Untreated Diabetes Mellitus Rats Research Articles

Antidiabetic properties of Tarchonanthus camphoratus in fructose-induced diabetic Wistar rats

Tarchonantus camphoratus (TC) has been used traditionally to manage diabetes mellitus (DM) in Kenya but its efficacy has not been scientifically evaluated. This study aimed at evaluating the antidiabetic properties of TC crude leaf extract in diet-induced diabetic Wistar rats. DM was induced using high fructose (25% w/v) in drinking water for 12 weeks. Rats were divided into five groups (n=7): Groups I: normal control; II; diabetic untreated; III, IV & V; diabetic treated (21 days) with metformin (100 mg/kg.bw/day), 300 and 600 mg/kg.bw/day of TC extract respectively. Fasting body weights and blood glucose levels were monitored weekly. Oral glucose tolerance test, serum lipid profile, creatinine, urea, alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total proteins (TP), C-reactive protein (CRP), albumin (ALB) and triglyceride (TG) mass in skeletal muscle were analysed at end of the study. Qualitative phytochemical analysis was done using standard procedures. Diabetic untreated rats had significantly higher body weights (p ˂0.05) compared to other groups. There was a significant reduction in fasting blood glucose in TC treatment groups compared to untreated controls. Increased glucose tolerance was observed in treated groups. TC extract significantly improved fructose-induced hypertriglyceridemia compared to DM groups. ALP, ALT, and CRP were significantly lowered while TP and ALB were elevated in the extract treated rats compared with untreated DM rats. DM group also exhibited significantly higher skeletal muscle TG mass when compared to normal control and diabetic treated groups. The phytochemical-rich TC leaf extract therefore possess potential alternative medicine for DM management.

Short-Term Treatment of Metformin and Glipizide on Oxidative Stress, Lipid Profile and Renal Function in a Rat Model with Diabetes Mellitus

Background: Oxidative stress, lipid profile and renal functions are well-known conventional risk factors for diabetes mellitus (DM). Metformin and gliclazide are popularly used monotherapy drugs for the treatment of DM. Aims: This study aims to assess the short-term treatment of single and dual therapy of glipizide/metformin on oxidative stress, glycemic control, serum lipid profiles and renal function in diabetic rats. Methods: DM was induced in rats with streptozotocin (STZ), then five different treatments were applied, including group I (untreated healthy control), group II (diabetic and untreated), group III (diabetic and treated with metformin), group IVI (diabetic and treated with glipizide) and group V (diabetic and treated with a combination of metformin and glipizide. Lipid peroxidation (LPO), nitric oxide (NO), total antioxidant capacity (TAC), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), total cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), creatinine and urea were measured. Results: Compared to the untreated DM group, FBG and HbA1c were significantly reduced in the DM groups (p < 0.01) treated with metformin (159.7 mg/dL & 6.7%), glipizide (184.3 mg/dL & 7.3%) and dual therapy (118 mg/dL & 5.2%), respectively. Treatment with dual therapy and metformin significantly decreased LPO and NO levels but increased TAC in diabetic rats more than glipizide compared to untreated diabetic rats. Furthermore, metformin (19.8 mg/dL, p < 0.001), glipizide (22.7 mg/dL, p < 0.001), and dual therapy (25.7 mg/dL, p < 0.001) significantly decreased urea levels in the treated rats compared to untreated DM rats (32.2 mg/dL). Both drugs and their combination exhibited a substantial effect on total cholesterol, HDL, LDL and atherogenic index. Conclusions: These results suggest that the therapeutic benefits of metformin and glipizide are complementary. Metformin exhibited superior performance in improving glycemic control and decreasing oxidative stress, while glipizide was more effective against dyslipidemia. These findings could be helpful for the treatment of future vascular patients, antilipidemic medicines and antioxidant therapy to improve the quality of life.

