThDP-dependent enzymes of central metabolism are observed, but the affinities of transketolase and 2-oxoglutarate dehydrogenase to ThDP increase. The treatment also significantly elevates the brain levels of free amino acids and ammonia, reduces the antioxidant defense, and alters the sympathetic/parasympathetic regulation, which is evident from changes in the ECG and behavioral parameters. Strong positive correlations between brain ThDP levels and contents of ammonia, glutathione disulfide, alpha-aminoadipate, glycine, citrulline, and ethanolamine are observed in the metformin/amprolium-treated rats, but not in the control animals. Analysis of the obtained data points to a switch in the metabolic impact of ThDP from the antioxidant and nitrogen-sparing in the control rats to the pro-oxidant and hyperammonemic in the metformin/amprolium-treated rats. As a result, metformin administration along with the amprolium-reduced thiamine supply significantly perturb the metabolism of amino acids in the rat brain, altering behavioral and ECG parameters.

Study of the neuroprotective properties of metformin in rats with type 2 diabetes mellitus and brain injury induced by intracerebral hemorrhage

The aim of this study was to study the effect of metformin (Met) on the formation of the conditional passive avoidance skills, markers of neurogenesis and oxidative stress in the brain of rats with acute intracerebral hemorrhage (ICH) in the setting of streptozotocin-nicotinamide-induced diabetes. Type 2 diabetes mellitus (T2DM) was induced in rats via the intraperitoneal injection of streptozotocin (STZ) and nicotinamide (NA), ICH – by microinjection of bacterial collagenase into the striatum. Rats were randomly divided into four groups: 1 – intact animals (n=8), 2 – T2DM (n=9); 3 – T2DM+ICH (n=7); 4 – T2DM+ICH+Met (n=7). The passive avoidance test was used to evaluate behavioural activity. Advanced oxidation protein products (AOPP) and lactate were measured by spectrophotometry, advanced glycation end products (AGEs) by quantitative fluorescence, level of 8-hydroxy-2-deoxyguanosine (8-OHdG) was assessed by enzyme-linked immunosorbent assay (ELISA). Histopathological examination was performed using general histological staining techniques and immunohistochemical methods for assessment of expression of endothelial NO-synthase (eNOS), Growth Associated Protein 43 (GAP43), Hypoxia-inducible factor 1-alpha (HIF-1α), neural cadherine (N-cadherine) and vascular endothelial cadherine (VE-cadherine). In this study, metformin had nootropic (anti-amnestic) activity and decreased oxidative stress markers (AGEs, AOPPs and 8-OHdG) levels by 29.1% (p<0.001), 24.9% (p<0.015) and 29.3% (p<0.05) respectively, which indicates its positive impact on the course of free radical oxidation reactions intensified by both diabetes and intracerebral hemorrhage. The study provides additional information on neuroprotective properties of metformin and the emphasizes possibility of using metformin in diabetic patients at risk of hemorrhagic stroke. Considering the increase in VE-cadherin expression by the drug, it is possible to predict its positive effect on the function of blood-brain barrier. This study may serve as a reference for the feasibility of studying the clinical efficacy of metformin under these conditions.

Does sildenafil citrate affect the pharmacokinetics of metformin in rats? Screening of mechanism through analytical and molecular docking approach.

