Streptozotocin (STZ) diabetes enhances benzo(alpha)pyrene induced renal injury in Sprague Dawley rats

Characterization of a S1PR2 specific 11C-labeled radiotracer in streptozotocin-induced diabetic murine model

BACKGROUND

Diabetes mellitus is a chronic progressive metabolic disorder that affects millions of people worldwide. Emerging evidence suggests the important roles of sphingolipid metabolism in diabetes. In particular, sphingosine-1-phosphate (S1P) and S1P receptor 2 (S1PR2) have important metabolic functions and are involved in several metabolic diseases. In diabetes, S1PR2 can effectively preserve β cells and improve glucose/insulin tolerance in high-fat diet induced and streptozotocin (STZ)-induced diabetic mouse models. We previously developed a group of potent and selective S1PR2 ligands and radioligands.

METHODS

In this study, we continued our efforts and characterized our leading S1PR2 radioligand, [11C]TZ34125, in a STZ-induced diabetic mouse model. [11C]TZ34125 was radiosynthesized in an automated synthesis module and in vitro saturation binding assay was performed using recombinant human S1PR2 membrane. In vitro saturation autoradiography analysis was also performed to determine the binding affinity of [11C]TZ34125 against mouse tissues. Type-1 diabetic mouse model was developed following a single high dose of STZ in C57BL/6 mice. Ex vivo biodistribution was performed to evaluate the distribution and amount of [11C]TZ34125 in tissues. In vitro autoradiography analysis was performed to compare the uptake of [11C]TZ34125 between diabetic and control animals in mouse spleen and pancreas.

RESULTS

Our in vitro saturation binding assay using [11C]TZ34125 confirmed [11C]TZ34125 is a potent radioligand to recombinant human S1PR2 membrane with a Kd value of 0.9 nM. Saturation autoradiographic analysis showed [11C]TZ34125 has a Kd of 67.5, 45.9, and 25.0 nM to mouse kidney, spleen, and liver tissues respectively. Biodistribution study in STZ-induced diabetic mice showed the uptake of [11C]TZ34125 was significantly elevated in the spleen (~2 fold higher) and pancreas (~1.4 fold higher) compared to normal controls. The increased uptake of [11C]TZ34125 was further confirmed using autoradiographic analysis in the spleen and pancreases of STZ-induced diabetic mice, indicating S1PR2 can potentially act as a biomarker of diabetes in pancreases and inflammation in spleen. Future mechanistic analysis and in vivo quantitative assessment using non-invasive PET imaging in large animal model of diabetes is worthwhile.

CONCLUSIONS

Overall, our data showed an increased uptake of our lead S1PR2-specific radioligand, [11C]TZ34125, in the spleen and pancreases of STZ-induced diabetic mice, and demonstrated [11C]TZ34125 has a great potential for preclinical and clinical usage for assessment of S1PR2 in diabetes and inflammation.

Effects of sub-chronic, in vivo administration of sigma-1 receptor ligands on platelet and aortic arachidonate cascade in streptozotocin-induced diabetic rats

Background

Diabetes mellitus is a chronic metabolic disorder which induces endothelial dysfunction and platelet activation. Eicosanoids produced from arachidonic acid regulate cellular and vascular functions. Sigma-1 receptors (S1R) are expressed in platelets and endothelial cells and S1R expression is protective in diabetes.

Objectives

Our aim was to examine the influence of sub-chronic, in vivo administered S1R ligands PRE-084, (S)-L1 (a new compound) and NE-100 on the ex vivo arachidonic acid metabolism of platelets and aorta in streptozotocin-induced diabetic rats.

Methods

The serum level of the S1R ligands was detected by LC-MS/MS before the ex vivo analysis. Sigma-1 receptor and cyclooxygenase gene expression in platelets were determined by RT-qPCR. The eicosanoid synthesis was examined with a radiolabelled arachidonic acid substrate and ELISA.

Results

One month after the onset of STZ-induced diabetes, in vehicle-treated, diabetic rat platelet TxB2 and aortic 6-k-PGF1α production dropped. Sub-chronic in vivo treatment of STZ-induced diabetes in rats for one week with PRE-084 enhanced vasoconstrictor and platelet aggregator and reduced vasodilator and anti-aggregator cyclooxygenase product formation. (S)-L1 reduced the synthesis of vasodilator and anti-aggregator cyclooxygenase metabolites and promoted the recovery of physiological platelet function in diabetic rats. The S1R antagonist NE-100 produced no significant changes in platelet arachidonic acid metabolism. (S)-L1 decreased the synthesis of vasoconstrictor and platelet aggregator cyclooxygenase metabolites, whereas NE-100 increased the quantity of aortic vasodilator and anti-aggregator cyclooxygenase products and promoted the recovery of diabetic endothelial dysfunction in the aorta. The novel S1R ligand, (S)-L1 had similar effects on eicosanoid synthesis in platelets as the agonist PRE-084 and in aortas as the antagonist NE-100.

