Efficacy of Ginger (Zingiber officinale) in Ameliorating Streptozotocin-Induced Diabetic Liver Injury in Rats: Histological and Biochemical Studies

Ginger (Zingiber officinale) was reported to have an antioxidant, antidiabetic effect. This study was done to investigate its therapeutic effect against functional and structural alteration in liver of diabetic rat (intraperitoneal streptozotocin (STZ) in a dose of 60 mg/kg/bw). Thirty adult male rats (three-months-old and 250 g weight) were sorted into five groups (N=6). G1 used as control, G2 was diabetic rats without any treatment, G3 was diabetic rats given oral ginger in a dose of 500 mg/kg/bw, G4 was diabetic rats treated with metformin (500 mg/kg/bw) while G5 received ginger orally. The experiment lasts for six weeks, animals were anesthetized by ether, body weight was recorded for all animals. Blood was collected for further analysis of lipid profile, liver enzymes and total antioxidant. Liver was dissected, weighted and samples were processed for histopathological study. The results showed significant decrease of glaucous level and liver enzymes in ginger treated rats. Total antioxidant was preserved. Ginger lowered blood glucose, level, regained body weight and liver index to near normal values. Diabetes induced degenerative changes and micro-vesicular lipid deposition in hepatocytes with moderate portal area fibrosis. Ultrastructure study confirmed such changes beside demonstrating increased lipid deposition in fat storing cells. Ginger was found to ameliorate those changes in treated animals. Results were matching metformin effects. In conclusion, Ginger as a natural safe Herbal medication can be used to support liver functions in diabetic status.

Effects of allyl isothiocyanate on insulin resistance, oxidative stress status, and transcription factors in high-fat diet/streptozotocin-induced type 2 diabetes mellitus in rats

Allyl isothiocyanate (AITC), a dietary phytochemical found in some cruciferous vegetables, is commonly used as an antimicrobial, anticancer, and antioxidant agent. In the present study, we investigated the effects of AITC on insulin resistance and transcription factors in a diabetic rat model. A total of 42 Wistar rats were divided into six groups and orally treated for 12 weeks as follows: (i) control; (ii) AITC (100 mg/kg body weight [BW]); (iii) high fat diet (HFD); (iv) HFD + AITC (100 mg/kg BW); (v) HFD + streptozotocin (STZ, 40 mg/kg BW); and (vi) HFD + STZ + AITC. Administration of AITC reduced blood glucose, total cholesterol, triglycerides, and creatinine levels, but increased (P < 0.001) total antioxidant capacity. In AITC-treated rats, the glucose transporter-2, peroxisome proliferator-activated receptor gamma, p-insulin receptor substrate-1, and nuclear factor erythroid-derived 2 in the liver and kidney were increased while nuclear factor-kappa B was downregulated (P < 0.05). In conclusion, AITC possesses antidiabetic, antioxidant, and anti-inflammatory activities in HFD/STZ-induced T2DM in rats. These findings may further justify the importance of AITC in phytomedicine.

DIBc, a nanochelating-based nano metal-organic framework, shows anti-diabetic effects in high-fat diet and streptozotocin-induced diabetic rats

Aims

Despite daily increase in diabetic patients in the world, currently approved medications for this disease, at best, only reduce its progression speed. Using novel technologies is a solution for synthetizing more efficient medicines. In the present study, we evaluated anti-diabetic effects of DIBc, a nano metal–organic framework, which is synthetized based on nanochelating technology.

Methods

High-fat diet and streptozotocin-induced diabetic rats were treated by DIBc or metformin for 6 weeks.

Results

DIBc decreased plasma glucose, triglyceride, cholesterol, high-density lipoprotein, and low-density lipoprotein compared with diabetic and metformin groups. In DIBc-treated rats, significant homeostasis model assessment of insulin resistance index, malondialdehyde, and tumor necrosis factor-α decrease was observed. H&E staining showed increased islet number and area in DIBc-treated rats compared with diabetic controls.

Conclusion

The results showed anti-diabetic effects of nanochelating-based framework. So DIBc, as a nano structure, has the capacity to be evaluated in future studies as a novel anti-diabetic agent.