In the present study, the effect of sildenafil on the pharmacokinetics of metformin was studied in experimental rats, and we also postulated the molecular mechanism by performing molecular docking studies. Analysis of metformin and sildenafil (SIL) from rat plasma was done by high performance liquid chromatography. Optimum chromatographic separation and quantification of MET, SIL and Cetirizine was achieved on Phenomenex EVO C18 column with triethyl amine (0.3%): Methanol: Acetonitrile (70:05:25 v/v) as mobile phase maintaining flow rate of 1 ml/min, the detector was tuned at 224 nm. The extraction of MET and sildenafil from rat plasma was achieved by solid-phase extraction using Strata-X cartridges. The method was validated as per the ICH guidelines. For docking studies, the crystal structure of organic cation transporter 1 (OCT1) protein and multidrug and toxin extrusion (MATE) protein (5XJJ) were downloaded from the PubChem database. The docking study was performed by PyRx virtual screening software, and the results were analyzed by BIOVIA Discovery Studio. The validation of HPLC method was done, intraday and interday precision study of HPLC method demonstrated %RSD values less than 5%, the extraction recovery for MET and SIL were near to 80 % for low, medium and high QC samples. The plasma stability of MET and SIL showed % RSD values <10% for low, medium, and high QC samples. A sensitivity study for MET and SIL in rat plasma suggested a lower limit of quantification values of 8 and 10 ng/mL, respectively. The pharmacokinetic parameters were recorded, Cmax of experimental and control rats was 611.2 and 913.2 ng/mL; t1/2 1.66 and 1.98, AUC (0-t) 1637.5 and 2727.24, AUC (0-∞) 1832.38 and 2995.24 for MET. The results suggested that the Cmax of MET in experimental rats (MET + SIL) was 33.07% lower than the control (MET only) and also the t1/2 was 0.32 h shorter. Docking analysis suggested a higher binding affinity of sildenafil with MATE protein (5XJJ) compared to OCT1, suggesting possible involvement of MATE family proteins for pharmacokinetic alterations of MET. The HPLC and solid-phase extraction method were developed and applied successfully for the pharmacokinetics of MET and SIL. Intake of SIL altered the pharmacokinetics of MET in rats. Molecular docking studies suggested the involvement of MATE family proteins for alterations of MET pharmacokinetics.

Metformin Prevents Cocaine Sensitization: Involvement of Adenosine Monophosphate-Activated Protein Kinase Trafficking between Subcellular Compartments in the Corticostriatal Reward Circuit

Repeated cocaine exposure produces an enhanced locomotor response (sensitization) paralleled by biological adaptations in the brain. Previous studies demonstrated region-specific responsivity of adenosine monophosphate-activated protein kinase (AMPK) to repeated cocaine exposure. AMPK maintains cellular energy homeostasis at the organismal and cellular levels. Here, our objective was to quantify changes in phosphorylated (active) and total AMPK in the cytosol and synaptosome of the medial prefrontal cortex, nucleus accumbens, and dorsal striatum following acute or sensitizing cocaine injections. Brain region and cellular compartment selective changes in AMPK and pAMPK were found with some differences associated with acute withdrawal versus ongoing cocaine treatment. Our additional goal was to determine the behavioral and molecular effects of pretreatment with the indirect AMPK activator metformin. Metformin potentiated the locomotor activating effects of acute cocaine but blocked the development of sensitization. Sex differences largely obscured any protein-level treatment group effects, although pAMPK in the NAc shell cytosol was surprisingly reduced by metformin in rats receiving repeated cocaine. The rationale for these studies was to inform our understanding of AMPK activation dynamics in subcellular compartments and provide additional support for repurposing metformin for treating cocaine use disorder.

The Role of Glycogen Synthase Kinase-3β in the Zinc-Mediated Neuroprotective Effect of Metformin in Rats with Glutamate Neurotoxicity.

Metformin has been suggested to have protective effects on the central nervous system, but the mechanism is unknown. The similarity between the effects of metformin and the inhibition of glycogen synthase kinase (GSK)-3β suggests that metformin may inhibit GSK-3β. In addition, zinc is an important element that inhibits GSK-3β by phosphorylation. In this study, we investigated whether the effects of metformin on neuroprotection and neuronal survival were mediated by zinc-dependent inhibition of GSK-3β in rats with glutamate-induced neurotoxicity. Forty adult male rats were divided into 5 groups: control, glutamate, metformin + glutamate, zinc deficiency + glutamate, and zinc deficiency + metformin + glutamate. Zinc deficiency was induced with a zinc-poor pellet. Metformin was orally administered for 35days. D-glutamic acid was intraperitoneally administered on the 35th day. On the 38th day, neurodegeneration was examined histopathologically, and the effects on neuronal protection and survival were evaluated via intracellular S-100β immunohistochemical staining. The findings were examined in relation to nonphosphorylated (active) GSK-3β levels and oxidative stress parameters in brain tissue and blood. Neurodegeneration was increased (p < 0.05) in rats fed a zinc-deficient diet. Active GSK-3β levels were increased in groups with neurodegeneration (p < 0.01). Decreased neurodegeneration, increased neuronal survival (p < 0.01), decreased active GSK-3β (p < 0.01) levels and oxidative stress parameters, and increased antioxidant parameters were observed in groups treated with metformin (p < 0.01). Metformin had fewer protective effects on rats fed a zinc-deficient diet. Metformin may exert neuroprotective effects and increase S-100β-mediated neuronal survival by zinc-dependent inhibition of GSK-3β during glutamate neurotoxicity.

