Anti-Diabetic Effects of the Ethyl-Acetate Fraction of Trichilia catigua in Streptozo-tocin-Induced Type 1 Diabetic Rats

Melatonin downregulates the increased hepatic alpha-fetoprotein expression and restores pancreatic beta cells in a streptozotocin-induced diabetic rat model: a clinical, biochemical, immunohistochemical, and descriptive histopathological study

Background

Diabetes mellitus (DM) is a chronic metabolic disorder. Hepatopathy is one of the serious effects of DM Melatonin (MT) is a potent endogenous antioxidant that can control insulin output. However, little information is available about the potential association between melatonin and hepatic alpha-fetoprotein expression in diabetes.

Objective

This study was conducted to assess the influence of MT on diabetes-related hepatic injuries and to determine how β-cells of the pancreas in diabetic rats respond to MT administration.

Materials and methods

Forty rats were assigned to four groups at random (ten animals per group). Group I served as a normal control group. Group II was induced with DM, and a single dose of freshly prepared streptozotocin (45 mg/kg body weight) was intraperitoneally injected. In Group III, rats received 10 mg/kg/day of intraperitoneal melatonin (IP MT) intraperitoneally over a period of 4 weeks. In Group IV (DM + MT), following the induction of diabetes, rats received MT (the same as in Group III). Fasting blood sugar, glycosylated hemoglobin (HbA1c), and serum insulin levels were assessed at the end of the experimental period. Serum liver function tests were performed. The pancreas and liver were examined histopathologically and immunohistochemically for insulin and alpha-fetoprotein (AFP) antibodies, respectively.

Results

MT was found to significantly modulate the raised blood glucose, HbA1c, and insulin levels induced by diabetes, as well as the decreased alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Furthermore, MT attenuated diabetic degenerative changes in the pancreas and the hepatic histological structure, increased the β-cell percentage area, and decreased AFP expression in the liver tissue. It attenuated diabetes-induced hepatic injury by restoring pancreatic β-cells; its antioxidant effect also reduced hepatocyte injury.

Conclusion

Collectively, the present study confirmed the potential benefits of MT in downregulating the increased hepatic alpha-fetoprotein expression and in restoring pancreatic β-cells in a streptozotocin-induced diabetic rat model, suggesting its promising role in the treatment of diabetes.

Short chain fatty acids, a possible treatment option for autoimmune diseases

Gut microbiota can interact with the immune system through its metabolites. Short-chain fatty acids (SCFAs), as one of the most abundant metabolites of the resident gut microbiota play an important role in this crosstalk. SCFAs (acetate, propionate, and butyrate) regulate nearly every type of immune cell in the gut's immune cell repertoire regarding their development and function. SCFAs work through several pathways to impose protection towards colonic health and against local or systemic inflammation. Additionally, SCFAs play a role in the regulation of immune or non-immune pathways that can slow the development of autoimmunity either systematically or in situ. The present study aims to summarize the current knowledge on the immunomodulatory roles of SCFAs and the association between the SCFAs and autoimmune disorders such as celiac disease (CD), inflammatory bowel disease (IBD), rheumatoid arthritis (RA), multiple sclerosis (MS), systemic lupus erythematosus (SLE), type 1 diabetes (T1D) and other immune-mediated diseases, uncovering a brand-new therapeutic possibility to prevent or treat autoimmunity.

Insight into the hepatoprotective, hypolipidemic, and antidiabetic impacts of aliskiren in streptozotocin-induced diabetic liver disease in mice

BACKGROUND

Diabetic hepatopathy is a serious complication of poorly controlled diabetes mellitus. An efficient antidiabetic drug which keeps normal liver tissues is not available. The renin-angiotensin system has been reported to be involved in both diabetic state and liver function. Aliskiren is a direct renin inhibitor and a recently antihypertensive drug with poly-pharmacological properties. The aim of the current study is to explore the possible hepatoprotective effects and mechanisms of action of aliskiren against streptozotocin (STZ) induced liver toxicity.