Conclusions

S1R ligands regulate cellular functions and local blood circulation by influencing arachidonic acid metabolism. In diabetes mellitus, the cell-specific effects of S1R ligands have a compensatory role and aid in restoring physiological balance between the platelet and vessel.

A study on toxicity and anti-hyperglycemic effects of Abhrak Bhasma in rats

Background

Abhrak bhasma (AB) is widely used in the treatment of diabetes mellitus (DM); however, no scientific study is reported till date on its efficacy and safety to prove it's pharmacological effects. Streptozotocin (STZ) is a gulcosamine–nitrosourea complex produced by Streptomyces achromogenes, which particularly induces DNA strand breakage in pancreatic β-cells causing DM. The damage caused by STZ to pancreatic β-cells is coupled with insulin release in the initial stage, subsequently leading to hyperglycemia owing to insulin deficiency.

Objective(s)

In the present study, the safety and effectiveness of AB was evaluated by invivo acute and sub-acute toxicity study and STZ-induced hyperglycemic activity in rats.

Materials and methods

Acute oral toxicity assessed as per OECD 425 guidelines by employing up-down procedure (UDP), sub-acute toxicity as per OECD-407 guidelines and anti-hyperglycemic activity using STZ method. The anti-hyperglycemic potential of AB in rats (40, 80, and 160 mg/kg body weight (b.w.)) was evaluated by determining the body weight, blood glucose, organ weight, lipid profile, and histo-morphological and histo-pathological investigations.

Results

The highest tolerated dose of AB was 2000 mg/kg b.w., and sub-acute toxicity of different AB doses showed no significant variation, when compared with the control. Interestingly, a noteworthy reduction in blood glucose, total cholesterol, and triglycerides levels were observed in AB-treated diabetic rats, along with a considerable increase in body weight, when compared with those noted in the disease control and normal control.

Conclusion

Effectiveness of AB as a potential safe and potent candidate for the treatment of diabetes was revealed as compared to the standard drug Metformin by STZ-induced method.

Environmental pollution and diabetes mellitus

Diabetes mellitus (DM) is a chromic metabolic disease that affects a large segment of the population worldwide. Physical inactivity, poor nutrition, and genetic predisposition are main risk factors for disease development. In the last decade, it was clear to the scientific community that DM development is linked to a novel disease inducer that was later defined as diabetogenic factors of pollution and endocrine disrupting agents. Environmental pollution is exponentially increasing in uncontrolled manner in several countries. Environmental pollutants are of diverse nature and toxicities, including polyaromatic hydrocarbons (PAHs), pesticides, and heavy metals. In the current review, we shed light on the impact of each class of these pollutants and the underlined molecular mechanism of diabetes induction and biological toxicities. Finally, a brief overview about the connection between coronavirus disease 2019 and diabetes pandemics is presented.

Antidiabetic and antihyperlipidemic effects of aqueous extract of Parquetina nigrescens in streptozotocin-nicotinamide induced type 2 diabetic rats

Background

Parquetina nigrescens is among the evergreen plants native to West Africa. It is used in the management of various ailments including anemia, fever, asthma and diabetes. This study evaluated the antidiabetic and antihyperlipidemic effect of Parquetina nigrescens in streptozotocin-nicotinamide-induced type 2 diabetic rats.

Methods

Type 2 diabetes mellitus was induced in overnight fasted rats with a single intraperitoneal injection of streptozotocin (60 mg/kg), followed by the administration of nicotinamide (120 mg/kg) after an interval of 15 min. Diabetic rats were orally administered with; 200, 400 and 800 mg/kg of aqueous extract of Parquetina nigrescens (AEPN), metformin (180 mg/kg) and glibenclamide (1 mg/kg) for two weeks. The effect of treatments on fasting blood glucose, serum insulin, leptin, adiponectin, homa-ir, lipid profile, body weight, pancreatic antioxidants parameters, hepatic glycogen content, glucose-6-phosphate activity, α-amylase inhibition, α-glucosidase inhibition, lipase inhibition and histology of the organs were evaluated.