The Effect of Graviola Leaves Extract (Annona muricata L.) on Pharmacokinetic of Metformin in Rats’ Plasma and Pharmacological Activity of their Combination on Breast and Prostate Cancer Cell Lines

Objectives: Metformin is the most widely given medication for type 2 diabetes mellitus (T2DM). Annona muricata L. is a medicinal plant that belongs to the family Annonaceae, popularly known as graviola. Graviola leaves extract was found useful against diabetes, headache, insomnia, cystitis, inflammation, cancer, and other health benefits. The objectives of the current study are to investigate the effect of graviola leaves extract on metformin pharmacokinetics in rat plasma by applying high performance liquid chromatography (HPLC) method as well as its pharmacological effects on breast cancer (MCF-7) cells and prostate cancer (DU-145) cells. Methods: Wistar rats were classified into two groups; the first group (control group) received metformin (20 mg/kg) alone by oral gavage, while the second group, was administered a combination of metformin (20 mg/kg) and graviola leaves extract (20 mg/kg). Blood samples were collected at different time intervals to be analyzed using a validated HPLC method. Plasma profile and pharmacokinetic parameters were determined for each group. In addition, blood glucose levels at 0 hours and after 2 hours of metformin administration were measured in both groups. Breast cancer (MCF-7) cells and prostate cancer (DU-145) cells were used to investigate the anticancer effect of metformin (40 mg/ml), graviola leaves extract (20 mg/ml) and their combination by the standard MTT assay. Results: In the first group, metformin maximum plasma concentration (Cmax) and the area under the curve (AUC0-last) were (1509.25 ng/ml and 8705.59 h*ng/ml) respectively. In the second group, Pre-administration of graviola leaves extract significantly reduced MET (Cmax) and (AUC0-last), (701.88 ng/ml and 3467.72 h*ng/ml), respectively (P ≤0.05). Further, the use of metformin and graviola leaves extract separately showed strong anticancer activity on (MCF-7) cell lines with IC50 values of (10 and 20 mg/ml), respectively as well as on (DU-145) cell lines with IC50 value of (0.3125 and 5 mg/ml), respectively. In addition, the combination of metformin and graviola leaves extract showed a synergistic effect on (MCF-7) cells since the fractional inhibitory concentration value (FIC = 0.375) was less than 0.5, while it showed an additive effect on (DU-145) cells since the fractional inhibitory concentration value (FIC = 1.5) was between (0.5 and 4). Conclusion: In the current study, pre-administration of graviola leaves extract significantly reduced efficacy of metformin In vivo. The combination of metformin and graviola leaves extract showed a synergistic anticancer effect on breast cancer in vitro, while the combination has an additive effect on prostate cancer. The combination could be a potential therapeutic option to help treat breast cancer. The result achieved in this study is very encouraging to be considered for further investigation.

Restoration of aquaporin-4 polarization in the spinal glymphatic system by metformin in rats with painful diabetic neuropathy.

Painful diabetic neuropathy (PDN) is a common complication in patients with diabetes, and its underlying mechanism remains unclear. Aquaporin-4 (AQP4) plays a crucial role in removing metabolic waste in the glymphatic system. In this study, we aimed to explore the relationship between the spinal glymphatic system and the effect of metformin on PDN. Male Sprague-Dawley rats were randomly allocated into the control group ( n = 10), the PDN group ( n = 10), and the metformin group ( n = 10). A high-fat and high-glucose diet combined with low-dose streptozotocin was used to induce PDN rats. We detected the clearance rate of the contrast agent in the spinal cord of each rat by MRI to reflect the function of the glymphatic system. Immunofluorescence was used to detect the localization of perivascular AQP4 in astrocyte endfeet. Furthermore, we measured the expression of AQP4 in the spinal cord by Western blot. Compared with the rats in the control group, PDN rats exhibited enhanced mechanical allodynia, decreased clearance rate of the contrast agent in the spinal glymphatic system, reversed AQP4 polarization, and increased expression of AQP4. After being treated with metformin, the rats showed opposite changes in the above characteristics. The analgesic effect of metformin on PDN may be related to its ability to restore spinal AQP4 polarization, thus promoting the function of the spinal glymphatic system.

