Effect of chromium picolinate on histopathological alterations in STZ and neonatal STZ diabetic rats

Syringic Acid Ameliorates Cardiac, Hepatic, Renal and Neuronal Damage Induced by Chronic Hyperglycaemia in Wistar Rats: A Behavioural, Biochemical and Histological Analysis

This study investigated the effects of syringic acid (SA) on renal, cardiac, hepatic, and neuronal diabetic complications in streptozotocin-induced neonatal (nSTZ) diabetic rats. STZ (110 mg/kg i.p) was injected into Wistar rat neonates as a split dose (second and third postnatal day). Diabetes mellitus was diagnosed in adults by measuring fasting blood glucose levels, urine volume, and food and water intake. The treatment of SA (25 mg/kg, 50 mg/kg p.o) was given from the 8th to 18th postnatal week. To assess the development of diabetic complications and the effect of therapy, biochemical indicators in serum and behavioural parameters were recorded at specific intervals during the study period. SA (25 mg/kg, 50 mg/kg p.o) treatment reduced hyperglycaemia, polydipsia, polyphagia, polyuria, relative organ weight, cardiac hypertrophic indices, inflammatory markers, cell injury markers, glycated haemoglobin, histopathological score, and oxidative stress, and increased Na/K ATPase activity. These findings suggest that SA might significantly alleviate diabetic complications and/or renal, neuronal, cardiac, and hepatic damage in nSTZ diabetic rats.

Bilobalide Enhances AMPK Activity to Improve Liver Injury and Metabolic Disorders in STZ-Induced Diabetes in Immature Rats via Regulating HMGB1/TLR4/NF-κB Signaling Pathway

This study was aimed at examining the effect and underlying mechanisms of bilobalide (BB) on hepatic injury in streptozotocin- (STZ-) induced diabetes mellitus (DM) in immature rats. Immature rats (one day old) were randomly divided into five groups: group I, control nondiabetic rats; group II, STZ-induced, untreated diabetic rats; groups III/IV/V, STZ-induced and BB-treated diabetic rats, which were intraperitoneally injected with BB (2.5 mg/kg, 5 mg/kg, or 10 mg/kg) after 3 days followed by STZ treatment. We observed that BB improved the histopathological changes and maintained normal glucose metabolism, blood lipid, and liver function indicators, such as fasting blood glucose, obesity index, HbA1c, HOMA-IR, fast serum insulin, adiponectin, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), aspartate transaminase (AST), and alanine transaminase (ALT) in STZ-induced DM in immature rats by a biochemical analyzer or ELISA. Meanwhile, Western blot analysis showed that in STZ-induced DM immature rats, BB decreased the expression of apoptosis-related proteins Bax, cleaved caspase-3, and cleaved caspase-9 while enhancing the Bcl-2 expression; BB downregulated the expression of ACC related to fat anabolism, while upregulating the expression of CPT-1 related to fat catabolism. Strikingly, treatment with BB significantly increased the expression of AMPKα1 as well as inhibited HMGB1, TLR4, and p-P65 expression in hepatic tissues of immature DM rats. AMPK inhibitor (compound C, CC) cotreated with BB undermined the protective effect of BB on the liver injury. The results of the present study suggested BB may have a significant role in alleviating liver damage in the STZ-induced immature DM rats.

Synthetic Zeolite Supplementation as a Potential Candidate for the Therapy of Diabetic Syndrome

<b>Background and Objective:</b> Natural and Synthetic Zeolite (SZ) is potentially useful for biopharmaceuticals and bio tools due to its unique and outstanding physical and chemical properties. Thus, the present study aimed to evaluate the possible effect of synthetic zeolite in (STZ)-induced diabetic rats. <b>Materials and Methods:</b> About 4 groups of rats were used, (I) normal control, (II) SZ group, (300 mg/kg/day), (III) STZ group, diabetic rats acted as positive control and (IV) STZ+SZ group, included diabetic rats treated with synthetic zeolite (300 mg/kg/day), statistical analysis comparisons between means were carried out using one-way analysis of variance (ANOVA) followed by a post hock (Tukey) multiple comparisons test at p<u>></u>0.05. <b>Results:</b> After six weeks, treatment of diabetic animals with synthetic zeolite markedly exhibited a significant reduction in glucose, lipids, DNA fragmentation, Alanine Aminotransferase (ALAT), Aspartate Aminotransferase (ASAT), urea, creatinine, Malondialdehyde (MDA) and Nitric Oxide (NO) levels concomitant with a significant rise in insulin, Glutathione (GSH), Superoxide Dismutase (SOD) and Catalase (CAT) values close to the corresponding values of healthy ones. <b>Conclusion:</b> In conclusion, synthetic zeolite exhibits multi-health benefits with promising potentials against STZ-induced diabetes, this behaviour may be attributed to its antioxidant and free radical scavenging mechanisms.

Protective Effects of Chromium Picolinate Against Diabetic-Induced Renal Dysfunction and Renal Fibrosis in Streptozotocin-Induced Diabetic Rats

Diabetic nephropathy (DN) is one of the most important complications of diabetes, and the leading cause of end-stage renal disease (ESRD). While Chromium picolinate (CrPic) supplementation has been found to be effective in treating diabetes, its effects on diabetic-induced nephropathy have not been studied. Therefore, in this study, CrPic (1 mg kg⁻¹ d⁻¹) was administered to a DN rat model by oral gavage for eight weeks to investigate its effects. The results show that CrPic supplementation caused a decrease in levels of blood glucose, serum insulin, blood urea nitrogen (BUN), serum creatinine, and urinary albumin in DN rats. It also reversed renal pathological changes, including renal glomerular sclerosis and interstitial fibrosis. In addition, the oxidative defense system in the kidneys of DN rats was found to be improved; the biological activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) increased; and the content of malondialdehyde (MDA) lowered. Immunohistochemical results reveal that the expression levels of renal transforming growth factor-β1 (TGF-β1), Smad 2, and Smad 3 decreased significantly in the kidneys of rats in the CrPic-treated group. CrPic administration was thus found to ameliorate diabetic nephropathy in SD rats via an antioxidative stress mechanism, as well the ability to inhibit TGF-β1/Smad2/3 expression. This study suggests that CrPic could be a potential renal-protective nutrient against diabetic nephropathy.

Streptozotocin-Induced Diabetes Mellitus in Neonatal Rats: An Insight into its Applications to Induce Diabetic Complications

BACKGROUND

Diabetic complications are the major contributor in the mortality of diabetic patients despite controlling blood glucose level. In the journey of new drug discovery, animal models have to play a major role. A large number of chemical-induced and genetically modified animal models have been investigated to induce diabetic complications but none of them was found to be mimicking the pathophysiology of the human. Therefore, the search and identification of the appropriate animal model become essential.