Glycemia Lowering Effect of an Aqueous Extract of Hedychium coronarium Leaves in Diabetic Rodent Models

Hedychium coronarium has a long history of use worldwide as a food and in folk medicine. In this study, we aimed to investigate the effect of an aqueous extract of H. coronarium leaves (HC) on type 2 diabetes mellitus (T2DM). Two types of animal models were used in this study: Streptozotocin (STZ)-induced T2DM (Wistar rats; N = 8) and C57BKSdb/db mice (N = 5). After treatment with HC for 28 days, glucose tolerance improved in both of the diabetic animal models. As significant effects were shown after 14 days of treatment in the STZ-induced T2DM model, we carried out the experiments with it. After 28 days of treatment with HC, the levels of cholesterol, triglyceride, high-density lipoprotein, and low-density lipoprotein were significantly improved in the STZ-induced T2DM model. The lesions degree of islet β-cells was decreased after the HC treatment. Although the insulin level increased moderately, the aldosterone level was significantly decreased in the HC-treated groups, suggesting that aldosterone might play an important role in this effect. In summary, HC is a natural product and it is worth exploring its effect on T2DM.

Protective Effects of 5-HT1A Receptor Inhibition and 5-HT2A Receptor Stimulation Against Streptozotocin-Induced Apoptosis in the Hippocampus

INTRODUCTION

Intracerebroventricular administration of streptozotocin (icv-STZ) induced apoptosis changes in neurons similar to Alzheimer's disease. The serotonergic system via its receptor involved in survival of neurons. The present study examined the ability of selective 5-HT1A receptor antagonist (NAD-299) and 5-HT2A receptor agonist (TCB-2) to attenuate the apoptosis caused by the icv-STZ in the rat.

METHODS

The icv-STZ (3 mg/kg, 10 μL, twice) induced neuronal loss in the hippocampus of adult male rats. Animals were divided into naive control, sham-operated, STZ+saline (1 μL, icv), STZ+NAD-299 (5 μg/μL, icv), STZ+TCB-2 (5 μg/μL, icv), and STZ+NAD-299+TCB-2 (5 μg/μL of any agent, icv) groups. Following the 35 days' treatment period, neuronal apoptosis was detected using the Tunnel. Cells with morphological features of apoptotic cell were contended by microscopy.

RESULTS

TCB-2 and NAD-299 administration decreased number of apoptotic neurons in the treatment group compared with the STZ group. Combined treatment of STZ rat with NAD+TCB more decreased number of apoptotic cells in compare to TCB-2 or NAD-299 treated STZ groups.

CONCLUSION

Treatment with 5-HT1A receptor antagonist or 5-HT2A receptor agonist diminished apoptosis. The beneficial effect of 5HT1A receptor inhibition was potentiated with activation of 5-HT2A receptor in prevention of apoptosis in hippocampus.

[The prospective of using plant polyphenols as functional food ingredients]

In this review we briefly discuss the publications dedicated to experimental evaluation of hypoglycemic, hypolipidemic and antioxidant properties of different plant polyphenols. The stages of preclinical studies of their efficacy are presented: in silico studies with molecular docking methods and in vivo studies with the use of genetic and medicamental models of type 2 diabetes. The results of own studies present the substantiation of prospects of using the plant polyphenol extracts as functional food ingredients for diet therapy and treatment of patients with type 2 diabetes. It was shown using genetic fatty Zucker rats model that extract consumption led to lower blood glucose level, had beneficial effect on glucose sensitivity and also improved the reaction of insulin-sensitive tissues on exogenous injection of glucose and insulin. Hypoglycemic and hypolipidemic properties of bilberry leaves extract were characterized on male Wistar rats model of carbohydrate metabolism disorder (streptozotocin injection accompanied with consumption of 10% fructose solution). The results of previous studies showed the beneficial effects of bilberry leaves extract on carbohydrate metabolism and determined the task to enhance the efficacy of developed polyphenol ingredient by the way of sorption on protein food matrix - brown buckwheat flour. Thus, a brief review of presented in this article results of foreign and domestic experimental studies shows the prospect of using the individual plant polyphenols and polyphenol plant extracts as phytonutrients for diet therapy and treatment of diseases associated with disorders of carbohydrate and lipid metabolism.