Evaluation of Protective Effect of Metformin in Rats with Experimental Osteoarthritis

Objective: The objective of this study is to evaluate metformin proposed protective effect against the development of osteoarthritis (OA) in rats. Materials and Methods: A total of 40 male Sprague–Dawley rats were included, divided into four groups: negative control (n = 10), positive control (OA induced by monoiodoacetate [MIA]) (n = 10), metformin 200mg/kg group (n = 10) preinduction of OA, and metformin 200 mg/kg group (n = 10) postinduction of OA. Serum C-telopeptide type II collagen (CTX-II), inflammatory biomarkers were evaluated for each group. For data analysis, SPSS version 26.00 was used. Results: Metformin-treated groups showed a significant reduction in inflammatory biomarkers and CTX-II serum levels compared with OA group (P &lt; 0.05). Pretreatment with 200 mg/kg metformin imparted extra cartilage protective effect and further decreased inflammatory cytokines compared to posttreated (P &lt; 0.05). Conclusion: Metformin produced a beneficial protective effect in experimental OA in rats. It attenuates the inflammatory reactions progression by preventing the release of pro-inflammatory cytokines in rats with experimental OA. Furthermore, metformin reduced cartilage degradation evidenced by lowering CTX-II serum levels experimental OA in rats.

Enalapril increases the urinary excretion of metformin in rats by inducing multidrug and toxin excretion protein 1 in the kidney.

Two-thirds of patients with type 2 diabetes mellitus (T2DM) have hypertension, and thus the combination of two or more drugs to treat these diseases is common. It has been shown that the combination of metformin and enalapril has beneficial effects, but few studies have evaluated the interactions between these two drugs. In this study we investigated the effects of enalapril on the pharmacokinetics and urinary excretion of metformin in rats, with a focus on transporter-mediated drug interactions. Rats were orally dosed with metformin alone (100 mg/kg) or in combination with enalapril (4 mg/kg). The concentration of metformin was measured by HPLC and the level of organic cation transporters (rOCTs) and multidrug and toxin excretion protein 1 (rMATE1), which mediate the uptake and efflux of metformin, respectively, were evaluated by immunoblotting. After single and 7-day dosing, the plasma concentration of metformin in the co-administration group was significantly lower than that in the metformin-only group, and the CL/F and urinary excretion were increased in the co-administration group. Enalapril did not affect the Kp of metformin but elevated slice-uptake of metformin. The expression of rMATE1 was increased, whereas rOCT2 expression was decreased in rat kidney. Importantly, long-term co-administration of metformin and enalapril markedly decreased the level of lactic acid and uric acid in the blood. Enalapril increases the urinary excretion of metformin through the up-regulation of rMATE1. This reveals a new mechanism of drug interactions and provides a basis for drug dosage adjustment when these drugs are co-administered. This article is protected by copyright. All rights reserved.

Antidiabetic Effect of Hexane Extract of Costus Speciosus and Metformin in Rats

Antidiabetic Effect of Hexane Extract of Costus Speciosus and Metformin in Rats

Gut microbiota modulation as a promising therapy with metformin in rats with non-alcoholic steatohepatitis: Role of LPS/TLR4 and autophagy pathways

Gut microbiota is a crucial factor in pathogenesis of non-alcoholic steatohepatitis (NASH). Therefore, targeting the gut-liver axis might be a novel therapeutic approach to treat NASH. This study aimed to investigate the therapeutic effects of a probiotic (Lactobacillus reuteri) and metronidazole (MTZ) (an antibiotic against Bacteroidetes) either alone or in combination with metformin (MTF) in experimentally-induced NASH. NASH was induced by feeding rats high fat diet (HFD) for 12 weeks. MTF (150mg/kg/day) or L. reuteri (2x109 colony forming unit/day) were given orally for 8 weeks; meanwhile, MTZ (15mg/kg/day, p.o.) was administered for 1 week. Treatment with L. reuteri and MTZ in combination with MTF showed additional benefit compared to MTF alone concerning lipid profile, liver function, oxidative stress, inflammatory and autophagic markers. Furthermore, combined regimen succeeded to modulate acetate: propionate: butyrate ratios as well as Firmicutes and Bacteroidetes fecal contents with improvement of insulin resistance (IR). Yet, the administration of MTF alone failed to normalize Bacteriodetes and acetate contents which could be the reason for its moderate effect. In conclusion, gut microbiota modulation may be an attractive therapeutic avenue against NASH. More attention should be paid to deciphering the crosstalk mechanisms linking gut microbiota to non-alcoholic fatty liver disease (NAFLD) to identify new therapeutic targets for this disease.