OBJECTIVE

In the present review, we have made an attempt to understand the pathophysiology of diabetic complication in the neonatal streptozotocin-diabetic rat model and tried to identify the targets for therapeutic agents. The review will help the researchers to explore the animal model to induce diabetic complications, to identify targets and further to find lead molecules for treatment or prevention of diabetic complications.

METHODS

We have compiled the available research work from 1974 by using prominent databases, organized the available information and analyzed the data to improve the understanding of the pathophysiology of streptozotocin-induced diabetic complications in neonates of rats.

RESULTS

The neonatal streptozotocin-diabetic rat model is frequently used and well-established animal model for type 2 diabetes mellitus. We have found that this model has been used to study the pathogenesis of various micro and macrovascular diabetic complications and also investigated for its effects on the liver, thymus gland, and brain. The underlying pathophysiology for complications had a resemblance to the human.

CONCLUSION

The neonatal streptozotocin-diabetic rat model may demonstrate symptomatic diabetic complications due to persistent hyperglycemia at the age of approximately 18-24 weeks. Critical interpretations of available research work showed that the researcher can explore split dose STZ (90- 100mg/kg b.w) model to induce Type 2 DM in neonates of rats at 2nd or 3rd postnatal day.

Chronic saponin treatment attenuates damage to the pancreas in chronic alcohol-treated diabetic rats

Background

Chronic heavy alcohol consumption may raise the risk of developing type 2 diabetes mellitus. Saponins inhibit apoptosis of pancreatic islet cells and reduce lipid parameters. The present study was designed to investigate the effect of saponin on chronic ethanol-treated diabetic rats.

Methods

Long–Evans Tokushima Fatty (LETO) and Otsuka Long–Evans Tokushima Fatty (OLETF) rats were pair-fed a Lieber–DeCarli diet with and without 5% ethanol for 12 wks. Two weeks after starting the pair-feeding with the Lieber–DeCarli diet, intraperitoneal injection of saponin was performed for 10 wks. To perform the experiments, rats were divided as follows: LETO-Control (LC), LETO-Ethanol (LE), LETO-Ethanol-Saponin (LES), OLETF-Control (OC), OLETF-Ethanol (OE), and OLETF-Ethanol-Saponin (OES).

Results

The weights of epididymal and mesenteric fat tissue in LES and OES rats were the lightest from among the LETO and OLETF groups, respectively. The secretion of alanine aminotransferase and cholesterol in OES rats decreased significantly compared to their secretion in OC and OE rats, respectively. The islets of the pancreas in LE and OE rats showed clean, unclear, and smaller morphology compared to those of LC, LES, OC, and OES rats. In addition, the expression of insulin in the islets of the pancreas in LC, LES, OC, and OES rats was higher than in LE and OE rats.

Conclusion

Saponin may not only be helpful in alleviating the rapid progress of diabetes due to chronic alcohol consumption in diabetic patients, but may also show potential as an antidiabetic drug candidate for diabetic patients who chronically consume alcohol.

Quercetin Modulates the Effects of Chromium Exposure on Learning, Memory and Antioxidant Enzyme Activity in F1 Generation Mice

In the present study, we investigated whether chromium (Cr) administered to the dams (F0) during lactation period could affect memory and oxidative stress in F1 generation mice in their adulthood and whether quercetin could modulate these effects. Morris water maze (MWM) was used to test for spatial memory. Passive avoidance task and elevated plus maze were used to test for acquisition and retention memory. Oxidative stress was evaluated by measuring glutathione-S-transferase (GST), catalase activity and malonaldehyde (MDA) levels in the brain tissue. The results of MWM showed that the animals in the Cr-treated group compared to control have better spatial memory that was further enhanced when Cr was administered along with quercetin (50 mg/kg). The elevated plus maze test also showed the Cr-treated group to improve acquisition as well as retention memory compared to control. Co-treatment with quercetin (all doses) also exhibited enhanced acquisition and retention memory compared to control. The passive avoidance task demonstrated no significant improvement in memory in the Cr-treated mice but co-treatment with quercetin (100 mg/kg) showed improved acquisition memory compared to control which was significantly better than the animals treated with chromium alone. GST activity was significantly increased in the Cr-treated animals, and this was further increased in groups treated with Cr and quercetin (all doses). Chromium when administered alone and in combination with quercetin (all doses) significantly reduced MDA levels. However, Cr treatment did not show significant change in catalase activity. Nevertheless, co-treatment with quercetin (25 and 50 mg/kg) resulted in significant decrease in catalase activity. Thus, our study demonstrates that Cr exposure during lactation could be beneficial for pups with respect to augmentation of cognitive function and reduction of oxidative stress. Quercetin could probably enhance this effect to some extent.

The Potential of Cr3 [Triaqua-μ3 -Oxo-Hexa-μ-Propionatotrichromium(III) Chloride] to Reduce Birth Defects in the Offspring of Diabetic CD-1 Mice

Diabetes mellitus is a growing concern worldwide and leads to multiple complications during pregnancy. Pharmacologic doses of chromium (Cr) have been linked with improving insulin sensitivity and other positive benefits in the treatment of diabetes in animal models. By using streptozotocin induced hyperglycemia in female CD-1 mice, reproductive outcomes of diabetic and chromium-dosed diabetic females were examined. After dosing 10 mg/kg Cr in the form of triaqua-μ3 -oxo-hexa-μ-propionatotrichromium(III) chloride or Cr3 during gestation days 8-16 (GD8-GD16), all females were sacrificed on gestation day 17 (GD17) and examined for maternal weight gain. The fetuses were examined for gross malformations and for skeletal malformations. The offspring of Cr3-dosed females tended to have a reduction in the incidence of supernumerary ribs. While hyperglycemia still had negative impacts on the health of dams and their offspring, administration of Cr led to an apparent trend in the reduction in the number of malformations and incidence of supernumerary ribs compared to those of untreated diabetic mothers.

Anti-diabetic potential of chromium histidinate in diabetic retinopathy rats

BACKGROUND

Chromium (Cr) is commonly used as a complementary medicine for diabetes mellitus. Several studies suggest that Cr intakes may improve glucose metabolism and decrease oxidative stress. Therefore, we aimed to assess the effects of chromium histidinate (CrHis) supplementation using a range of reliable biomarkers of oxidative damage and histopathological changes in rats with diabetic retinopathy.

METHODS

Diabetes was induced with streptozotocin [(STZ), 55 mg/kg] by intraperitoneal injection in male Long-Evans rats. Three weeks after STZ injection, rats were divided into four groups, namely, untreated normal controls, normal rats receiving CrHis (110 μg/kg/day); untreated diabetics and diabetics treated with CrHis (110 μg/kg/day) orally for 12 weeks.