Effects of hCG on reduced numbers of hCG receptors in the prefrontal cortex and cerebellum of rat models of Alzheimer's disease

Age-associated changes in the levels of luteinizing hormone and human chorionic gonadotropin (hCG) are potential risk factors for Alzheimer's disease (AD); hCG concentration is related to the incidence of AD. The highest density of hCG receptors is in zones of the brain that are vulnerable to AD and streptozotocin (STZ) can decrease the density of this receptor. We investigated the effects of different doses of hCG on hCG receptor density in the prefrontal cortex and cerebellum in a rat model of STZ-induced AD. AD was induced by intracerebroventricular injection of 3 mg/kg STZ. The resulting AD rats were treated for 3 days with 50, 100 or 200 IU/200 μl hCG, or with saline as a control. Sections of prefrontal cortex and cerebellum were stained immunohistochemically and hCG receptor-immunoreactive (ir) neurons were counted. STZ injected into the lateral ventricles of rat brains reduced the density of hCG receptor-ir neurons in the prefrontal cortex and cerebellum. hCG administration resulted in a significant dose-dependent increase in the number of hCG receptor-ir neurons in the prefrontal cortex and cerebellum. The maximum increase in the number of receptors occurred following the 200 IU dose of hCG. Administration of hCG ameliorated the lowered density of hCG receptor-ir neurons in the cerebellum and prefrontal cortex in STZ-induced AD rats.

Influence of Porphyromonas gingivalis in gut microbiota of streptozotocin-induced diabetic mice

OBJECTIVES

Increasing evidence suggests that periodontitis can exacerbate diabetes, and gut bacterial dysbiosis appears to be linked with the diabetic condition. The present study examined the effects of oral administration of the periodontopathic bacterium, Porphyromonas gingivalis, on the gut microbiota and systemic conditions in streptozotocin-induced diabetic mice.

MATERIALS AND METHODS

Diabetes was induced by streptozotocin injection in C57BL/6J male mice (STZ). STZ and wild-type (WT) mice were orally administered P. gingivalis (STZPg, WTPg) or saline (STZco, WTco). Feces were collected, and the gut microbiome was examined by 16S rRNA gene sequencing. The expression of genes related to inflammation, epithelial tight junctions, and glucose/fatty acid metabolism in the ileum or liver were examined by quantitative PCR.

RESULTS

The relative abundance of several genera, including Brevibacterium, Corynebacterium, and Facklamia, was significantly increased in STZco mice compared to WTco mice. The relative abundances of Staphylococcus and Turicibacter in the gut microbiome were altered by oral administration of P. gingivalis in STZ mice. STZPg mice showed higher concentrations of fasting blood glucose and inflammatory genes levels in the ileum, compared to STZco mice.

CONCLUSIONS

Oral administration of P. gingivalis altered the gut microbiota and aggravated glycemic control in streptozotocin-induced diabetic mice.

Hyperactivation of the hypothalamo-pituitary-adrenocortical axis in streptozotocin-diabetic gerbils (Gerbillus gerbillus)

This study was designed to investigate the HPA-axis impairment in the streptozotocin (STZ)-diabetic gerbils (Gerbillus gerbillus). Twenty-six male gerbils (body weight ~27 g) were divided into 3 groups: vehicle control (n = 10), 2 days of diabetes (n = 09) and 30 days of diabetes (n = 07). The latter 2 groups received an intraperitoneal injection of STZ (150 mg/kg of body weight). At 2 and 30 days of diabetes, streptozotocin-diabetic gerbils underwent a retro-orbital puncture for assessment of biochemical and hormonal parameters. Subsequently the animals were decapitated and the adrenal glands were removed, weighed and processed for light microscopy and stereology. Nondiabetic control gerbils that had been injected with citrate buffer were examined as a comparison. At 2 days of diabetes, STZ gerbils exhibited symptoms that are characteristic of human diabetes type 1. The adrenal gland showed significant increase in weight, associated with a larger cortex layer, hypertrophy of the fasciculate cells and a significant decrease in the nucleocytoplasmic index. These changes were associated with higher plasma ACTH and cortisol concentrations compared to nondiabetic controls. At 30 days postdiabetes, ACTH levels remained elevated, whereas cortisol levels decreased compared to the early stage of diabetes. Histological analysis revealed the existence of a band of connective tissue (collagen) that separates the cortical and medullary zones and is not present in humans or laboratory rodents, which represents a striking change seen throughout the disease. STZ-induced diabetes mellitus in Gerbillus gerbillus resulted in hyperactivation of the HPA axis in the early stages of diabetes mellitus which did not persist into the final stages of the disease, suggesting a possible reduction in adrenocortical sensitivity over time.