Results

Data from this study showed that treatment with AEPN produced a significant reduction (p < 0.05) in fasting blood glucose, glucose-6-phosphatase activity, serum lipase, total triglyceride, total cholesterol, low-density lipoproteins, very low-density lipoprotein, atherogenic index, coronary risk index, pancreatic α-amylase, α-glucosidase and lipase activities. Treatment with AEPN also produced a significant (p < 0.05) increase in; glucose tolerance, glycogen content, leptin, adiponectin and pancreatic antioxidants (glutathione, superoxide dismutase, catalase and high-density lipoproteins). The histology of the organ showed regeneration of the pancreatic tissue after treatment with AEPN.

Conclusions

This study showed that AEPN exhibited antidiabetic and antihyperlipidemic activity in streptozotocin-nicotinamide-induced type 2 diabetic rats.

Modulatory effects of catechin hydrate on benzo[a]pyrene-induced nephrotoxicity in adult male albino rats

Benzo [a] pyrene (B[a]P) is a potent mutagen and carcinogen, considered one of the commonest concomitants in the environment. The study aimed to evaluate the effect of catechin hydrate on benzo pyrene-induced kidney toxicity. Thirty-six adult male albino rats were divided into six groups: group I untreated control, group II received 10 mL/kg of corn oil (solvent of benzo [a] pyrene) twice a week, group III received 1 mL/kg 0.5% dimethyl sulfoxide (DMSO) (solvent of catechin) once per day, group IV received 50 mg/kg body weight of benzo[a]pyrene twice a week, group V received 20 mg/kg body weight of catechin in 1 mL/kg 0.5% DMSO once daily, and group VI received both catechin+benzo [a] pyrene with the same doses. All treatment was given by oral gavage for four weeks. At the end of the experiment, blood samples were collected for biochemical investigations, tissues were obtained for genotoxicity, RT-PCR, and histopathological studies. B[a]P exposure induced an increase in serum urea and creatinine levels along with severe renal histopathological changes. Our results showed a subsequent decrease in the antioxidant enzyme activities (catalase and superoxide dismutase), and conversely, (malondialdehyde) levels markedly elevated. Also, B[a]P induced DNA damage as well as activated an apoptotic pathway confirmed by upregulation of Bax, caspase-3, and downregulation of Bcl-2 expression. However, treatment with catechin-corrected kidney functions and antioxidant enzymes as well as regulated apoptosis. Histological results also supported the protective effects of catechin. These findings suggested that catechin hydrate is an effective natural product that attenuates benzo pyrene-induced kidney toxicity.

Alpha-1 antitrypsin suppresses macrophage activation and promotes islet graft survival after intrahepatic islet transplantation

Alpha-1 antitrypsin (AAT) has protective functions in animal islet transplantation models. While the therapeutic effect of AAT therapy is currently being tested in clinical trials, we investigated the mechanism of AAT protection in a clinically relevant marginal intrahepatic human islet transplantation model. In recipients receiving islets and AAT, 68.9% (20/29) reached normoglycemia, compared to 35.7% (10/28) in those receiving islets only, at 60 days posttransplant (PT). AAT-treated mice had lower serum levels of inflammatory cytokines immediately PT. Reduced M1 macrophages were observed in livers of AAT-treated recipients compared to controls as evidenced by flow cytometry and RNA-seq transcriptional profiling analysis. In vitro AAT suppressed IFN-γ-induced M1 macrophage activation/polarization via suppression of STAT1 phosphorylation and iNOS production. AAT inhibits macrophage activation induced by cytokines or dying islets, and consequently leads to islet cell survival. In a macrophage depletion mouse model, the presence of M1 macrophages in the liver contributed to graft death. AAT, through suppressing macrophage activation, protected transplanted islets from death and dysfunction in the human islet and NOD-SCID mouse model. The protective effect of AAT was confirmed in a major mismatch allogeneic islet transplantation model. Taken together, AAT suppresses liver macrophage activation that contributes to graft survival after transplantation.

Effects of benzo(a)pyrene at environmentally relevant doses on embryo-fetal development in rats

Studies have demonstrated that Benzo(a)Pyrene (BaP), a polycyclic aromatic hydrocarbon ubiquituous in the environment, can cause teratogenic effects. Since the majority of studies used in vitro models or high doses of BaP, this study evaluated the teratogenicity, reproductive and developmental performance of low doses of BaP through maternal and fetus examination after daily oral administration of BaP (0; 0.1; 1.0 or 10 μg/kg) to pregnant Wistar rats from Gestational day (GD) 6 to GD 15 (the organogenesis period). Pregnant rats did not exhibit clinical signs of toxicity during the exposure period. However, dams exposed to the lowest dose of BaP showed a reduction in the erythrocytes number and in the creatinine levels. The groups exposed to 0.1 and 1.0 μg/kg presented a decrease in placental efficiency, as well as an increase in placental weight. After fetal examination, the treated group with the lowest dose showed a reduced relative anogenital distance, while the curve of normal distribution of weight was changed in the highest dose group. In addition, anomalies evidenced by changes in the renal size and degree of fetal ossification were observed in treated-fetus. In conclusion, treatment with BaP during organogenesis at this dose level is detrimental to the normal development of fetuses.