Urethral dysfunction and alterations of nitric oxide mechanisms in streptozotocin-induced diabetic rats with or without low-dose insulin treatment

AimsTo establish an animal model of diabetes mellitus (DM) with moderately elevated blood glucose levels, and to examine the nitric oxide (NO) mechanism controlling urethral function in streptozotocin (STZ)-induced DM rats. Main methodsFemale Sprague-Dawley rats were used. DM was induced by intraperitoneal injection of STZ (65 mg/kg) and some of them received subcutaneous implantation of a low-dose insulin pellet. Voiding behavior was evaluated in metabolic cages. Isovolumetric cystometry and urethral perfusion pressure (UPP) were then evaluated under urethane anesthesia, during which L-arginine (100 mg/kg) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50 mg/kg) were administered intravenously. In vitro urethral activity was also tested by organ bath muscle strip studies. Key findingsUPP changes and high-frequency oscillation (HFO) were significantly (P < 0.05) smaller in 8-weeks DM rats vs. normal control (NC) rats or insulin-treated DM rats, which showed reductions in urine overproduction and voided volume per micturition vs. untreated DM rats. UPP nadir was decreased by L-arginine in NC and insulin-treated DM groups, and decreased by L-NAME in all groups. Five of 6 untreated DM rats showed a detrusor-sphincter dyssynergia pattern after L-NAME. In in vitro studies, the relative ratio of L-NAME-induced reductions of urethral relaxation against pre-drug urethral relaxation was significantly smaller in DM vs. NC rats (P < 0.05). SignificanceLow-dose insulin-treated DM rats would be a useful model for studying natural progression of DM-induced lower urinary tract dysfunction. The impaired NO-mediated urethral relaxation mechanisms play an important role in DM-induced urethral dysfunction, which could contribute to DM-induced inefficient voiding.

MiRNA array and oxi-proteome analyses reveal posttranscriptional actions of T3 on diabetic rats’ liver that could improve glycemia control

Diabetes mellitus (DM) has a multifactorial etiology including diverse molecular alterations comprising transcriptional and posttranslational mechanisms. Studies from our group have shown that DM-induced rats present primary hypothyroidism and that 3,5,3´ Triiothyronine (T3) treatment improves their glycemia control by reducing inflammatory cytokines expression in insulin-responsive tissues, and hepatic glucose production. Taking into account the complexity of DM etiology and treatment and the different mechanisms by which T3 induces its effects, this study aimed to evaluate the involvement of posttranscriptional mechanisms in the alterations of DM rats’ liver subjected to T3 treatment using miRNA PCR array and oxi-proteome analyses. DM was induced in 8-week-old Wistar rats by alloxan injection, and a subset of DM rats was treated with T3 (0.15 μg/kg BW) for 28 days. miRNA PCR array was used to analyze the expression of a set of 84 miRNAs implicated in DM, while oxidative damage of liver proteins, represented by protein carbonylation, was determined by 2D-DIGE method followed by mass spectrometry. This study identified by PCR array and validated by qPCR 10 de-regulated miRNAs (miR-21-5p, miR-29 a-c; miR-34a-5p; miR-96-5p; miR-122; miR-183-5p; miR-184 and miR-320) involved in insulin, glucose and inflammatory cellular response, additionally a decrease in oxidative damage of GCC2, CTH, CPS1, DMGDH, RGN and HP proteins related to glucose metabolism control, hormonal cellular response, and apoptosis processes in T3-treated vs untreated DM rats (P<0,05). The results indicate that T3 acts by different posttranscriptional mechanisms, favoring the improvement of glucose homeostasis of DM rats.

Beneficial Effect of Intense Pulsed Light on the Wound Healing in Diabetic Rats.

Wound healing in diabetes mellitus (DM) patients is one of the major health concerns globally. Intense pulsed light (IPL) has been widely used in cosmetic dermatology via mechanisms involving fibroblast stimulation, collagen synthesis, and dermal remodeling, which are events that also occur during the process of wound healing. This present study was aimed to evaluate the possible beneficial effect of IPL on the wound healing in diabetic rats. Diabetes was induced in Sprague-Dawley rats using streptozotocin. The rats were randomly divided into four groups: normal group, DM only group, DM rats with IPL treatment 2 weeks before wounding (DM + IPL-Pre group), and DM rats with concurrent IPL exposure and wounding (DM + IPL-Con group). The wounds were created on the dorsal skin of rats. Wound closure rate, collagen deposition, and angiogenesis were assessed. There were no significant differences in the wound closure rate and mean time to wound closure between IPL-treated diabetic rats and normal rats. By contrast, delayed wound closure and prolonged mean time to wound closure were both noticed in DM only group. Enhanced collagen deposition and angiogenesis were observed in IPL-Pre, but not IPL-Con diabetic rats, as compared with untreated DM rats. Results of this study may provide novel insight into future preventive strategies using IPL for the management of wounds in diabetic patients. Lasers Surg Med. © 2019 Wiley Periodicals, Inc.