RESULTS

In the untreated diabetic group, levels of serum glucose, glycosylated haemoglobin (HbA1c), total cholesterol (TC) and retina malondialdehyde (MDA) were significantly increased, while expressions of retina insulin, and glucose transporter 1 (GLUT 1) and glucose transporter 3 (GLUT3) and level of serum insulin were decreased. CrHis supplementation was found to reduce the levels of glucose, HbA1c, total cholesterol and MDA and to improve the GLUT1, GLUT3 and insulin expressions in STZ-induced diabetic rats. CrHis prevents the changes in the expressions of GLUT1, GLUT3 and insulin and the level of MDA in the retina tissue, confirming the protective effect of CrHis supplementation against the retinopathy caused by STZ. Histopathologic findings suggest that the CrHis-treated diabetic group had normal retinal tissue appearance compared with the untreated diabetic group.

CONCLUSIONS

These results verify that CrHis has critical beneficial effects against retinal complications. Although detailed studies are required for the evaluation of the exact mechanism of the ameliorative effects of CrHis against diabetic complications, these preliminary experimental findings demonstrate that CrHis exhibits antidiabetic effects in a rat model of diabetic retinopathy by regulating the glucose metabolism and suppressing retinal tissue damage.

Anti-diabetic effects of ethanol extract of Bryonia laciniosa seeds and its saponins rich fraction in neonatally streptozotocin-induced diabetic rats

Context:

Bryonia laciniosa Linn. (Cucurbitaceae) seed is used in traditional medicine for a number of ailments including metabolic disorders.

Aim:

This study evaluated the anti-diabetic action of the ethanol extract of B. laciniosa seeds and saponin fraction of it through its effect on hyperglycemia, dyslipidaemia and oxidative stress in neonatally streptozotocin (n-STZ)-induced diabetic rats (n-STZ diabetic rats).

Materials and Methods:

Ethanol extract (250 and 500 mg/kg; p.o.), saponin fraction (100 and 200 mg/kg; p.o.) and standard drug glibenclamide (3 mg/kg; p.o.) were administered to diabetic rats when the rats were 6 weeks old and continued for 10 consecutive weeks. Effects of ethanol extract and saponin fraction on various biochemical parameters were studied in diabetic rats.

Results:

The treatment with ethanol extract and saponin fraction for 10 weeks decrease in the levels of glucose, triglycerides, cholesterol, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, serum urea, serum creatinine and diminished activities of aspartate transaminase, and alanine transaminase. The anti-hyperglycemic nature of B. laciniosa is probably brought about by the extra- the pancreatic mechanism as evidenced from unchanged levels of plasma insulin. B. laciniosa modulated effect of diabetes on the liver malondialdehyde, reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity. Administration of ethanol extract and saponin fraction to diabetic rats showed a significant reversal of disturbed antioxidant status. Significant increase in SOD, CAT, and levels of GSH was observed in treated n-STZ diabetic rats.

Conclusion:

The present study reveals the efficacy of B. laciniosa seed extract and its saponin fraction in the amelioration of n-STZ diabetic rats.

The effect of Angipars on diabetic neuropathy in STZ-induced diabetic male rats: a study on behavioral, electrophysiological, sciatic histological and ultrastructural indices

Diabetes mellitus is the most common metabolic disease with a high prevalence rate in human society that eventually leads to the peripheral nervous system complications in a great number of patients. In the present study, the effects of Angipars on nerve conduction velocity, histological alterations, and behavioral indices were investigated. Diabetes was induced in male rats by intraperitoneal injection of streptozotocin (STZ). Six weeks after STZ injection, animals were divided into five groups control, vehicle, and 3 experimental groups. The vehicle group received 1 mL distilled water daily for two weeks and three experimental groups received, respectively, intraperitoneal injection of 5, 10, and 20 mg/kg Angipars daily for two weeks. Intraperitoneal injection of Angipars, in some extent, could significantly improve behavioral indices of the experimental groups as compared to the vehicle group. Furthermore, mean nerve conduction velocity in the vehicle group showed significant difference with that in the control and the 2nd experimental groups; therefore, Angipars could increase nerve conduction velocity in neuropathic rats. Overall, Angipars exerted positive effects on the treatment and reduction of physiologic symptoms and improvement of sciatic morphological injuries in neuropathic rats.

Evaluation of neonatal streptozotocin induced diabetic rat model for the development of cataract

Type 2 diabetes (T2D) generally follows prediabetes (PD) conditions such as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT). Although studies reported an association of IGT or IFG with cataract, the experimental basis for PD associated cataract is not known. Hence, we evaluated neonatal streptozotocin (nSTZ) induced rat model to study PD associated cataractogenesis by injecting STZ to two-day old rats. While majority (70%) of nSTZ injected pups developed IGT (nSTZ-PD) by two months but not cataract even after seven months, remaining (30%) nSTZ rats developed hyperglycemia (nSTZ-D) by two months and mature cataract by seven months. Lens biochemical analysis indicated increased oxidative stress as indicated by increased SOD activity, lipid peroxidation, and protein carbonyl levels in nSTZ-D cataractous lens. There was also increased polyol pathway as assessed by aldose reductase activity and sorbitol levels. Though nSTZ-PD animals have not shown any signs of lenticular opacity, insolubilization of proteins along with enhanced polyol pathway was observed in the lens. Further there was increased oxidative stress in lens of IGT animals. These results suggest that oxidative stress along with increased polyol pathway might play a role in IGT-associated lens abnormalities. In conclusion, nSTZ-PD rat model could aid to investigate IGT-associated lens abnormalities.

Is chromium pharmacologically relevant?

Recent research, combined with reanalysis of previous results, has revealed that chromium can no longer be considered an essential trace element. Clinical studies are ambiguous at best as to whether Cr has a pharmacological effect in humans. Observed effects of Cr on rodent models of insulin resistance and diabetes are best interpreted in terms of a pharmacological role for Cr. Studies on the effects of Cr on rat models of diabetes are reviewed herein and suggest Cr increases insulin sensitivity in peripheral tissues of the rodent models. The lack of effects in human studies may stem from humans receiving a comparably smaller dose than the rodent models. However, given the different responses to Cr in the rodent models, humans could potentially have different responses to Cr.