Pregnancy environment, and not preconception, leads to fetal growth restriction and congenital abnormalities associated with diabetes

Maternal diabetes can lead to pregnancy complications and impaired fetal development. The goal of this study was to use a mouse model of reciprocal embryo transfer to distinguish between the preconception and gestational effects of diabetes. To induce diabetes female mice were injected with a single high dose of streptozotocin and 3 weeks thereafter used as oocyte donors for in vitro fertilization (IVF) and as recipients for embryo transfer. Following IVF embryos were cultured to the blastocyst stage in vitro or transferred to diabetic and non-diabetic recipients. Diabetic and non-diabetic females did not differ in regard to the number of oocytes obtained after ovarian stimulation, oocytes ability to become fertilized, and embryo development in vitro. However, diabetic females displayed impaired responsiveness to superovulation. Reciprocal embryo transfer resulted in similar incidence of live fetuses and abortions, and no changes in placental size. However, fetuses carried by diabetic recipients were smaller compared to those carried by non-diabetic recipients, regardless hyperglycemia status of oocyte donors. Congenital abnormalities were observed only among the fetuses carried by diabetic recipients. The findings support that the diabetic status during pregnancy, and not the preconception effect of diabetes on oogenesis, leads to fetal growth restriction and congenital deformities.

Evaluation of renal markers of T1D in Sprague-Dawley exposed to 2-aminoanthracene

The incidence of type 1 diabetes (T1D) and its associated risks of chronic kidney disease or end-stage renal disease development are on the rise. T1D is an autoimmune disease in which insulin-producing beta cells are destroyed. Increased incidence of T1D has been suggested to be a result of environmental factors such as exposure to polycyclic aromatic hydrocarbons (PAHs). 2-aminoanthracene (2AA) is a PAH that has been associated with the onset of early diabetic symptoms. This study was conducted to assess if 2AA dietary ingestion would induce T1D renal injuries. To accomplish study goals, Sprague-Dawley rats were assigned into three 2AA dietary (0, 50, and 100 mg/kg-2AA) ingestion groups for 12 weeks. Animals were evaluated for various morphometric indices, clinical markers, and gene expression. The rats in the 100 mg/kg group lost 5% less weight than the other treatment groups and converted roughly 3% more of their food intake into body mass. Renal histopathology indicated no significant difference between groups. The kidney weight per bodyweight of the 100 mg/kg treatment group was 30.1% greater than the control group. Creatinine concentration of the 100 mg/kg group was 46.2% greater than the control group. Serum glucose levels were significantly elevated in rats exposed to 2AA. On the contrary, serum albumin concentration was significantly reduced in 2AA-treated rats. T1D and genetic markers of renal injury such as FABP1, SPP1, IL-1B, and IL-7 were elevated in treated groups. These results suggest that 2AA may induce the early diabetic renal injuries.

Acute benzo[a]pyrene treatment causes different antioxidant response and DNA damage in liver, lung, brain, stomach and kidney

Acute effects of oxidative damage induced by benzo[a]pyrene (B[a]P) on various organs are still not clear. In this study, we investigated oxidative stress and DNA damage in liver, lung, stomach, brain and kidney of ICR male mice induced by acute B[a]P treatment. B[a]P treatment led to a significant decrease at the different doses in body weight. For the variations of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) and GSH/GSSG, significant increases were observed at 24 h, then decreased till 72 h after B[a]P injection. The increase percent indicated in a dose- dependent decrease manner. However, glutathione peroxidase (GPx), GSSG and MDA were significantly increased in a time- and dose-dependent increase manner. DNA damage showed the significant and top levels at 24 h, and increased in proportion to the doses of B[a]P treatment. The total induction could be indicated by the variation of MDA at 24 h after B[a]P injection and showed the following order of predominance: lung > liver > kidney = stomach > brain. This was further certificated by histopathological changes in the examined organs. Additionally, the levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and blood urea nitrogen (UN), creatinine were also significantly increased at 24 h after B[a]P injection. These findings suggested the disturbance of antioxidant responses and aggravation of DNA damages, and the different responses on various organs induced by acute B[a]P treatment in organism.