Pharmacokinetic Interaction between Sorafenib and Atorvastatin, and Sorafenib and Metformin in Rats.

The tyrosine kinase inhibitor sorafenib is the first-line treatment for patients with hepatocellular carcinoma (HCC), in which hyperlipidemia and type 2 diabetes mellitus (T2DM) may often coexist. Protein transporters like organic cation (OCT) and multidrug and toxin extrusion (MATE) are involved in the response to sorafenib, as well as in that to the anti-diabetic drug metformin or atorvastatin, used in hyperlipidemia. Changes in the activity of these transporters may lead to pharmacokinetic interactions, which are of clinical significance. The study aimed to assess the sorafenib−metformin and sorafenib−atorvastatin interactions in rats. The rats were divided into five groups (eight animals in each) that received sorafenib and atorvastatin (ISOR+AT), sorafenib and metformin (IISOR+MET), sorafenib (IIISOR), atorvastatin (IVAT), and metformin (VMET). Atorvastatin significantly increased the maximum plasma concentration (Cmax) and the area under the plasma concentration–time curve (AUC) of sorafenib by 134.4% (p < 0.0001) and 66.6% (p < 0.0001), respectively. Sorafenib, in turn, caused a significant increase in the AUC of atorvastatin by 94.0% (p = 0.0038) and its metabolites 2−hydroxy atorvastatin (p = 0.0239) and 4−hydroxy atorvastatin (p = 0.0002) by 55.3% and 209.4%, respectively. Metformin significantly decreased the AUC of sorafenib (p = 0.0065). The AUC ratio (IISOR+MET group/IIISOR group) for sorafenib was equal to 0.6. Sorafenib did not statistically significantly influence the exposure to metformin. The pharmacokinetic interactions observed in this study may be of clinical relevance in HCC patients with coexistent hyperlipidemia or T2DM.

Pharmacokinetic Interaction of Green Rooibos Extract With Atorvastatin and Metformin in Rats.

An aspalathin-rich green rooibos extract (Afriplex GRT™) has demonstrated anti-diabetic and hypolipidemic properties, while also moderately inhibiting CYP3A4 activity, suggesting a potential for herb–drug interaction. The present study, therefore, evaluated the effects of orally administered GRT on the pharmacokinetics of atorvastatin and metformin in Wistar rats. Wistar rats were orally treated with GRT (50 mg/kg BW), atorvastatin (40 mg/kg BW) or metformin (150 mg/kg BW) alone or 50 mg/kg BW GRT in combination with 40 mg/kg BW atorvastatin or 150 mg/kg BW metformin. Blood samples were collected at 0, 10, and 30 min and 1, 2, 4, 6, and 8 h and plasma samples obtained for Liquid chromatography-mass spectrometry (LC-MS/MS) analyses. Non-compartment and two-compartment pharmacokinetic parameters of atorvastatin and metformin in the presence or absence of GRT were determined by PKSolver version 2.0 software. Membrane transporter proteins, ATP-binding cassette sub-family C member 2 (Abcc2), solute carrier organic anion transporter family, member 1b2 (Slco1b2), ATP-binding cassette, sub-family B (MDR/TAP), member 1A (Abcb1a), and organic cation transporter 1 (Oct1) mRNA expression were determined using real-time PCR expression data normalized to β-actin and hypoxanthine-guanine phosphoribosyltransferase (HPRT), respectively. Co-administration of GRT with atorvastatin substantially increased the maximum plasma concentration (Cmax) and area of the plasma concentration–time curve (AUC0-8) of atorvastatin by 5.8-fold (p = 0.03) and 5.9-fold (p = 0.02), respectively. GRT had no effect on the plasma levels of metformin. GRT increased Abcc2 expression and metformin downregulated Abcb1a expression while the combination of GRT with atorvastatin or metformin did not significantly alter the expression of Slco1b1 or Oct1 did not significantly alter the expression of Sclo1b2 or Oct1. Co-administration of GRT with atorvastatin in rats may lead to higher plasma concentrations and, therefore, to an increase of the exposure to atorvastatin.