Evaluation of body weight, serum glucose level and oxidative stress parameters of diabetic rats administered phenolic aqueous leaf extract of Vitex doniana

Background: The present study evaluated the effect of phenolic aqueous leaf extract of Vitex doniana on body weight, serum glucose and oxidative stress parameters in diabetes mellitus (DM) rats.&#x0D; Methods: DM was induced in rats by intraperitoneal injection of 100 mg/kg alloxan monohydrate in phosphate buffered saline (PBS; pH = 7.4). A total of 36 adult male Wister albino rats were divided into 6 groups of 6 rats. The groups consist of normal untreated rats, untreated DM rats, DM rats treated with 500 mg/kg dimethylguanide (MetforminTM) and DM rats treated with 100, 200 and 400 mg/kg body weight of phenolic aqueous leaf extract of Vitex doniana. The rats were treated for 28 days. Serum glucose, malondialdehyde (MDA), glutathione (GSH) and ascorbic acid concentrations, and serum superoxide dismutase (SOD) and catalase (CAT) activities were measured using standard methods. The changes in body weight was also measured.&#x0D; Results: The results showed a significant reduction (p &lt; 0.05) in serum glucose and MDA concentration, whereas serum SOD, CAT activities, as well as GSH and ascorbic acid concentration were significantly elevated (p &lt; 0.05) in treated DM groups in a dose dependent manner.&#x0D; Conclusion: The results of the present study indicated that phenolic aqueous leaf extract of V. doniana promoted increased body weight, ameliorated DM and alleviated reduced antioxidant activities in alloxan-induced DM rats. Phenolic aqueous leaf extract of V. doniana could serve as a potential natural and safe remedy for the management of DM.&#x0D;

Silymarin ameliorates diabetic cardiomyopathy via inhibiting TGF-β1/Smad signaling.

Diabetic cardiomyopathy (DCM) is the leading cause of morbidity and mortality in diabetes mellitus (DM) patients. Previous studies have shown that the transforming growth factor-beta 1 (TGF-β1)/Smad signaling pathway plays a key role in the development of myocardial fibrosis in DCM. Silymarin (SMN) is used clinically to treat liver disorders and acts by influencing TGF-β1. However, the possible effects of silymarin on DCM remain to be elucidated. In our study, the DM animal model was induced by streptozotocin (STZ) injection. Fasting blood glucose level was measured, and the structure and function of the heart were measured by hematoxylin and eosin (H&E) and Masson staining, echocardiography, and transmission electron microscopy (TEM). Western blot was used to detect the expression of TGF-β1, Smad2/3, phosphorylation Smad2/3(p-Smad2/3), and Smad7. Our results showed that silymarin downregulated blood glucose level and significantly improved cardiac fibrosis and collagen deposition in DM rats detected by H&E, Masson staining, and TEM assays. The echocardiography results showed that silymarin administration attenuated cardiac dysfunction in DM rats. Additionally, compared with untreated DM rats, levels of TGF-β1 and p-Smad2/3 were decreased, whereas Smad7 was increased following silymarin administration. These data demonstrate that silymarin ameliorates DCM through the inhibition of TGF-β1/Smad signaling, suggesting that silymarin may be a potential target for DCM treatment.

Osthole alleviated diabetic neuropathic pain mediated by the P2X4 receptor in dorsal root ganglia

Diabetes mellitus (DM) is considered the primary cause of neuropathic pain. Osthole (7-methoxy-8[3-methylpent 2-enyl]coumarin) is a component extracted from Cnidium monnieri (L.) cusson plant seeds and has anti-inflammatory and anti-oxidative properties. The aim of the present study was to investigate the effects of osthole on diabetic neuropathic pain (DNP) involving the P2X4 receptor on satellite glial cells (SGCs) in the dorsal root ganglia (DRG) of type 2 diabetic rats. These data showed that the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in DM rats were lower than those in control rats. MWT and TWL in DM rats treated with osthole were higher compared with those in untreated DM rats. The expression levels of P2X4 mRNA and protein in the DRG of DM rats were higher compared with those in the control rats, while those in DM rats treated with osthole were significantly lower compared with those in the untreated DM rats. Osthole treatment decreased the co-expression levels of P2X4 and glial fibrillary acidic protein (GFAP) and reduced the up-regulated expression of interleukin-1 beta (IL-1β), tumour necrosis factor-α (TNF-α), brain-derived neurotrophic factor (BDNF) and phosphorylated-p38MAPK and enhanced the down-regulation of IL-10 in DM rats. Thus, osthole treatment may act on the P2X4 receptor to alleviate the mechanical and thermal hyperalgesia in DM rats.