Protective Effects of Ursolic Acid in the Kidneys of Diabetic Rats

Objectives

Diabetes, a heteregenous metabolic and chronic disease, is a growing health problem in most countries. It has been claimed that diabetes is associated with the increased formation of free radicals and decreased in antioxidant potential. Oxidative stress formed in diabetes may cause DNA damage in the tissues. Ursolic acid, a well-known pentacylic triterpene, is commonly used in traditional Chinese medicine due to its beneficial health effects such as antioxidant, anticancer, and antiulcer properties. The aim of this study was to investigate the effects of ursolic acid in the kidneys of Wistar albino rats with streptozotocin-induced diabetes.

Materials and Methods

DNA damage was evaluated in the kidney cells of rats using alkaline comet assays. Oxidative stress parameters such as CAT, SOD, GR, and GSH-Px enzyme activities and total GSH and MDA levels were also evaluated.

Results

Ursolic acid treatment was found to significantly decrease DNA damage, GR enzyme activities, and MDA levels, and significantly increase GSH levels and CAT, SOD and GSH-Px enzyme activities in diabetic rats.

Conclusion

According to our results, it seems that ursolic acid may be beneficial against diabetes-induced renal damage.

Effects of kisspeptin on diabetic rat platelets

Hyperglycemia, hyperlipidemia, and free radicals result in platelet activation and atherogenesis. Kisspeptin (KP) is able to regulate metabolism, hemostasis, and the development of atherosclerosis. We examined whether platelet aggregation of streptozotocin-induced diabetic rats depends on the inducer type and if KP-13 and RF-9 (a kisspeptin receptor modifier) can influence platelet function. We measured the speed and the maximum of aggregation, along with the area under the curve. Serum glucose and calcium levels and urine formation of diabetic animals increased, while the body mass and platelet count decreased. Collagen was the most effective inducer of platelet aggregation. The aggregability of nondiabetic platelets was elevated in the presence of 5 × 10−8 mol/L KP-13. This effect was less expressed in diabetic animals. The effectivity of RF-9 was stronger than that of KP-13 in nondiabetic platelets, however it was ineffective in diabetic animals. RF-9 pre-treatment did not change the effects of 5 × 10−8 mol/L KP-13 in either animal group. The in vivo activation of diabetic platelets, which may be due to elevated serum calcium, induces thrombocytopenia and may lead to reduced in vitro aggregability. We could not demonstrate the antagonistic effect of RF-9 against KP-13 in isolated platelets.

Hpyerglycemic and anti-diabetic nephritis activities of polysaccharides separated from Auricularia auricular in diet-streptozotocin-induced diabetic rats

Due to substantial morbidity and complications including nephropathy, a search for alternative treatment of diabetes mellitus is urgently required. The present study aimed to investigate the hypoglycemic and anti-diabetic nephropathy activities of polysaccharides separated from Auricularia auricular (AAP). Diet streptozotocin (STZ)-induced diabetic Sprague-Dawley rats were orally treated with metformin (100 mg/kg; positive control) and AAP (100 and 400 mg/kg) for four weeks, and parameters in the serum and liver associated with blood glucose, free radicals and nephropathy were determined. Similar to metformin, AAP treatment strongly reduced blood glucose levels by promoting glucose metabolism. The anti-oxidative activity of AAP, which was indicated by the modulation of superoxide dismutase, glutathione peroxidase, reactive oxygen species and methane dicarboxylic aldehyde levels in serum, was observed in diabetic rats. Furthermore, the regulatory effects of AAP on blood urea nitrogen, creatinine, uric protein and inflammatory-related factors revealed its protection against diabetic nephropathy. The present data suggests that AAP-mediated anti-diabetic and anti-nephritic effects are partially associated with their modulations on the anti-oxidative system and nuclear factor kappa B-related signaling pathway. In conclusion, AAP has potential to be a novel source of treatments for diabetes.

Studies on the antidiabetic activities of Cordyceps militaris extract in diet-streptozotocin-induced diabetic Sprague-Dawley rats

Due to substantial morbidity and high complications, diabetes mellitus is considered as the third “killer” in the world. A search for alternative antidiabetic drugs from herbs or fungi is highly demanded. Our present study aims to investigate the antidiabetic activities of Cordyceps militaris on diet-streptozotocin-induced type 2 diabetes mellitus in rats. Diabetic rats were orally administered with water extract or alcohol extract at 0.05 g/kg and 2 g/kg for 3 weeks, and then, the factors levels related to blood glucose, lipid, free radicals, and even nephropathy were determined. Pathological alterations on liver and kidney were examined. Data showed that, similar to metformin, Cordyceps militaris extracts displayed a significant reduction in blood glucose levels by promoting glucose metabolism and strongly suppressed total cholesterol and triglycerides concentration in serum. Cordyceps militaris extracts exhibit antioxidative effects indicated by normalized superoxide dismutase and glutathione peroxidase levels. The inhibitory effects on blood urea nitrogen, creatinine, uric acid, and protein revealed the protection of Cordyceps militaris extracts against diabetic nephropathy, which was confirmed by pathological morphology reversion. Collectively, Cordyceps militaris extract, a safe pharmaceutical agent, presents excellent antidiabetic and antinephropathic activities and thus has great potential as a new source for diabetes treatment.