Effects of Dietary Supplementation with Agaricus sylvaticus Schaeffer on Glycemia and Cholesterol after Streptozotocin-Induced Diabetes in Rats

This study evaluated the effect of the Agaricus sylvaticus (sun mushroom) on biochemical tests of the plasma and on the morphology of the pancreas in an experimental model of type I diabetes mellitus (DM1) induced by streptozotocin. One gram of dry A. sylvaticus was homogenized and mixed with the chow. Male Wistar rats were allocated as follows: normoglycemic control that received commercial chow; normoglycemic control group that received chow with A. sylvaticus; diabetic group that received commercial chow; and diabetic group that received chow with A. sylvaticus. Weight, food, and water consumption were measured every two days. Blood glucose levels were measured twice a week. After 30 days, the animals were euthanized and blood was collected for the analysis of cholesterol, HDL, triglycerides, blood sugar, glutamic-pyruvic transaminase (GPT), alkaline phosphatase, iron, transferrin, and urea. The pancreas was processed for microscopic analysis. A. sylvaticus modulated the levels of cholesterol, HDL, triglycerides, blood sugar, GPT, alkaline phosphatase, iron, transferrin, and urea to levels similar to those found in the controls and led to compensatory hyperplasia of the islets of Langerhans. A. sylvaticus is potentially beneficial in the control of type 1 diabetes, and it may also prevent pancreas damage.

Repeated oral administration of Febi super bitters correlated with some tissue toxicity in male Wistar rat

This study investigated the toxic implication of Febi Super Bitters in Male Wistar rats because of upsurge in its usage for therapeutic reasons. Eighteen rats, with an average weight of 86.2 +/- 4.43 g, were randomly distributed into three equal groups of six rats per group. The rats were acclimatized for 14 days and 0.308 and 0.462 mL kg(-1) b.wt. of Febi super bitters were administered daily to groups B and C, respectively for 56 days, while group A received distilled water. The toxicity of the herbal bitter was assessed by determining the activities of Lactate Dehydrogenate (LDH), Alkaline Phosphatase (ALP) and Acid Phosphatase (ACP) in the liver, kidney, small intestine, heart, brain, lungs, spleen, serum and histological studies on the organs. The activities of LDH were significantly reduced (p < 0.05) in the liver, small intestine and lung, while it increased significantly (p < 0.05) in the brain and serum. ALP activities decreased significantly (p < 0.05) in the liver, kidney, small intestine and heart but increased (p < 0.05) in brain, spleen and serum. ACP activities in the liver and kidney were decreased (p<0.05) and increased significantly (p < 0.05) in the spleen and serum. Increases were significantly recorded in serum total bilirubin, unconjugated bilirubin, total protein and globulin, while reductions were recorded in the conjugated bilirubin and A/G (p < 0.05). Histoarchitecture of the lungs, spleen and small intestine revealed marked cellular distortions. In the light of these findings, the habitual consumption of Febi super bitters is not recommended as it has underlined toxicity in some vital internal organs.

Platycodi radix saponin inhibits α-glucosidase in vitro and modulates hepatic glucose-regulating enzyme activities in C57BL/KsJ-db/db mice

This study investigated anti-diabetic activity of a concentrated saponin fraction from Platycodi radix (SK1) in C57BL/KsJ-db/db mice and its underlying mechanism. Mice were fed diet with 0.5 % SK1 (w/w) for 6 weeks. SK1 significantly lowered the blood glucose and glycosylated hemoglobin levels and improved glucose and insulin tolerance. The plasma and pancreatic insulin and C-peptide levels and fecal cholesterol content were increased, whereas plasma urea nitrogen, free fatty acid and triglyceride levels were decreased by SK1 supplementation. Glucokinase (GK) activity in the liver was significantly higher in the SK1 group than the control group, whereas the glucose-6-phosphatase (G6Pase) activity was lower. SK1 significantly down-regulated GK mRNA expression compared to the control group but did not affect G6Pase and glucose transporter 2 mRNA. Phosphoenolpyruvate carboxykinase activity and mRNA levels did not differ between groups. SK1 also markedly inhibited the small intestinal disaccharidases activities compared to those of control db/db mice. Furthermore, SK1 was a more effective α-glucosidase inhibitor than acarbose in vitro. Overall, these findings suggest that SK1 is a potential glucose-lowering agent that functions via inhibition of carbohydrate digestive enzyme activities and modulation of glucose-regulating enzyme activities in db/db mice.

Antihyperglycemic and antihyperlipidemic activities of 2-(4-[(2-hydroxybenzyl) amino]-phenyl amino-methyl)-phenol in STZ induced diabetic rats

Oral administration of 2-(4-[(2-hydroxybenzyl) amino]-phenyl amino-methyl)-phenol (HBPMP) (30 mg/kg) to Streptozotocin (STZ) rats produced significant antidiabetic activity after 6 h of HBPMP administration. Treatment of the STZ rats with HBPMP (30 mg/kg/day) for 30 days resulted in a significant decrease in their Fasting Blood Glucose (FBG), Serum Total Cholesterol (TC), Low Density Lipoprotein-Cholesterol (LDL-C), Very Low Density Lipoprotein-Cholesterol (VLDL-C) and triglycerides (TG) along with an increase in serum High Density Lipoprotein-Cholesterol (HDL-C) levels. Activities of Serum Aspartate transaminase (AST), Alanine transaminase (ALT) and Alkaline phosphatase (ALP) and levels of blood urea and creatinine were improved to near normal levels in the treated STZ rats indicating the protective role of the HBPMP against liver and kidney damage and its non-toxic property. In conclusion, HBPMP possesses antihyperglycemic and antihyperlipidemic activities.

Sustained delivery of IL-1Ra from PF127-gel reduces hyperglycemia in diabetic GK-rats

Interleukin-1beta (IL-1β) is a major cause for induction of various inflammatory mechanisms that are decisively involved to provoke pathogenesis of type 2 diabetes mellitus (T2DM). Interleukin-1 receptor antagonist (IL-1Ra) a naturally occurring anti-inflammatory antagonist of IL-1β has been recently approved for treatment of T2DM but due to its short half-life, higher doses and frequent dosing intervals are required. Pluronic F-127 (PF127) has previously shown to prolong the release of various proteinous drugs and their serum half-lives. Subsequently, in our previous work, we developed a new dosage form of IL-1Ra using PF127 and investigated its in-vitro and in-vivo effects. Here in present work, we have extended this approach using diabetic Goto-kakizaki (GK) rats. We administered IL-1Ra loaded in PF127 gel subcutaneously for one month into GK rats. IL-1Ra loaded in PF127 gel exhibited a sustained and prolonged hypoglycemic effects on treated animals. Intraperitoneal glucose tolerance test (IPGTT) results showed that IL-1Ra loaded in PF127 gel increased glucose tolerance along with increased insulin sensitivity and β-cell’s secretory function in treated rats. Moreover, significant reduction in pro-insulin/insulin ratio, lipid profiles and interleukin 6 (IL-6) were also observed. Immunohistochemical analysis showed slight macrophages infiltration in pancreatic islets. Histochemical analysis revealed no PF127-induced alteration in the normal physiology of skin and kidney of treated animals. Hence, we concluded that IL-1Ra loaded in PF127 gel has potential to exhibit broad spectrum anti-inflammatory effects alleviating the symptoms of T2DM.