METHODS

Mice were distributed to 3 groups; first: the normal control group, second: the diabetic control group, third: the diabetic group which received aliskiren (25 mg/kg; oral) for 4 weeks. At the end of the treatment period, plasma glucose, insulin, lipid profile, oxidative stress, and liver function tests were evaluated spectrophotometrically. ELISA technique was used to measure the expression levels of TNF-α and adiponectin. Furthermore, a Histopathological examination of liver samples was done.

RESULTS

It was shown that aliskiren treatment ameliorated the STZ-induced oxidative stress and elevated inflammatory biomarkers, hypercholesterolemia, serum aminotransferases and alkaline phosphatase levels in diabetic mice. In addition, hepatocellular necrosis, and fibrosis were improved by aliskiren treatment.

CONCLUSION

aliskiren protects against the liver damage caused by STZ-induced diabetes. This can be explained by its ability to block angiotensin-II, and its anti-diabetic, hypocholesterolemic, antioxidant and anti-inflammatory effects. Aliskiren could be a novel therapeutic strategy to prevent liver diseases associated with hypertension and diabetes mellitus.

Whey protein enriched with Stevia rebaudiana fraction restores the pancreatic function of streptozotocin induced diabetic rats

The study aims to analyse the treatment of whey protein enriched with Stevia rebaudiana fraction in insulin secretion and its role mitigating streptozotocin-induced hyperglycemia in rats. Thus, diabetic animals were treated with whey protein enriched with S. rebaudiana fraction or with only the protein isolate or only the Stevia fraction. Insulin level in plasma was measured by radioimmunoassay and the viability of β cells was detected by immunohistochemistry. The results showed that diabetic animals treated with whey protein enriched with S. rebaudiana fraction had a greater recovery from insulinemia, with plasma levels similar to non-diabetic animals (~ 0.13 ng/mL). In addition, the same group showed a higher number of insulin-positive pancreatic B cells (~ 66%) in immunohistochemistry analysis, while the diabetic groups treated with only the fraction of stevia or whey protein showed 38 and 59% of positive cells, respectively. These results show that the treatment may have restored the viability of streptozotocin-injured pancreatic B cells, and consequently increased insulin secretion, suggesting whey protein enriched with S. rebaudiana fraction can be used an adjunct/supplement in diabetic treatment.

Identification and characterization of anti-diabetic principle in Senna alata (Linn.) flower using alloxan-induced diabetic male Wistar rats

ETHNO-PHARMACOLOGICAL RELEVANCE

The age-long folkloric use of Senna alata flower (SAF) was recently substantiated with scientific evidence. However, the study did not account for the anti-diabetic principle(s) in SAF.

AIM OF THE STUDY

The study aimed to identify and characterize the bioactive principle(s) responsible for the anti-diabetic activity in SAF.

MATERIALS AND METHODS

Ninety-one male Wistar rats were used for the two phases of this study. In phase 1, forty-two of these were allotted into six groups (A-F) of seven rats each. Animals in group A received distilled water while those in groups B-F were made diabetic by treatment with 150 mg/kg body weight (b.w.) of alloxan. Group B received 0.5 mL of distilled water; C, D and E were treated each with 75 mg/kg b.w. of ethyl acetate, n-butanol and aqueous residual fractions of SAF, while F received 2.5 mg/kg b.w. of glibenclamide. In the second phase, forty-nine rats were assigned into seven groups (A-G) of seven rats each. Group A received distilled water. Animals in Groups B-G were also made diabetic by alloxan treatment. B received 0.5 mL of distilled water; C, D, E and F were treated with 5.77, 25.96, 15.40, 27.87 mg/kg b.w (equivalent dose of 75 mg/kg b.w.) of sub-fractions obtained from the ethyl acetate fraction of SAF respectively whereas G received 2.5 mg/kg b.w. of glibenclamide. Fasting blood glucose (FBG), serum lipids, albumin, globulin, liver glycogen, urine ketone, hexokinase and glucose-6-phosphate dehydrogenase activities, α-glucosidase and α-amylase inhibitory activities and cardiac function indices were evaluated using standard methods. Compounds D, E and F isolated from ethyl acetate sub-fraction B were evaluated for in vitro anti-diabetic activity. The structure of the anti-diabetic compound was identified using FTIR, ¹H-NMR, ¹³C-NMR, HCOSY, HSQC and HMBC. Data were subjected to Analysis of Variance and Duncan Multiple Range Test at p < 0.05.