P2Y12 shRNA treatment decreases SGC activation to relieve diabetic neuropathic pain in type 2 diabetes mellitus rats.

Diabetic neuropathic pain is a common complication of type 2 diabetes mellitus (DM). Activation of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) plays a crucial role in neuropathic pain through the release of proinflammatory cytokines. The P2Y12 receptor is expressed in SGCs of the DRG. In this study, our aim was to investigate the role of the P2Y12 receptor on the pathological changes in diabetic neuropathic pain. The present study showed that diabetic neuropathic pain increased mechanical and thermal hyperalgesia in type 2DM model rats. The results showed that the expression levels of P2Y12 messenger RNA (mRNA) and protein in DRG SGCs were increased in DM model rats compared with control rats. Glial fibrillary acidic protein (GFAP) and interleukin-1β (IL-1β) expression levels in the DRG were increased in DM rats. Upregulation of GFAP is a marker of SGC activation. Targeting the P2Y12 receptor by short hairpin RNA (shRNA) decreased the upregulated expression of P2Y12 mRNA and protein, coexpression of P2Y12 and GFAP, the expression of GFAP, IL-1β, and tumor necrosis factor-receptor 1in the DRG of DM rats, and relieved mechanical and thermal hyperalgesia in DM rats. After treatment with the P2Y12 receptor shRNA, the enhancing integrated OPTICAL density (IOD) ratios of p-P38 MAPK to P38 mitogen activated protein kinase (MAPK) in the DM rats treated with P2Y12 shRNA were significantly lower than that in the untreated DM rats. Therefore, P2Y12 shRNA treatment decreased SGC activation to relieve mechanical and thermal hyperalgesia in DM rats.

Doxazosin attenuates renal matrix remodeling mediated by anti-α1-adrenergic receptor antibody in a rat model of diabetes mellitus.

Diabetic nephropathy is a major complication of diabetes mellitus (DM). Recent studies suggest that immunological mechanisms have a key role in the pathogenesis of DM, therefore these mechanisms may be important targets for diabetes therapy. The present study evaluated the effects of anti-α1-adrenergic receptor antibody (α1-R Ab) mediation and doxazosin treatment in a rat model of DM. It was observed that levels of 24-h urinary protein, serum creatinine and transforming growth factor-β1 in DM were significantly increased after α1-R Ab mediation (all P<0.05). In addition, electron microscopy identified severe damage in the renal tissue microstructures of DM rats following α1-R Ab mediation, while only mild abnormalities were observed in that of healthy rats mediated with α1-R Ab and of untreated DM rats. No marked abnormalities were observed in the renal tissue of healthy blank controls. Furthermore, in DM rats treated with α1-R Ab mediation + doxazosin intervention, the expression of TGF-β1 significantly decreased, and renal functions and renal matrix remodeling were significantly improved, relative to untreated DM controls (P<0.01). These results suggest that α1-R Ab may be involved in renal matrix remodeling during DM, and that kidney protection during DM may be achieved through treatment with corresponding receptor antagonists.

Abstract WMP82: Exosomes Derived From Cerebral Endothelial Cells of Young Adult Rats Reduced Cognitive Deficits in Aged Diabetic Rats