Review of the mechanism of cell death resulting from streptozotocin challenge in experimental animals, its practical use and potential risk to humans

Streptozotocin (STZ) (2-deoxy-2-({[methyl(nitroso)amino]carbonyl}amino)-β-D-glucopyranose) is a naturally occurring diabetogenic compound, produced by the soil bacterium streptomyces achromogenes, that exhibits broad spectrum of antibacterial properties. Streptozotocin functions as a DNA synthesis inhibitor in both bacterial and mammalian cells. In mammalian cells, the actual mechanism and metabolic targets of STZ toxicity that results in cell death is not known. This review identifies four key areas that explain the mechanism of the cytotoxicity of STZ in mammalian cell lines, investigates the practical aspects of using STZ in experimental animals and the potential risks of its exposure to human health.

Evaluation of antidiabetic potential of selected traditional Chinese medicines in STZ-induced diabetic mice

AIMS

Traditional Chinese medicine (TCM) has been used for treating complex chronic diseases owing to their fewer side-effects, better patient tolerance and relatively less cost. The present work was carried out to study the anti-diabetic efficacy and mechanisms of 34 TCMs.

MATERIALS AND METHODS

Streptozotocin (STZ)-diabetic mice were orally administrated with corresponding herbal solution once a day for 4 weeks. At the end of experiment, the level of plasma glucose, malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and the serum aldose reductase (AR) were determined, the effects of TCM extract on α-glucosidase and angiotensin-converting enzyme (ACE) in vitro were also evaluated.

RESULTS

13 out of the 34 herbs showed a statistically significant plasma glucose lowering action compared with the diabetic control group. Biochemical analysis revealed that Atractylodes macrocephala, Codonopsis pilosula, Dioscorea opposite, Flos lonicerae and Pueraria lobata may retard the progression of diabetes via reduce the blood glucose level and prevent the increase of AR activity. Other tested herbs, such as Ramulus cinnamomi, Cinnamomum cassia, and Eucommia ulmoides, showed the antidiabetic ability by either prevent the decrease in SOD activity or suppress the increase of MDA. Zymologic assay reveals that Pueraria lobata and Anemarrhena asphodeloides showed the highest inhibition against α-glucosidase and ACE respectively. Interestingly, the post-treatment glucose levels and AR activity were positively correlated with kidney/body weight of 34 herbs treated diabetic mice (p = 0.02, 0.04 respectively).

CONCLUSIONS

Several potential antidiabetic herbs derived from Chinese traditional pharmacopeia such as Dioscorea opposite, Pueraria lobata, Codonopsis pilosula and Ramulus cinnamomi, have been found to exert a beneficial action on diabetes and diabetic complications via multi-mechanisms.

Antidiabetic potential of α-amylase inhibitor from the seeds of Macrotyloma uniflorum in streptozotocin-nicotinamide-induced diabetic mice

CONTEXT

Macrotyloma uniflorum (Lam.) Verdc. (Leguminosae) seeds, known as the poor man's pulse crop in India, have been used as a food and also used in the traditional method for treatment of kidney stones, diabetes, obesity, etc.

OBJECTIVE

To investigate the antidiabetic effect of α-amylase inhibitor isolated from the seeds of Macrotyloma uniflorum seeds in streptozotocin-nicotinamide induced diabetic mice.

MATERIALS AND METHOD

α-Amylase inhibitor was purified using a carboxymethyl cellulose (CMC) column. Kinetic studies were done using mouse pancreatic and human salivary α-amylase. Its antidiabetic effect was studied in streptozotocin-nicotinamide-induced diabetic mice. Biochemical parameters such as serum total cholesterol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined. Histopathological investigation was performed on the pancreas, kidney, and liver tissue samples.

RESULTS

Macrotyloma uniflorum α-amylase inhibitor (MUAI) inhibited both the mouse pancreatic and human salivary α-amylase in a non-competitive manner with K(i) values of 11 and 8.8 µM and IC(50) value of 30 and 12.5 µg/mL, respectively. It decreased the serum glucose level in the treated diabetic mice. Histological findings suggested minimum pathological changes in the treated diabetic mice as compared to the diabetic control.