Enhanced Intestinal Permeability and Plasma Concentration of Metformin in Rats by the Repeated Administration of Red Ginseng Extract.

We aimed to assess the potential herb–drug interactions between Korean red ginseng extract (RGE) and metformin in rats in terms of the modulation of metformin transporters, such as organic cation transporter (Oct), multiple toxin and extrusion protein (Mate), and plasma membrane monoamine transporter (Pmat). Single treatment of RGE did not inhibit the in vitro transport activity of OCT1/2 up to 500 µg/mL and inhibited MATE1/2-K with high IC50 value (more than 147.8 µg/mL), suggesting that concomitant used of RGE did not directly inhibit OCT- and MATE-mediated metformin uptake. However, 1-week repeated administration of RGE (1.5 g/kg/day) (1WRA) to rats showed different alterations in mRNA levels of Oct1 depending on the tissue type. RGE increased intestinal Oct1 but decreased hepatic Oct1. However, neither renal Oct1/Oct2 nor Mate1/Pmat expression in duodenum, jejunum, ileum, liver, and kidney were changed in 1WRA rats. RGE repeated dose also increased the intestinal permeability of metformin; however, the permeability of 3-O-methyl-d-glucose and Lucifer yellow was not changed in 1WRA rats, suggesting that the increased permeability of metformin by multiple doses of RGE is substrate-specific. On pharmacokinetic analysis, plasma metformin concentrations following intravenous injection were not changed in 1WRA, consistent with no significant change in renal Oct1, Oct2, and mate1. Repeated doses of RGE for 1 week significantly increased the plasma concentration of metformin, with increased half-life and urinary excretion of metformin following oral administration of metformin (50 mg/kg), which could be attributed to the increased absorption of metformin. In conclusion, repeated administration of RGE showed in vivo pharmacokinetic herb–drug interaction with metformin, with regard to its plasma exposure and increased absorption in rats. These results were consistent with increased intestinal Oct1 and its functional consequence, therefore, the combined therapeutic efficacy needs further evaluation before the combination and repeated administration of RGE and metformin, an Oct1 substrate drug.

Lonicera japonica extract increases metformin distribution in the liver without change of systemic exposed metformin in rats

Ethnopharmacological relevanceFlower and flower bud of Lonicera japonica, Lonicerae Flos, have been popularly used as medicinal plant for the treatment of clearing heat and thirst, thereby improving diabetic or diabetic associated symptoms (thirst and poor eyesight). Aim of the studyOrganic cation transporters (OCTs) and multi-drug and toxin extrusion proteins (MATEs) are known to play important roles in metformin transport in the liver and kidneys. Thus, there might be interactions between Lonicerae Flos and metformin via OCTs and MATEs. Also treatment period has been issued in transporter-mediated drug interactions. The objective of this study was to determine the effect of Lonicerae Flos ethanol extract (LJ) on metformin pharmacokinetics and its glucose lowering activity in different treatment periods. Materials and methodsEffect of LJ on metformin uptake was evaluated in vitro HEK-293 cells expressing human OCTs or MATEs. Treatment period-dependent impact of LJ on systemic exposure and hepatic distribution of metformin as well as its glucose tolerance activity were assessed in in vivo rats. ResultsLJ substantially inhibited MATE1-mediated metformin uptake in vitro. In evaluating treatment period effects of LJ and metformin, 1-, 7-, and 28-day co-treatments of LJ with metformin did not change systemic exposure of metformin compared to those in metformin alone. Whereas, 28-day co-treatment of LJ with metformin increased metformin concentration in liver as a pharmacological target site of metformin. It could be due to the reduced MATE1-mediated metformin efflux from hepatocytes to bile by MATE1 inhibition in liver. Glucose tolerance activity was also enhanced by 28-day co-treatment of LJ and metformin compared to metformin alone. ConclusionsIn 28-day co-treatment of LJ and metformin, LJ increased metformin concentration in liver and improved glucose tolerance activity without systemic exposure change of metformin, suggesting the importance to consider treatment period effect and both systemic exposure and tissue distribution in drug interactions.