RESULTS

Alloxan treatment increased the levels of FBG, total cholesterol, LDL-cholesterol, VLDL-cholesterol, urine ketone and cardiac function indices and reduced the levels of globulin, albumin, HDL-cholesterol, globulin, liver glycogen, hexokinase and glucose-6-phosphate dehydrogenase activities. Ethyl acetate fraction and sub-fraction B reversed the level and/or activities of these biochemical indices to levels and/or activities that compared favourably with the distilled water treated non-diabetic animals. Of the three compounds (D, E and F) that were obtained from the sub-fraction B, compound E which was Emodin (1, 3, 8-trihydroxy-6-methylanthraquinone) produced the highest α-glucosidase and α-amylase inhibitory activities.

CONCLUSION

Emodin is one of the bioactive constituents present in Senna alata flower.

Prevention of Oxidative Stress-Induced Pancreatic Beta Cell Damage by Broussonetia Kazinoki Siebold Fruit Extract Via the ERK-Nox4 Pathway

Pancreatic beta cells are vulnerable to oxidative stress, which causes beta cell death and dysfunction in diabetes mellitus. Broussonetia kazinoki Siebold (BK) is a widely used herbal medicine, but its potential effects against beta cell death-induced diabetes have not been studied. Therefore, we investigated the protective effect of an ethanolic extract of BK fruit (BKFE) against streptozotocin (STZ)-induced toxicity in pancreatic beta cells. Intraperitoneal injection of STZ in mice induced hyperglycemia; however, oral administration of BKFE significantly decreased the blood glucose level as well as HbA1c levels. BKFE treatment improved glucose tolerance and increased body weight in diabetic mice. Moreover, BKFE treatment resulted in increased serum insulin levels and insulin expression in the pancreas as well as decreased 4-hydroxynonenal levels induced by oxidative stress. Treatment with STZ decreased cell viability of mouse insulinoma cells (MIN6), which was blocked by BKFE pretreatment. BKFE significantly inhibited apoptotic cells and decreased the expression levels of cleaved-caspase-3 and cleaved-poly (ADP-ribose) polymerase (PARP) induced by STZ treatment. Production of reactive oxygen species in STZ-treated MIN6 cells was also significantly decreased by treatment with BKFE. Erk phosphorylation and Nox4 levels increased in STZ-treated MIN6 cells and the pancreas of mice injected with STZ and this increase was inhibited by treatment with BKFE. Inhibition of Erk phosphorylation by treatment with the PD98059 inhibitor or siRNA Erk also blocked the expression of Nox4 induced by STZ treatment. In conclusion, BKFE inhibits Erk phosphorylation, which in turn prevents STZ-induced oxidative stress and beta cell apoptosis. These results suggested that BKFE can be used to prevent or treat beta cell damage in diabetes.

Dimeric glycosylated flavan-3-ol and antimicrobial in vitro evaluation of Trichilia catigua extracts

Trichilia catigua is a tree known as "catuaba", widely distributed in Brazil. Studies carried out with T. catigua barks suggest that plant has antidepressant, antidiabetic, antimicrobial, antioxidant, antiviral, and preventive against brain damage. The aim of this work was to isolate and characterise compounds from the semipurified fraction of T. catigua barks, and to conduct microbiological screening against bacteria and fungi. The crude extract (CE) of "catuaba" was produced by turbo extraction with acetone-water, and later, partitioned to yield ethyl-acetate (EAF) and aqueous (AqF) fractions. From AqF the new catechin-3-O-α-L-rhamnoside-(4α→8)-epicatechin was isolated, identified, and described here for the first time. Regarding antimicrobial activity, the extracts presented impressive results, mainly for Vancomycin Resistant Enterococcus faecium (VREfm) with MIC of 156.5 μg/mL. The results suggest that extract of T. catigua could potentially be used as an adjuvant to treatment and is a promising candidate for the development of new antimicrobial drugs.