DISCUSSION AND CONCLUSION

The results suggest that MUAI has an antihyperglycemic activity and therefore can be used in the dietary treatment of non-insulin dependent diabetes mellitus.

Inducible nitric oxide synthase-mediated decrease of intestinal P-glycoprotein expression under streptozotocin-induced diabetic conditions

AIMS

P-glycoprotein (P-gp), one of the important drug-efflux pumps, is known to be affected by pathological conditions such as inflammation or infection. Recently, it is reported that high glucose or hyperglycemia can alternate P-gp expression levels at the blood-brain barrier or in the kidney, although the details are still unknown. Here, we analyzed the alteration of intestinal P-gp expression and function in the development of diabetes and elucidated the mechanisms.

MAIN METHODS

Type 1 diabetes was induced in male ddY mice by an i.p. injection of streptozotocin (STZ) (230 mg/kg). We analyzed ileal P-gp expression and function using Western blot analysis and an in situ closed loop method, respectively.

KEY FINDINGS

A significant reduction of P-gp expression level in ileum was found 9 days after STZ administration. In contrast, a remarkable decrease in P-gp function was observed on the 3rd and 9th days. Interestingly, nitric oxide synthase (NOS) activity in ilea was significantly increased on the 9th day. The decrease of P-gp expression levels observed on the 9th day was completely suppressed by L-N(G)-nitroarginine methyl ester (L-NAME), a broad range NOS inhibitor, or aminoguanidine, a specific inducible NOS (iNOS) inhibitor.

SIGNIFICANCE

These results indicate the possibility that nitric oxide (NO), produced by iNOS in the ileum, is involved in the reduction of ileal P-gp expression under STZ-induced diabetic conditions.

Genetic regulatory networks of nephrogenesis: deregulation of WT1 splicing by benzo(a)pyrene

Recent studies have identified AHR as a master regulator of Wilms' tumor suppressor gene (WT1) signaling in the developing kidney. Activation of AHR signaling by environmental chemical is associated with proteasome-mediated degradation of AHR protein, disruption of WT1 alternative splicing, and marked alterations in the regulation of genetic programs of developmental progression in the developing kidney. The complexity of genetic regulatory networks of nephrogenesis controlled by AHR-WT1 interactions will be discussed here with particular emphasis given to the biological and medical consequences that may result from deficits in nephrogenesis that compromise reserve capacity and renal function later in life. Understanding the impact of early-life environmental exposures to chemicals that disrupt AHR signaling can help minimize negative health consequences to pregnant women and their offspring.

Diabetes and hypertriglyceridemia modify the mode of acetaminophen-induced hepatotoxicity and nephrotoxicity in rats and mice

Certain disease conditions can modify drug-induced toxicities, which, in turn, may cause a medication-related health crisis. Therefore, preclinical investigations into the alterations in drug-induced toxicities using appropriate disease animal models are very important. This paper reviews the reported data related to the effects of diabetes and hypertriglyceridemia, common lifestyle-related diseases in a modern society, on acetaminophen (APAP)-induced hepatotoxicity and nephrotoxicity in rats and mice. It has generally been reported that diabetes protects rats and mice from APAP-induced hepatotoxicity and there are several reports that help to speculate on the effects of diabetes on APAP-induced nephrotoxicity. In fructose-induced hypertriglyceridemic rats, hepatotoxicity of APAP becomes apparently less severe, whereas nephrotoxicity of APAP becomes significantly more severe. The mechanisms of alteration of APAP-induced hepatorenal toxicity under diabetic and hypertriglyceridemic conditions are also discussed in this paper.

The effect of doxorubicin on rats that received toxic and carcinogenic benzo(a)pyrene

Benzo(a)pyrene (B(a)P) is a polycyclic aromatic hydrocarbon with carcinogenic and toxic effects. Doxorubicin is a DNA-interacting drug widely used in chemotherapy. In the present study we investigated the effects of doxorubicin on rats that received benzo(a)pyrene. Sprague-Dawley male rats, 3-4 months old, were divided into 5 groups (n=9 per group). Group 1 (controls) received normal saline intraperitoneally (i.p.) and intragastrically (i.g.), Group 2 (controls) similarly received corn oil i.p. and i.g., Group 3 received corn oil soluble benzo(a)pyrene (10mg/kg b.wt every 10 days for 40 days), Group 4 received doxorubicin (4 mg i.p. on 3 consecutive days), Group 5 received doxorubicin for 3 days (as in group 4) followed by benzo(a)pyrene as in group 3. After twenty-four hours urine samples were collected, heart blood, liver and kidney tissue samples were obtained. Biochemical data were evaluated on urine and blood; liver and kidney tissue samples were investigated histologically. Uric acid, urine creatinine, creatine clearance, urea nitrogen, serum creatinine values, serum glutamic oxaloacetic transaminase (SGOT, AST), serum glutamic pyruvic transaminase (SGPT, ALT), alkaline phosphatase (ALP, AP), superoxide dismutase (SOD), catalase (CAT) activities and malondialdehyde (MDA) levels were significantly different in the 3rd group compared with control groups. Most of the parameters group 5 were statistically similar to control values. Histological appearance of the liver and the kidney tissue samples supported the improvement in the 5th group. The result of our study indicated that liver and kidney functions impaired with benzo(a)pyrene may be partially restored by doxorubicin.