Chromium: is it essential, pharmacologically relevant, or toxic?

Over fifty years ago, the element chromium (as the trivalent ion) was proposed to be an essential element for mammals with a role in maintaining proper carbohydrate and lipid metabolism. Evidence for an essential role came from dietary studies with rodents, studies on the effects of chromium on subjects on total parenteral nutrition, and studies of the absorption and transport of chromium. Over the next several decades, chromium-containing nutritional supplements became so popular for weight loss and muscle development that sales were second only to calcium among mineral supplements. However, the failure to identify the responsible biomolecules(s) that bind chromium(III) and their mode of action, particularly a postulated species named glucose tolerance factor or GTF, resulted in the status of chromium being questioned in recent years, such that the question of its being essential needs to be formally readdressed. At the same time as chromium(III)'s popularity as a nutritional supplement was growing, concerns over its safety appeared. While chromium has been conclusively shown not to have beneficial effects on body mass or composition and should be removed from the list of essential trace elements, chromium(III) compounds are generally nontoxic and have beneficial pharmacological effects in rodents models of insulin insensitivity, although human studies have not conclusively shown any beneficial effects. Mechanisms have been proposed for these pharmacological effects, but all suffer from a lack of consistent supporting evidence.

Chromium picolinate and chromium histidinate protects against renal dysfunction by modulation of NF-κB pathway in high-fat diet fed and Streptozotocin-induced diabetic rats

Background

Diabetic nephropathy is one of major complications of diabetes mellitus. Although chromium is an essential element for carbohydrate and lipid metabolism, its effects on diabetic nephropathy are not well understood. The present study was conducted to investigate the effects of chromium picolinate (CrPic) and chromium histidinate (CrHis) on nuclear factor-kappa B (NF-κB) and nuclear factor-E2-related factor-2 (Nrf2) pathway in the rat kidney.

Methods

Male Wistar rats were divided into six groups. Group I received a standard diet (8% fat) and served as a control; Group II was fed with a standard diet and received CrPic; Group III was fed with a standard diet and received CrHis; Group IV received a high fat diet (HFD, 40% fat) for 2 weeks and then were injected with streptozotocin (STZ) (HFD/STZ); Group V was treated as group IV (HFD/STZ) but supplemented with CrPic for 12 weeks. Group VI was treated as group IV (HFD/STZ) but supplemented with CrHis.

Results

The increased NF-κβ p65 in the HFD/STZ group was inhibited by CrPic and CrHis supplementation (P < 0.05). In STZ-treated rats, a significant decrease in levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) was found in kidney tissues when compared to control rats (P < 0.05). A significant increase in the levels of IκBα was observed in CrPic- and CrHis-treated rats when compared with STZ-treated rats. Renal Nrf2 levels were significantly decreased in diabetic rats compared with the control rats. There was a higher tendency for increase of kidney Nrf2 level and decrease in kidney NFκBp65 levels and 4- hydroxyl nonenal (4-HNE) protein adducts (P < 0.05) in diabetic rats.

Conclusion

Our result show that in kidney tissue CrHis/CrPic increases Nrf2 level, parallelly decreases NF-κB and partially restores IκBα levels in HFD/STZ group, suggesting that CrPic and CrHis may play a role in antioxidant defense system via the Nrf2 pathway by reducing inflammation through NF-κβ p65 inhibition. Moreover, a greater reduction in NF-κB expression and greater increases in expressions of IκBα and Nrf2 in diabetic rats supplemented with CrHis than rats supplemented with CrPic suggest that CrHis has more favorable effects than CrPic.

Experimentally induced rodent models of type 2 diabetes

Diabetes is one of the major global public health problems and is gradually getting worse particularly in developing nations where 95% of patients are suffering from type 2 diabetes (T2D). Animal models in diabetes research are very common where rodents are the best choice of use due to being smaller in size, easy to handle, omnivorous in nature, and non-wild tranquil behavior. Normally rodent models are classified into two major classes namely: (1) genetic or spontaneously induced models and (2) non-genetic or experimentally induced models. Non-genetic models are more popular compared to genetic models due to lower cost, wider availability, easier to induce diabetes, and of course easier to maintain compared to genetic models. A number of non-genetic models have been developed in last three decades for diabetes research including adult alloxan/streptozotocin (STZ) models, partial pancreatectomy model, high-fat (HF) diet-fed models, fructose-fed models, HF diet-fed STZ models, nicotinamide-STZ models, monosodium-glutamate (MSG) induced models, and intrauterine growth retardation (IUGR) models. A T2D model should have the all major pathogenesis of the disease usually found in humans; however, none of the above-mentioned models are without limitations. This chapter comparatively evaluates most of the experimentally induced rodent models of T2D with their limitations, advantages, disadvantages, and criticality of development in order to help diabetes research groups to more appropriately select the animal models to work on their specific research question.

Ameliorating effect of chromium administration on hepatic glucose metabolism in streptozotocin-induced experimental diabetes

Chromium has been recognized as an essential trace element that plays an important role in carbohydrate metabolism. However, the molecular mechanisms involved in its action are not clear. This study was undertaken to understand the mechanism of chromium action in experimental diabetes. Streptozotocin-induced diabetic animals were administered chromium as chromium picolinate (CrP) at a daily dose of 1 mg/kg body weight for a period of 4 weeks. It was observed that chromium complexed with picolinate was effective in lowering plasma glucose levels as well as was able to alleviate polyphagia, polydipsia, and weight loss in diabetic animals. Administration of chromium was also found to normalize glycogen content in liver of diabetic animals to near control levels. The reduction in plasma glucose levels by chromium was accompanied by increase in activity of glycolytic enzymes (e.g., glucokinase, phosphofructokinase, and pyruvate kinase) and by suppression in activity of gluconeogenic enzymes (e.g., glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) in liver. Hepatic glucose uptake was found to be increased by chromium supplementation as demonstrated by decrease in Km and increase in Vmax values in diabetic animals. Chromium levels were lower in the liver of diabetic rats when compared with that of control rats. A negative correlation was observed between plasma glucose and chromium concentration in patients with diabetes. The data suggests that chromium supplementation as CrP is beneficial in correcting hyperglycemia, implying that the modulation of the glucose metabolism by chromium may be therapeutically beneficial in the treatment of diabetes.