Administration of human umbilical cord blood mononuclear cells restores bladder dysfunction in streptozotocin-induced diabetic rats

OBJECTIVE

This study evaluated the effect of human umbilical cord blood mononuclear cells (HUCB-MNCs) on bladder dysfunction in streptozotocin (STZ; 35 mg/kg, i.v.)-induced diabetic rats.

METHODS

Adult male Sprague-Dawley rats (n = 30) were equally divided into three groups: control group, STZ-diabetic group, and HUCB-MNC-treated group (1 × 10⁶ cells). HUCB-MNCs were isolated by density gradient centrifugation from eight healthy donors and injected into the corpus cavenosum in STZ-diabetic rats 4 weeks after the induction of diabetes. Studies were performed 4 weeks after HUCB-MNC or vehicle injection. In vitro organ bath studies were performed on bladder strips, whereas protein expression of hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and α-smooth muscle actin (SMA) in the bladder and the ratio of smooth muscle cells (SMCs) to collagen were determined using western blotting and Masson trichrome staining.

RESULTS

Neurogenic contractions of detrusor smooth muscle strips were 55% smaller in the diabetic group than control group (P < 0.05); these contractions were normalized by HUCB-MNC treatment. In addition, HUCB-MNC treatment restored the impaired maximal carbachol-induced contractile response in detrusor strips in the diabetic group (29%; P < 0.05). HUCB-MNC treatment improved the KCl-induced contractile response in the diabetic bladder (68%; P < 0.05), but had no effect on ATP-induced contractile responses. Increased expression of HIF-1α and VEGF protein and decreased expression of α-SMA protein and the SMC/collagen ratio in diabetic rats were reversed by HUCB-MNC.

CONCLUSION

Administration of HUCB-MNCs facilitates bladder function recovery, which is likely related to downregulation of HIF-1α expression and attenuation of fibrosis in STZ-diabetic rats.

Effects of Cannabidiol on Diabetes Outcomes and Chronic Cerebral Hypoperfusion Comorbidities in Middle-Aged Rats

Diabetes and aging are risk factors for cognitive impairments after chronic cerebral hypoperfusion (CCH). Cannabidiol (CBD) is a phytocannabinoid present in the Cannabis sativa plant. It has beneficial effects on both cerebral ischemic diseases and diabetes. We have recently reported that diabetes interacted synergistically with aging to increase neuroinflammation and memory deficits in rats subjected to CCH. The present study investigated whether CBD would alleviate cognitive decline and affect markers of inflammation and neuroplasticity in the hippocampus in middle-aged diabetic rats submitted to CCH. Diabetes was induced in middle-aged rats (14 months old) by intravenous streptozotocin (SZT) administration. Thirty days later, the diabetic animals were subjected to sham or CCH surgeries and treated with CBD (10 mg/kg, once a day) during 30 days. Diabetes exacerbated cognitive deficits induced by CCH in middle-aged rats. Repeated CBD treatment decreased body weight in both sham- and CCH-operated animals. Cannabidiol improved memory performance and reduced hippocampal levels of inflammation markers (inducible nitric oxide synthase, ionized calcium-binding adapter molecule 1, glial fibrillary acidic protein, and arginase 1). Cannabidiol attenuated the decrease in hippocampal levels of brain-derived neurotrophic factor induced by CCH in diabetic animals, but it did not affect the levels of neuroplasticity markers (growth-associated protein-43 and synaptophysin) in middle-aged diabetic rats. These results suggest that the neuroprotective effects of CBD in middle-aged diabetic rats subjected to CCH are related to a reduction in neuroinflammation. However, they seemed to occur independently of hippocampal neuroplasticity changes.