Introduction: Diabetes mellitus (DM) is associated with cognitive decline and dementia in the elderly. The glymphatic system mediates clearance of the interstitial solutes in the brain by exchange of cerebrospinal and interstitial fluid (CSF and ISF). We recently demonstrated that DM in aged rat induces impairment of the glymphatic system and cognitive decline. Exosomes, membrane vesicles, mediate intercellular communication by transferring their cargo into recipient cells. The present study investigated whether cerebral endothelial exosomes (CEE) ameliorate glymphatic system impairment and improve cognitive function in aged DM rats. Methods and Results: DM was induced in male Wistar rats (13 months, n=48) by injection of nicotinamide and streptozotocin. Two months after DM, rats were treated with CEE (1x10 11 exosomes/rat, IV) twice a week for 4 weeks. Age matched DM and non-DM rats were used as controls. CEE were harvested from the cultured cerebral endothelial cells of health young adult rats. Exchanges of CSF and ISF were measured by intracisternal injection of fluorescent tracer, Texas Red-dextran (TR, 3kD). Confocal microscopic analysis of brain slices revealed a progressive slowdown of ISF clearance in the hippocampi, assessed by retention of TR starting at 2.5 fold at 2M (13±5 vs 5±3% of area) and increasing to 4 fold at 4M (21±4 vs 5±2%) of DM. Paravascular amyloid β (Aβ) accumulation was only detected at 4M of DM. The CEE treatment significantly (p&lt;0.05) reduced TR retention (10±4%) at 4M of DM and also decreased Aβ accumulation (2±1 vs 6±2/mm 2 ) and parenchymal fibrin deposition (9±5 vs 23±5/mm 2 ) compared to untreated DM rats. Moreover, the CEE treatment significantly improved hippocampal related learning and memory measured by the Morris Water Maze and odor-based novelty recognition for olfactory memory, without altering the glucose level. In vitro, cerebral endothelial cells isolated from 2M DM rats exhibited substantial dysfunction as measured by capillary-like tube formation and cell migration, whereas incubation with the CEE substantially reversed endothelial dysfunction. Conclusions: The CEE treatment reduces DM-induced glymphatic and cerebral endothelial dysfunctions, leading to improvement of cognitive function in aged DM rats.

Opuntia humifusa stems lower blood glucose and cholesterol levels in streptozotocin-induced diabetic rats

The Opuntia humifusa stem (OHSt) contains high levels of antioxidants including vitamin C, flavonoids, and polyphenols that may prove beneficial in treating diabetes mellitus. The objective of this study was to examine the hypothesis that intake of the OHSt regulates blood glucose levels and hypolipidemic responses in rats with diabetes mellitus induced by injection of streptozotocin. Forty Sprague-Dawley rats (6 weeks of age) were assigned to 5 groups: normal control, rats with streptozotocin-induced diabetes mellitus (DM), DM treated with OHSt 150 mg/kg per day, DM treated with OHSt 250 mg/kg per day, and DM treated with OHSt 500 mg/kg per day. Powdered OHSt was suspended in distilled water and administered orally through the sonde once daily. After 7 weeks of treatment, the fasting blood glucose and triglyceride levels of the OHSt groups were significantly lower when compared with the DM group (P < .05). Treatment with the OHSt also resulted in a significant decrease in serum total cholesterol and low-density lipoprotein cholesterol (P < .05). Decreases in both total cholesterol and low-density lipoprotein cholesterol were accompanied by a significant increase in serum high-density lipoprotein cholesterol (P < .05). Furthermore, levels of alanine aminotransferase and aspartate aminotransferase were significantly lower in the OHSt groups than in the DM group (P < .05). In addition, a significant increase in relative beta cell volume of pancreas was observed in rats treated with 500 mg/kg of OHSt when compared with the untreated DM rats (P < .05). The overall results suggest that the OHSt possesses potential hypoglycemic and hypolipidemic activity in streptozotocin-induced diabetic rats.

Resveratrol ameliorates early diabetic nephropathy associated with suppression of augmented TGF-β/smad and ERK1/2 signaling in streptozotocin-induced diabetic rats

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. The early changes in DN are characterized by an increased in kidney size, glomerular volume, and kidney function, followed by the accumulation of glomerular extracellular matrix, increased urinary albumin excretion (UAE), glomerular sclerosis, and tubular fibrosis. Resveratrol (RSV) has been shown to ameliorate hyperglycemia and hyperlipidemia in streptozotocin-induced diabetic rats. In the present study, we examined the beneficial effects of RSV on DN and explored the possible mechanism of RSV action.Male Sprague–Dawley rats were injected with streptozotocin at 65mg/kg body weight. The induction of diabetes mellitus (DM) was confirmed by a fasting plasma glucose level ≥300mg/dL and symptoms of polyphagia and polydipsia. The DM rats were treated with or without RSV at 0.75mg/kg body weight 3 times a day for 8 weeks. Animals were sacrificed and kidney histology was examined by microscopy. Urinary albumin excretion, glomerular hypertrophy and expressions of fibronectin, collagen IV, and TGF-β in the glomeruli were alleviated in RSV-treated DM rats, but not in untreated DM rats. In addition, RSV treatment reduced the thickness of the glomerular basement membrane (GBM) to the original thickness and increased nephrin expressions to normal levels in DM rats. Moreover, RSV inhibited phosphorylation of smad2, smad3 and ERK1/2 in diabetic rat kidneys. This is the first report showing that RSV alleviates early glomerulosclerosis in DN through TGF-β/smad and ERK1/2 inhibition. In addition, podocyte injuries of diabetic kidneys are lessened by RSV.