Preclinical Study to Evaluate the Effect of Polyherbal Formulation on Metformin: Potential Herb-drug Interaction

Objective: The aim of the present study was to examine the effect of a polyherbal formulation (PHF) on pharmacokinetics and pharmacodynamics of metformin in rats. Methods: The present study was conducted to determine the beneficial outcomes of PHF along with metformin by studying herb-drug interactions. PHF was prepared by five indigenous herbs, Those are being used traditionally as antidiabetic in India. PHF doses (100 mg/kg/day) were administered to Sprague-Dawley rats by an oral route of different groups for multiple weeks except for control. Metformin (100 mg/kg) was orally administered at 7th and 30th day to control and PHF pretreated rats for pharmacokinetics study while pharmacodynamics study was conducted in PHF treated and untreated diabetic rats. No more significant difference was found in the pharmacokinetic parameters in PHF treated at 7th day while a significant increase was found in AUC at the 30th day. Results: The hypoglycemic effect was observed with a combination of metformin and PHF, significantly more compared to control. Metformin decreased the blood glucose 1.51 fold at 7th day and 1.7 fold at 30th day respectively, compared to control. Conclusion: Thus, this finding indicates that PHF increased the AUC of metformin. It might increase bioavailability through drug-herb interaction thereby affecting the therapeutic effect. This formulation can be considered as an adjunct to metformin in the management of diabetes mellitus.

Boswellic Acids Pretreatment Enhances the Bioavailability and Hypoglycemic Action of Metformin in Rats: Involvement of CYP3A Inhibition

Boswellic Acids Pretreatment Enhances the Bioavailability and Hypoglycemic Action of Metformin in Rats: Involvement of CYP3A Inhibition

Organic cation transporter and multidrug and toxin extrusion 1 co-mediated interaction between metformin and berberine

Metformin and berberine are often combined for treating diabetes. In the present study, we evaluated the drug-drug pharmacokinetic interaction between metformin and berberine after oral co-administration in vivo and the underlying mechanism. As revealed by comparison with the metformin-only group, berberine significantly decreased the maximum plasma concentration (Cmax), area under the curve from 0 to 4 h (AUC0–4h), and urinary and bile excretion, and increased the kidney tissue concentration of metformin in rats. The non-everted intestinal sac study showed that berberine inhibited the absorption of metformin, and in transfected Madin-Darby canine kidney (MDCK)-rat organic cation transporter 1 (MDCK-rOCT1), MDCK-rat organic cation transporter 2 (MDCK-rOCT2), and MDCK-rat multidrug and toxin extrusion 1 (MDCK-rMATE1) cells, berberine significantly inhibited metformin transport mediated by OCT1, OCT2, and MATE1 in a concentration-dependent manner with half-maximal inhibitory concentration (IC50) values of 18.8, 1.02, and 10.7 μM, respectively. In contrast, co-administration of metformin increased the Cmax and AUC0-4h of berberine with no significant difference in pharmacokinetics parameters between co-administration and berberine-only groups. Furthermore, metformin increased kidney and liver concentrations and reduced the urinary and biliary excretion of berberine. Metformin (≥1 or ≥0.3 mM) decreased berberine transport in MDCK-rOCT1, MDCK-rOCT2, and MDCK-rMATE1 cells. However, metformin did not affect berberine concentration in MDCK-multidrug resistance protein 1 cells. These results suggest that the combination of metformin and berberine induced a pharmacokinetic interaction by cooperatively inhibiting OCT and MATE1-mediated transport.

A Study on Neonatal Intake of Oleanolic Acid and Metformin in Rats (Rattus norvegicus) with Metabolic Dysfunction: Implications on Lipid Metabolism and Glucose Transport.