Evaluation of anti-diabetic potential of chromium(III) propionate complex in high-fat diet fed and STZ injected rats

The aim of this study was to examine the anti-diabetic potential of the chromium(III) propionate complex (CrProp) in a diabetic rat model. Male Wistar rats (n=28, 8-week old) were divided into 4 groups (with 7 rats each) and fed at libitum: the control diet (AIN-93M), and high-fat diets with or without supplementary CrProp (10 and 50mg Crkg(-1) diet; 1 and 5 mg kg(-1) body mass per day) for 5 weeks, and subsequently injected with STZ to induce diabetes. Rats were further fed the same diets for another week until the end of the experiment. Blood indices and the contents of minerals (Fe, Zn, Cu and Cr) in rat tissues were determined by atomic absorption spectrometry. Supplementary CrProp did not affect blood glucose level, but significantly improved insulin sensitivity (HOMA-IR index) and reduced serum levels of triacylglycerols, total and LDL cholesterols. Both supplementary dosages of CrProp (10 and 50mg Cr kg(-1) diet) normalized the increased liver Fe content, reduced hepatic and renal Cu levels and elevated renal Cr contents in diabetic rats. In conclusion, CrProp has a significant anti-diabetic (insulin-sensitizing and hypolipidemic) potential; thus it might be a candidate for a therapeutic agent in diabetes.

Effect of chromium supplementation on the diabetes induced-oxidative stress in liver and brain of adult rats

This study was designed to investigate the susceptibility of liver and brain tissues, as insulinin-dependent tissues, of normal adult male rats to the oxidative challenge of subchronic supplementation with chromium picolinate (CrPic) at low (human equivalent) and high doses (2.90 and 13.20 μg Cr kg(-1) day(-1), respectively). Also, the modulative effect of CrPic administration on the enhanced oxidative stress in the liver and brain tissues of alloxan-diabetic rats was studied. Fasting serum glucose level was not modified in normal rats but significantly reduced in diabetic rats that had received CrPic supplement. A mild oxidative stress was observed in the liver and brain of CrPic-supplemented normal rats confirmed by the dose-dependent reductions in the levels of hepatic and cerebral free fatty acids, superoxide dismutase and glutathione peroxidase activities, and in contrast increased tissue malondialdehyde concentration. On the other hand, hepatic and cerebral catalase activity was reduced in the high dose group only. CrPic supplementation did not act as a peroxisome proliferator confirmed by the significant reductions in liver and brain peroxisomal palmitoyl CoA oxidase activity. The non significant alterations in liver protein/DNA and RNA/DNA ratios indicate that CrPic did not affect protein synthesis per cell, and that mild elevations in hepatic total protein and RNA concentrations might be due to block or decrease in the export rate of synthesized proteins from the liver to the plasma. In diabetic rats, elevated levels of hepatic and cerebral free fatty acids and malondialdehyde, and in contrast the overwhelmed antioxidant enzymes, were significantly modulated in the low dose group and near-normalized in the high dose group. The significant increases observed in liver total protein and RNA concentrations, as well as protein/DNA and RNA/ DNA ratios in diabetic rats supplemented with the high dose of Cr, compared to untreated diabetics, may be related to the improvement in the glycemic status of the diabetic animals rather than the direct effect of CrPic on protein anabolism.

Eicosapentaenoic acid restores diabetic tubular injury through regulating oxidative stress and mitochondrial apoptosis

The present study was designed to elucidate a possible mechanism of hyperglycemia-induced tubular injury and to examine a therapeutic potential of dietary eicosapentaenoic acid (EPA) for the prevention of diabetic kidney disease. Utilizing streptozotocin-induced diabetic mice, the extents of albuminuria and histological injuries were monitored at 2 wk after diabetic induction. Reactive oxygen species (ROS) production, apoptosis, and hypoxia in the kidney were evaluated by immunohistochemistry and Western blotting. An in vitro study was performed using rat proximal tubular cells (NRK-52E) to confirm the protective effect of EPA for methylglyoxal (MG)-induced ROS generation and staurosporine (STS)-induced mitochondrial apoptosis. The extents of albuminuria and histological tubular injuries were significantly lower in EPA-treated diabetic mice compared with untreated diabetic mice. The levels of lipid peroxidation product (4-hydroxy-2-nonenal), oxidative DNA damage (8-hydoxy-deoxyguanosine), and mitochondrial apoptosis (TUNEL, caspase-9, cleaved caspase-3, and cytochrome c release) in the tubular cells were also significantly lower in EPA-treated diabetic mice. Furthermore, hypoxia-inducible factor (HIF)-1α expression was significantly upregulated in the kidney tissues from EPA-treated mice compared with untreated diabetic mice. MG-induced ROS overproduction and STS-induced mitochondrial apoptosis in NRK-52E cells were significantly reduced by EPA treatment in vitro. These results indicated that the ROS generation and mitochondrial apoptosis were involved in hyperglycemia-induced tubular injury and EPA had a beneficial effect by suppressing ROS generation and mitochondrial apoptosis partly through augmentation of an HIF-1α response in diabetic kidney disease.

Chromium(III) propionate complex supplementation improves carbohydrate metabolism in insulin-resistance rat model

The purpose of this study was to evaluate the antidiabetic potential and safety of the chromium(III) propionate complex (CrProp) in insulin resistance induced by a high-fructose diet in rats. The experiment was carried out on 32 nine-week old male Wistar rats divided into 4 groups of 8 rats each. Animals were fed at libitum: the control diet (AIN-93M), and high-fructose diets (HF) containing various levels of Cr(III) given as CrProp (1 mg Cr kg(-1) diet (HF) and supplemented with 10 mg Cr kg(-1) diet (HFCr10), or 50 mg Cr kg(-1) diet (HFCr50), equal to approx. 0.1, 1 and 5 mg kg(-1) body mass per day) for 8 weeks. It was found that supplemental CrProp improved carbohydrate metabolism indices (decreasing serum insulin levels and insulin resistance indices HOMA-IR and HOMA-B, while increasing insulin sensitivity index QUICKI). Supplemental CrProp did not affect overall nutritional indices, blood morphology, most of the toxicity indices, blood glucose and lipids levels, while it increased kidney Cr level (HFCr50), normalized decreased liver Cu concentrations, and decreased kidney Fe and Cu levels (HFCr50). Supplemental CrProp administered at 10- and 50-fold doses of the basal dietary Cr level has a significant antidiabetic effect in insulin resistant rats. However, a prolonged treatment with this compound can affect Fe status.

Effects of chromium histidinate on renal function, oxidative stress, and heat-shock proteins in fat-fed and streptozotocin-treated rats

OBJECTIVE

Chromium is an essential element for carbohydrate, fat, and protein metabolism. The therapeutic potential of chromium histidinate (CrHis) in the treatment of diabetes has been elucidated. The present study investigated the effects of CrHis on serum parameters of renal function, on oxidative stress markers (malondialdehyde [MDA] and 8-isoprostane), and on the expression of heat-shock proteins (HSPs) in rats.