Protective effect of the daming capsule on impaired baroreflexes in STZ-induced diabetic rats with hyperlipoidemia

BackgroundThe Daming capsule (DMC) is a traditional Chinese medicine used to treat hyperlipoidemia. Both clinic trials and studies on animal models have demonstrated that DMC is beneficial against diabetic symptoms. Impairment of the baroreflex can cause life-threatening arrhythmias and sudden cardiac death in patients with diabetes mellitus (DM). This study was designed to elucidate the effects of DMC on baroreflexes in streptozocin (STZ)-induced diabetic rats with hyperlipoidemia.MethodsWistar rats were randomly divided into three groups: untreated controls, rats pretreated STZ and high lipids (a diabetes model or DM rats), and DM rats treated with DMC. The baroreflex sensitivity was examined during intravenous injection of phenylephrine (PE) or sodium nitroprusside (SNP) and quantified by the change in heart rate over the change in mean arterial blood pressure (ΔHR/ΔMABP). Morphological remodeling of baroreceptors was analyzed by transmission electron microscopy (TEM). The mRNA levels and expression of GluR2 and a GABAA receptor subunit were measured by quantitative RT-PCR and Western blotting.ResultsCompared to untreated DM rats, DMC significantly elevated the ratio of ΔHR/ΔMABP by enhancing the compensatory reduction in HR (-ΔHR) in response to PE-induced hypertension (+ΔMABP) (P < 0.05). In the presence of SNP, DMC increased the ΔMABP (P < 0.05). In addition, DMC markedly shortened the duration of blood pressure changes elicited by PE or SNP in DM rats compared to the untreated DM group (P < 0.05). Electron microscopy revealed disrupted myelin sheaths, swollen ER, and lysed mitochondria in the nucleus ambiguous (NAm) DM rats. These signs of neuropathology were largely prevented by treatment with DMC for 30 days. Treatment with DMC elevated both mRNA and protein level of GluR2 in the NAm of DM rats, but had no effect on GABAA receptor expression.ConclusionThe Daming capsule partially reversed the parasympathetic baroreflex impairment observed in STZ-induced diabetic rats with hyperlipoidemia. Treatment with DMC also prevented the degeneration of neurons and myelinated axons in the brain stem NAm and reversed the down-regulation of GluR2 mRNA. Rescue of NAm function may contribute to the medicinal properties of DMC in diabetic rats.

The Role of Nitric Oxide in the Urine Concentration Mechanism in Diabetic Rats

Diabetes mellitus (DM) results in osmotic diuresis and lowered levels of nitric oxide (NO). We examined how absence of NO affects transporters involved in urine concentration in DM. Sprague Dawley rats were injected with streptozotocin to induce DM. Control and DM rats were given L‐NAME, a non‐selective inhibitor of nitric oxide synthase. Urine osmolality was lower in DM rats, however in L‐NAME treated DM rats levels were similar to untreated and L‐NAME treated animals. L‐NAME treatment did not change urine output however L‐NAME treated DM rats produced less urine than untreated DM rats. UT‐A1 was increased in DM animals. L‐NAME treatment alone did not alter UT‐A1 abundance however DM‐treated rats had increased UT‐A1 expression but the abundance was less than untreated‐DM animals. AQP2 abundance was up both DM and DM‐L‐NAME rats compared to the control group. L‐NAME treatment had no effect on control or DM rat AQP2 expression. Similarly, NKCC2 expression was increased in both DM and DM‐L‐NAME rat. L‐NAME did not alter NKCC2 abundance compared to control or the DM untreated animal. Increased protein expression of UT‐A1, AQP2 and NKCC2 observed in DM rats provides a compensatory mechanism however lack of NO prevents the increase of UT‐A1 in DM but reduces urine osmolality and output. Data suggest that alteration of NO levels may be beneficial in treatment of polyuria occurring in DM.