Metabolic syndrome, a cluster of different disorders which include diabetes, obesity and cardiovascular diseases, is a global epidemic that is growing at an alarming rate. The origins of disease can be traced back to early developmental stages of life. This has increased mortalities and continues to reduce life expectancies of individuals across the globe. The aim of this study was to investigate the sub-acute and long term effects of neonatal oral administration of oleanolic acid and metformin on lipids (free fatty acids, FFAs) and genes associated with lipid metabolism and glucose transport using a neonatal rat experimental model. In the first study, seven days old pups were randomly grouped into control—distilled water (DW); oleanolic acid (60 mg/kg), metformin (500 mg/kg), high fructose diet (20% w/v, HF), oleanolic acid (OA) + high fructose diet (OA + HF), and Metformin + high fructose diet (MET + HF) groups. The pups were treated for 7 days, and then terminated on postnatal day (PD) 14. In the second study, rat pups were initially treated similarly to study 1 and weaned onto normal rat chow and plain drinking water on PD 21 till they reached adulthood (PD112). Tissue and blood samples were collected for further analyses. Measurement of the levels of free fatty acids (FFAs) was done using gas chromatography-mass spectrometry. Quantitative polymerase chain reaction (qPCR) was used to analyze the gene expression of glut-4, glut-5, fas, acc-1, nrf-1 and cpt-1 in the skeletal muscle. The results showed that HF accelerated accumulation of saturated FFAs within skeletal muscles. The HF fed neonatal rats had increased stearic acid, which was associated with decreased glucose, suppressed expression of glut-4, glut-5, nrf-1 and cpt-1 genes, and increased expression of acc-1 (p < 0.01) and fas. OA + HF and MET + HF treated groups had increased mono- and polyunsaturated FFAs; oleic, and octadecadienoic acids than the HF group. These unsaturated FFAs were associated with increased glut-4, glut-5 and nrf-1 (p < 0.01) and decreased acc-1 and fas (p < 0.05) in both OA + HF and MET + HF treated groups. Conclusions: The present study shows that neonatal oral administration of oleanolic acid and metformin potentially protects against the development of fructose-induced metabolic dysfunction in the rats in both short and long time periods.

Abstract 1250: Evaluation of the prevention by pioglitazone/metformin of ER-positive and ER-negative mammary cancers occurring in rodents on a high-fat diet

Abstract Both metformin and pioglitazone have demonstrated cancer chemopreventive properties. Actoplus/Met, a combination of the two agents, is currently used in the clinic with an additive effect on improving insulin resistance, a proposed risk factor for certain cancers. Based on this prior knowledge, we tested pioglitazone and metformin individually and in combination for preventive efficacy in both rat (ER-positive) and mouse (ER-negative) mammary cancer models, using high-fat and high-fructose diets. Pioglitazone in both rats and mice at doses as high as 20 mg/kg BW/day, 7X/week was not toxic, although the high-fat diets resulted in weight gain. Rats: Pioglitazone alone in rats receiving a high-fat diet led to a 2% increase in mammary cancer multiplicity at a high dose (20 mg/kg BW/day) and a 21% decrease in multiplicity at a low dose (10 mg/kg BW/day). In rats fed a high-fructose diet, the combination of pioglitazone and metformin caused a 20% decrease in multiplicity, in contrast to pioglitazone alone which led to a 10% decrease in mammary cancer number. In rats fed a high-fat diet, the combination caused a 24% increase versus a 1.0% decrease in cancer multiplicity with pioglitazone alone. Mice: Pioglitazone alone at a high or low dose (20 or 10 mg/kg BW/day) in mice fed a high-fat diet resulted in a 28% and 47% reduction in mammary cancer multiplicity, respectively. In mice fed a high-fructose diet in a combination study, pioglitazone alone caused a 7% decrease in mammary cancer whereas the combination of pioglitazone with metformin showed no effect on mammary cancer reduction. Metformin alone in rats on a high-fat diet caused a 35% decrease in mammary cancer multiplicity at 150 mg/kg BW/day but a 9% decrease at 300 mg/kg BW/day. Metformin alone in rats on a high-fructose diet caused an 11% increase but the combination with pioglitazone caused a 20% decrease in cancer multiplicity. When rats were given a high-fat diet, metformin alone caused a 14% decrease and in combination with pioglitazone caused a 24% decrease in ER-positive mammary cancers. The conclusions are: (1) Pioglitazone is not active as a chemopreventive agent when given alone or in combination with metformin in rats treated with MNU on a high-fat or a high-fructose diet. (2) Pioglitazone is not active as a chemopreventive agent when given alone or in combination with metformin in MMTV/Neu mice treated with DMBA on a high-fat or a high-fructose diet. (3) Metformin is not active as a chemopreventive agent when given alone or in combination with pioglitazone in rats treated with MNU on a high-fat or a high-fructose diet. (4) Metformin showed some chemopreventive efficacy when given alone to MMTV/Neu mice receiving DMBA and on a high-fat diet. Efficacy was also observed with metformin alone and in combination with pioglitazone in mice receiving a high-fructose diet. Citation Format: Barbara K. Dunn, Chen Suen, Clinton Grubbs. Evaluation of the prevention by pioglitazone/metformin of ER-positive and ER-negative mammary cancers occurring in rodents on a high-fat diet [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1250.