METHODS

Male Wistar rats (n=60, 8 weeks old) were divided into four groups. Group 1 received a standard diet (12% of calories as fat). Group 2 received a standard diet, plus CrHis. Group 3 received a high-fat diet (40% of calories as fat) for 2 weeks, and was then injected with streptozotocin (STZ) on day 14 (STZ, 40 mg/kg intraperitoneally). Group 4 was treated in the same way as group 3 (HFD/STZ), but was supplemented with 110 microg CrHis/kg/body weight/day. Oxidative stress in the kidneys of diabetic rats was evidenced by an elevation in levels of MDA and 8-isoprostane. Protein concentrations of HSP60 and HSP70 in renal tissue were determined by Western blot analyses.

RESULTS

Chromium histidinate supplementation lowered kidney concentrations of MDA, 8-isoprostane levels, serum urea-N, and creatinine, and reduced the severity of renal damage in the STZ-treated group (i.e., the diabetes-induced group). The expression of HSP60 and HSP70 was lower in the STZ group that received CrHis than in the group that did not. No significant effect of CrHis supplementation was detected in regard to the overall measured parameters in the control group.

CONCLUSIONS

Chromium histidinate significantly decreased lipid peroxidation levels and HSP expression in the kidneys of experimentally induced diabetic rats. This study supported the efficacy of CrHis in reducing renal risk factors and impairment because of diabetes.

Genistein and daidzein prevent diabetes onset by elevating insulin level and altering hepatic gluconeogenic and lipogenic enzyme activities in non-obese diabetic (NOD) mice

BACKGROUND

Non-obese diabetic (NOD) mice are regarded as being excellent animal models of human type 1 diabetes or insulin dependent diabetes (IDDM). This study investigated the beneficial effects of genistein and daidzein on IDDM, an autoimmune disease.

METHODS

Female NOD mice were divided into control, genistein (0.02%, w/w) and daidzein (0.02%, w/w) groups. Blood glucose level, plasma biomarkers, hepatic glucose and lipid regulating enzyme activities and pancreas immunohistochemistry analysis were examined after a 9-week experimental period.

RESULTS

Blood glucose levels of genistein and daidzein groups were 40 and 36% of control value at the end of study (9th week). The genistein and daidzein supplements increased insulin/glucagon ratio and C-peptide level with preservation of insulin staining beta-cell of pancreas in the NOD mice. In the liver, genistein and daidzein supplements resulted in lowering glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) activities, while increasing two lipogenic enzymes activities, malic enzyme and glucose-6-phosphate dehydrogenase (G6PD), compared to the control group. Significantly, genistein and daidzein supplementation lowered the activities of fatty acid beta-oxidation and carnitine palmitoyltransferase (CPT) in these mice. Genistein and daidzein also improved plasma triglyceride and free fatty acid (FFA) concentrations compared to the control group.

CONCLUSIONS

These results suggest that genistein and daidzein play important roles in regulation of glucose homeostasis in type 1 diabetic mice by down-regulating G6Pase, PEPCK, fatty acid beta-oxidation and CPT activities, while up-regulating malic enzyme and G6PD activities in liver with preservation of pancreatic beta-cells. The supplementation of genistein and daidzein are seemingly helpful for preventing IDDM onset.

Chromium picolinate does not produce chromosome damage

Chromium picolinate (CrPic) is used as a dietary supplement and has beneficial effects in reducing diabetes risk factors. The present study evaluated the cytogenetic effects of CrPic in bone marrow cells of Sprague-Dawley rats (5 animals/sex/group). Test animals were dosed orally with 33, 250 or 2000 mg/kg of CrPic, which corresponded to doses of 4.1, 30.8 and 246 mg/kg of chromium. The lowest dose of CrPic, 33 mg/kg is estimated to be the human equivalent for a 50 kg person (200 mcg Cr). The animals were dosed once, and sacrificed either 18 or 42 hours (h) later. The mitotic index was determined for each rat. Metaphase cells (50 or 100/rats) were examined for interstitial deletions, chromatid and chromosome gap, breaks or other anomalies. The average percentage of damaged cells at 18 h in vehicle treated males and females were 1.2% and 0.6%, respectively. The mean values at 18 h for doses of 33, 250 and 2000 mg/kg, were 0.4%, 0.8%, 0.4% for males and 0.6%, 0.2% and 0.6% for females, respectively. At 42 h, the mean values for vehicle treated males and females were 0.4% and 0.2%, respectively. For doses of 33, 250 and 2000 mg/kg at 42 h the average percent damage was 14%, 0.8% and 0.4% for males and 0.2%, 0.2% and 0.0% for females, respectively. None of these values were statistically increased compared to the vehicle controls. The positive control Cyclophosphamide (CPM) induced a significant increase in chromosomal damage at 18 h averaging 30% in males and 37% in females, respectively (p<0.001). In the current study CrPic did not induce chromosomal damage in bone marrow cells at single doses of 33, 250 and 2000 mg/kg of body weight and thus there was no indication of any toxicity of CrPic.

Effect of chronic chromium picolinate in animal models of anxiety and memory

Diabetes mellitus is associated with certain neurological problems such as depression, anxiety, memory impairment, etc. As chromium picolinate (CrP), a widely used trace element is shown to have beneficial effects in diabetes and depression, we investigated its effects on elevated plus maze and spontaneous alternation behavior paradigm as a measure of anxiety and memory, respectively. CrP (8 microg/mL in drinking water) significantly increased percentage preference to open arm in elevated plus maze in diabetic and normal rats. However, no significant changes were observed in percentage alternation after CrP chronic treatment. The possible anxiolytic effect of CrP might be related to its effect on serotonergic transmission.

Effect of chromium on carbohydrate and lipid metabolism in a rat model of type 2 diabetes mellitus: the fat-fed, streptozotocin-treated rat

Chromium supplements are widely used as an alternative remedy for type 2 diabetes mellitus (T2DM). In vitro study findings show that chromium picolinate (CrPic) may improve insulin sensitivity by enhancing intracellular insulin receptor. In this study, we evaluated the metabolic effects of CrPic in a rat model of T2DM. Male Sprague-Dawley rats (n = 45, 8 weeks old) were divided into 3 groups. The controls (group I) received a standard diet (12% of calories as fat); group II received a high-fat diet (HFD; 40% of calories as fat) for 2 weeks and then were intraperitoneally injected with streptozotocin (STZ, 40 mg/kg; HFD/STZ) on day 14; group III rats were given group II diets with the addition of 80 microg CrPic per kilogram body weight per day. The addition of CrPic in the group III treatment lowered glucose by an average of 63% (P < .001), total cholesterol by 9.7% (P < .001), and triglycerides by 6.6% (P < .001) compared with group II treatment. Compared with group II, CrPic treatment also lowered free fatty acid levels by 24% (P < .001), blood urea by 33% (P < .05), and creatinine level by 25% (P < .01), and reduced the severity of glomerular sclerosis (P < .0001). Histopathologic findings suggest that the CrPic-treated group had normal renal tubular appearance compared with the HFD/STZ-treated group. Normal appearance of hepatocytes was observed in the CrPic-treated group. These results showed that CrPic has marked beneficial effects against microvascular complications. In conclusion, HFD/STZ rats provide a novel animal model for T2DM. Further treatment with CrPic for 10 weeks significantly ameliorated changes in metabolic risk factors including favorable changes in histopathology of the liver, kidney, and pancreas, suggesting its potential role in the management of diabetes.