Aerobic Exercise Training Attenuates Tumor Growth and Reduces Insulin Secretion in Walker 256 Tumor-Bearing Rats

Aerobic exercise training can improve insulin sensitivity in many tissues; however, the relationship among exercise, insulin, and cancer cell growth is unclear. We tested the hypothesis that aerobic exercise training begun during adolescence can attenuate Walker 256 tumor growth in adult rats and alter insulin secretion. Thirty-day-old male Wistar rats engaged in treadmill running for 8 weeks, 3 days/week, 44 min/day, at 55-65% VO2max until they were 90 days old (TC, Trained Control). An equivalently aged group was kept inactive during the same period (SC, Sedentary Control). Then, half the animals of the SC and TC groups were reserved as the control condition and the other half were inoculated with Walker 256 cancer cells, yielding two additional groups (Sedentary Walker and Trained Walker). Zero mortalities were observed in tumor-bearing rats. Body weight (BW), food intake, plasma glucose, insulin levels, and peripheral insulin sensitivity were analyzed before and after tumor cell inoculation. We also evaluated tumor growth, metastasis and cachexia. Isolated pancreatic islets secretory activity was analyzed. In addition, we evaluated mechanic sensibility. Our results showed improved physical performance according to the final workload and VO2max and reduced BW in trained rats at the end of the running protocol. Chronic adaptation to the aerobic exercise training decreased tumor weight, cachexia and metastasis and were associated with low glucose and insulin levels and high insulin sensitivity before and after tumor cell inoculation. Aerobic exercise started at young age also reduced pancreatic islet insulin content and insulin secretion in response to a glucose stimulus, without impairing islet morphology in trained rats. Walker 256 tumor-bearing sedentary rats also presented reduced pancreatic islet insulin content, without changing insulin secretion through isolated pancreatic islets. The mechanical sensitivity test indicated that aerobic exercise training did not cause injury or trigger inflammatory processes prior to tumor cell inoculation. Taken together, the current study suggests that aerobic exercise training applied during adolescence may mitigate tumor growth and related disorders in Walker 256 tumor-bearing adult rats. Improved insulin sensibility, lower glucose and insulin levels and/or reduced insulin secretion stimulated by glucose may be implicated in this tumor attenuation.

Stevia Nonsweetener Fraction Displays an Insulinotropic Effect Involving Neurotransmission in Pancreatic Islets

Stevia rebaudiana (Bert.) Bertoni besides being a source of noncaloric sweeteners is also an important source of bioactive molecules. Many plant extracts, mostly obtained with ethyl acetate solvent, are rich in polyphenol compounds that present insulinotropic effects. To investigate whether the nonsweetener fraction, which is rich in phenolic compounds isolated from Stevia rebaudiana with the solvent ethyl acetate (EAF), has an insulinotropic effect, including interference at the terminals of the autonomic nervous system of the pancreatic islets of rats. Pancreatic islets were isolated from Wistar rats and incubated with EAF and inhibitory or stimulatory substances of insulin secretion, including cholinergic and adrenergic agonists and antagonists. EAF potentiates glucose-stimulated insulin secretion (GSIS) only in the presence of high glucose and calcium-dependent concentrations. EAF increased muscarinic insulinotropic effects in pancreatic islets, interfering with the muscarinic receptor subfamily M3. Adrenergic inhibitory effects on GSIS were attenuated in the presence of EAF, which interfered with the adrenergic α2 receptor. Results suggest that EAF isolated from stevia leaves is a potential therapy for treating type 2 diabetes mellitus by stimulating insulin secretion only in high glucose concentrations, enhancing parasympathetic signal transduction and inhibiting sympathetic signal transduction in beta cells.

Antidiabetic plant-derived nutraceuticals: a critical review

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.