Renal protective activity of Hsian-tsao extracts in diabetic rats

OBJECTIVE

To investigate the renal protective activity of Hsian-tsao Mesona procumbens Hemsl. water extracts in diabetic rats.

METHODS

Thirty Sprague-dawley female rats were randomly divided into three groups (n = 10 each), "control group" with intraperitoneal saline injection, "diabetic group" with 60 mg of intraperitoneal streptozotocin injection per kg of body weight and "Hsian-tsao group" with intragastric administration of Hsian-tsao extraction everyday for 4 weeks after intraperitoneal streptozotocin injection. The body weight and blood sugar were measured before and after model induction in the three groups. Thrombospondin-1 (TSP-1) expressions in the kidney were monitored by immunohistochemistry. Kidney ultrastructural changes were also analyzed by using transmission electron microscopy.

RESULTS

Before diabetic model induction, there were no significant differences among the three groups in body weight and blood sugar. Four weeks after the induction of diabetes, the differences became statistically significant. Electron microscopy also revealed disruption of the foot processes of the podocytes and other damages in diabetic group. These damages were significantly less severe in Hsian-tsao group when compared with the diabetic group. TSP-1 expressions in the kidney were significantly increased in both the diabetic group and Hsian-tsao group, but it was relatively lower in Hsian-tsao group than in diabetic group.

CONCLUSION

Our results showed that Hsian-tsao treatment in the diabetic rats effectively prevented the pathological alterations in the kidney and decreased the TSP-1 expression. It was suggested that Hsian-tsao had protective effect on the kidneys of the diabetic rats.

Animal models to test drugs with potential antidiabetic activity

Although medicinal plants have been historically used for diabetes treatment throughout the world, few of them have been validated by scientific criteria. Recently, a large diversity of animal models has been developed to better understand the pathogenesis of diabetes mellitus and new drugs have been introduced in the market to treat this disease. The aim of this work was to review the available animal models of diabetes and some in vitro models which have been used as tools to investigate the mechanism of action of drugs with potential antidiabetic properties. In addition, a MEDLINE/PUBMED search for articles on natural products, pancreatectomy and diabetes mellitus treatment published between 1996 and 2006 was done. In the majority of the studies, natural products mainly derived from plants have been tested in diabetes models induced by chemical agents. This review contributes to the researcher in the ethnopharmacology field to designs new strategies for the development of novel drugs to treat this serious condition that constitutes a global public health.

Modification of inherent and drug-induced dopaminergic activity after exposure to benzo(alpha)pyrene

The aim of this study was to investigate the effect of benzo(alpha)pyrene (B(alpha)P), a representative polycyclic aromatic hydrocarbon (PAH), on dopaminergic activity in brain. (B(alpha)P) altered dopaminergic activity in discrete regions of the rat brain, including the hippocampus, hypothalamus, caudate putamen and nucleus accumbens. Specifically, B(alpha)P increased DA levels in the hippocampus and DA turnover in the caudate putamen. In addition, B(alpha)P suppressed DA levels in the caudate putamen and DA turnover in the nucleus accumbens. B(alpha)P also altered the effect of several dopaminergic agents, L-DOPA, sulpiride and bromocriptine, on DA activity. In particular, B(alpha)P enhanced the L-DOPA-induced increase in the DA turnover ratio in the caudate putamen and increased DA levels in the nucleus accumbens. B(alpha)P also reversed the sulpiride-induced increase of DA turnover in the nucleus accumbens and the bromocriptine-induced increase of DA turnover in the hippocampus. In addition, DA turnover was increased by B(alpha)P in the nucleus accumbens and caudate putamen and DA levels were suppressed in the nucleus accumbens of bromocriptine treated rats, though the drug alone had no effect. These changes indicate that exposure to B(alpha)P and related compounds may affect dopaminergic function in discrete brain regions that are implicated in cognitive functions, psychosis, depression and Parkinson's disease, and may possibly interfere with their pharmacological intervention.