Chromium-picolinate induced ocular changes: Protective role of ascorbic acid

Chromium-picolinate (Cr-picolinate) is a popular nutritional supplement; however its safety has been questioned with regard to its ability to act as a clastogen. The aim of the present work was to evaluate the biochemical, histological and morphological changes in the cornea and lens following oral administration of Cr-picolinate and the possible protective effect of Vitamin C. Ninety male Sprague-Dawley rats were divided into five groups included the control group, the groups treated with Cr-picolinate (0.8 and 1.5 mg/100 g b.w.) alone or in combination with Vitamin C (0.5 mg/100 g b.w.) for 8 weeks. The results indicated that the high dose of Cr-picolinate induced a significant decrease in SOD, GSH, Na(+)-, K(+)-ATPase levels, and a significant increase in MDA level. Severe morphological and histological changes in the cornea and lens accompanied with a decrease in the total soluble protein of the lens homogenate and changes in the crystalline fractions in lens. Vitamin C supplementation succeeded to restore these changes to great extent. It could be concluded that consumption of Cr-picolinate for a long time induced several hazards to cornea and lens. Supplementation with extra amounts of Vitamin C may be useful to restrain the Cr-picolinate induced ocular changes.

Antidiabetic effect of Ceiba pentandra extract on streptozotocin-induced non-insulin-dependent diabetic (NIDDM) rats

The aim of this work was to investigate the effect of daily oral administration of root bark methylene chloride/methanol extract of Ceiba pentandra (Linn) in streptozotocin-induced type-2 diabetic rats, and the effect of this treatment on the physiological and metabolic parameters that are related in diabetic animals. The diabetic rats were separated into four groups and each given the following samples by gavage, daily for 28 days: vehicle (diabetic control), Ceiba pentandra extract at the dose of 40 mg/kg, Ceiba pentandra extract at the dose of 75 mg/kg and glibenclamide (5 mg/kg). All the parameters were also determined in healthy (non diabetic) rats for comparison. The methylene chloride/methanol extract of Ceiba pentandra treatment significantly reduced the intake of both food and water as well as the levels of blood glucose, serum cholesterol, triglyceride, creatinine and urea, in comparison with diabetic controls. The treatment also improves impaired glucose tolerance but no effect was observed in the level of hepatic glycogen. The effect of Ceiba pentandra (40 mg/kg) was more prominent when compared to glibenclamide in lowering blood glucose, with the added benefit of considerably reducing serum cholesterol and triglyceride concentrations. The results of this experimental animal study indicated that Ceiba pentandra possesses antidiabetic activity; and thus is capable of ameliorating hyperglycaemia in streptozotocin-induced type-2 diabetic rats and is a potential source for isolation of new orally active agent(s) for anti-diabetic therapy.

Effect of Chromium Picolinate on Modified Forced Swimming Test in Diabetic Rats: Involvement of Serotonergic Pathways and Potassium Channels

Depression occurs frequently in patients with diabetes mellitus. Chromium picolinate, an essential trace element is recommended for diabetes and also has been reported to benefit depression, but its mechanism is still debated. To investigate the mechanism, we studied its effects on serum insulin, serum glucose and on modified forced swimming test, a behavioural paradigm for depression in rats. The study involving co-administration of sub-active doses of glimepiride, a K(+) channel blocker and chromium picolinate on blood glucose levels and modified forced swimming test was also performed to probe any role of K(+) channels in its antidiabetic and antidepressants effects. Streptozotocin (55 mg/kg, intraperitoneally) was injected in rats to induce diabetes (Type 1). After a week, chromium picolinate (8 microg/ml in drinking water) was administered for 4 weeks. Normal rats received similar drug treatment. The sub-active doses of chromium picolinate (4 microg/ml in drinking water) and glimeperide (2.5 mg/kg, orally) were co-administered and their effects on modified forced swimming test and on glucose levels were measured. Chromium picolinate (8 microg/ml in drinking water) produced hypoglycaemia in diabetic and normal rats. It had no effects on the streptozotocin-induced reduction in insulin levels. Chromium picolinate (8 microg/ml in drinking water) increased swimming with subsequent decrease in immobility. The sub-active doses of chromium picolinate and glimeperide showed significant additive effects in modified forced swimming test and reduction in serum glucose concentrations, though statistically insignificant. In conclusion chromium picolinate shows antidepressant action on modified forced swimming test affecting only swimming that suggests serotonergic pathways involvement. The additive effects on swimming in modified forced swimming test and reduction in serum glucose levels shows involvement of K(+) channels in antidiabetic and antidepressant actions of chromium picolinate.

Chromium picolinate does not produce chromosome damage in CHO cells

Chromium picolinate (CrPic, Chromax) is a dietary supplement that has been commercially available for the past two decades. CrPic has potential benefits for reducing insulin dependence in diabetics by increasing sensitivity of insulin receptors and in stimulating insulin binding. In this study, CrPic was tested for its ability to produce chromosomal aberrations in vitro using Chinese hamster ovary K1 (CHO) cells. CHO cells were exposed to a range of cytotoxic to non-cytotoxic concentrations of CrPic for 4 or 20h in the absence of metabolic (S9) activation or for 4h in the presence of S9 activation. CrPic was solubilized with dimethyl sulfoxide (DMSO) to attain the highest possible solubility for maximizing the test doses. Cells were treated with 96.25, 192.5, 385 or 770 microg/mL of CrPic for 4 h in the presence of S9 activation, and for 4 or 20 h in the absence of S9 activation. A distinct precipitate of CrPic was evident in the cell culture medium at 770 microg/mL, which was the highest dose tested. Results showed no statistically significant increases in structural or numerical chromosome aberrations were produced at any test dose level with CrPic in 4-h treatments up to a precipitating dose of 770 microg/mL in either the presence or absence of S9 activation. Additionally no aberrations were observed up to 385 microg/mL (the maximum analyzable dose) following treatment for 20 h in the absence of S9 activation. The percentage of cells with structural or numerical aberrations in CrPic treated cultures was not statistically different (p>0.05) from that quantified in controls at any dose level. The absence of significant differences from control levels demonstrates that CrPic did not induce structural or numerical chromosome aberrations up to doses that were insoluble in the culture medium.