Resveratrol ameliorates vasculopathy in STZ‐induced diabetic rats: role of AGE–RAGE signalling

Resveratrol (RSV) has been shown to ameliorate hyperglycaemia and hyperlipidaemia in streptozotocin-induced diabetic rats. In the present study, we examined the beneficial effects of RSV on diabetes mellitus (DM)-induced vasculopathy and explored its possible mechanism. Male Sprague-Dawley rats were injected with streptozotocin at 65 mg/kg body weight The induction of DM was confirmed by a fasting plasma glucose level > or = 300 mg/dL and symptoms of polyphagia and polydipsia. The DM rats were treated with or without RSV at 0.75 mg/kg body weight three times a day for 4-8 weeks. Animals were sacrificed and vessel wall histology was examined by microscopy. The vascular smooth muscle cell activation was assessed by the medial thickness, collagen deposition, and the expressions receptor for advanced glycation end product, NF-kappaB, proliferation cell nuclear antigen, and the levels of Erk1/2 phosphorylation. In RSV-treated DM rats, the vascular wall thickening, collagen deposition/cross-linking, and vascular permeability were all alleviated compared with that of the untreated DM rats. The vascular smooth muscle cell of the RSV-treated rats was characterized with less proliferation, lower NF-kappaB, and Erk1/2 activation, decreased proliferation cell nuclear antigen and receptor for advanced glycation end product expression. Moreover, the plasma fructosamine was significantly reduced in RSV-treated DM rats. RSV alleviated DM-induced vasculopathy through attenuation of advanced glycation end product-receptor for advanced glycation end product-NF-kappaB signalling pathway.

Effects of early insulin therapy on nuclear factor kappaB pathway in skeletal muscle of diabetes: experiment with rats

To investigate the effect of early insulin therapy on the nuclear factor kappaB (NF-kappaB) pathway and inflammatory cytokine responses in skeletal muscle in type 2 diabetes mellitus (DM). SD rats underwent intraperitoneal injection of streptozotocin to establish DM models and then divided into 5 groups: early un-treated group, early gliclazide treated group (receiving gliclazide since the third day after blood glucose increase for 3 weeks for 3 weeks), early insulin treated group (receiving insulin since the third day after blood glucose increase for 3 weeks for 3 weeks), late un-treated group, and late insulin treated group (receiving insulin since the fourth week after blood glucose increase for 3 weeks). By the end of treatment the rats were killed. Homogenate of skeletal muscle was made. The NF-kappaB P65 DNA binding was assayed by ELISA-based assay kit. Real time PCR was used to detect the mRNA expression levels of the gene of the cytokines: glucose transporter 4 (Glut4), inhibitor kappaB (IkappaBalpha), IL-1beta, IL-6, and tumor necrosis factor (TNF)-alpha. And Glut4 and IkappaBalpha protein expression levels were assayed by Western blotting. The Glut4 mRNA level in the skeletal muscle of the untreated DM rats decreased by 59% and the Glut4 protein level in the muscle cell membrane decreased by 69%. Insulin treatment and gliclazide treatment increased the Glut4 mRNA expression by 17% and 13% respectively, increased the Glut4 protein expression in cell membrane by 23% and 10% respectively, and decreased the Glut4 protein expression in the cytoplasm. In the DM rats the IkappaBalpha protein expression in the skeletal muscle was significantly lower (P < 0.05) and the NF-kappaB P65 DNA binding activity increased, and TNF-alpha, IL-1B, and IL-6 expression levels were up-regulated in comparison with the normal control group. Early treatment of insulin and gliclazide increased the IkappaBalpha protein expression, decreased the NF-kappaB P65 DNA binding activity and the TNF-alpha expression in the skeletal muscle. Early insulin treatment inhibits the NFkappaB activity and inflammatory cytokine responses in skeletal muscle that are involved in the amelioration of insulin resistance in type 2 DM. Such results may be due to indirect antiinflammatory effects of insulin relieving glucotoxicity and lipotoxicity in peripheral tissues.