Chronic insulinopenia/hyperglycemia decreases cannabinoid CB1 receptor density and impairs glucose uptake in the mouse forebrain

Both endocannabinoids and insulin regulate peripheral and cerebral glucose homeostasis via convergent signaling pathways that are impacted by diabetes. Here we asked how glucose metabolism and important facets of insulin signaling are affected in the forebrain of cannabinoid CB₁ receptor knockout mice (CB₁R-KO) and their wild-type (WT) littermates, seven weeks after the induction of insulinopenia/hyperglycemia (diabetes) with intraperitoneal streptozotocin injection. Sham-injected animals served as control. Diabetes caused milder weight loss in the WT mice compared to the phenotypically ˜11% leaner CB₁R-KO, while hyperglycemia was similar. Resting [³H]deoxyglucose uptake was significantly reduced by ˜20% in acute ex vivo frontocortical and hippocampal slices obtained from both the sham-injected CB₁R-KO and the diabetic WT mice. Surprisingly, the third cohort, the diabetic CB₁R-KO showed no further impairment in glucose uptake, as compared to the sham-injected CB₁R-KO. Depolarization-induced [³H]deoxyglucose uptake was proportional to the respective resting values only in the cortex in all four cohorts. The dissipative metabolism of [¹⁴C]-U-glucose remained largely unaffected in all cohorts of animals. However, diabetes reduced cortical CB₁R density by ˜20%, as assessed by Western blotting. Albeit the changes in insulin signaling did not reflect the glucose uptake profile in each cohort, there were significant interactions between diabetes and genotype. In conclusion, a chronic decrease or lack of CB₁R expression reduces glucose uptake in the mouse brain. Additionally, diabetes failed to cause further impairment in cerebral glucose uptake in the CB₁R-KO. These suggest that diabetic encephalopathy may be in part associated with lower CB₁R expression.

Treatment With Naringenin Elevates the Activity of Transcription Factor Nrf2 to Protect Pancreatic β-Cells From Streptozotocin-Induced Diabetes in vitro and in vivo

Chronic hyperglycemia and unusually high oxidative stress are the key contributors for diabetes in humans. Since nuclear factor E2-related factor 2 (Nrf2) controls the expression of antioxidant- and detoxification genes, it is hypothesized that targeted activation of Nrf2 using phytochemicals is likely to protect pancreatic β-cells, from oxidative damage, thereby mitigates the complications of diabetes. Naringenin is one such activator of Nrf2. However, it is currently not known whether the protective effect of naringenin against streptozotocin (STZ) induced damage is mediated by Nrf2 activation. Hence, the potential of naringenin to activate Nrf2 and protect pancreatic β-cells from STZ-induced damage in MIN6 cells is studied. In MIN6 cells, naringenin could activate Nrf2 and its target genes GST and NQO1, thereby inhibit cellular apoptosis. In animals, administration of 50 mg/kg body weight naringenin, for 45 days, significantly decreased STZ-induced blood glucose levels, normalized the lipid profile, and augmented the levels of antioxidants in pancreatic tissues. Immunohistochemical analysis measuring the number of insulin-positive cells in pancreas showed restoration of insulin expression similar to control animals. Furthermore, naringenin promoted glycolysis while inhibiting gluconeogenesis. In conclusion, naringenin could be a good anti-diabetic agent, which works by promoting Nrf2 levels and by decreasing cellular oxidative stress.

A Novel Dipeptidyl Peptidase IV Inhibitory Tea Peptide Improves Pancreatic β-Cell Function and Reduces α-Cell Proliferation in Streptozotocin-Induced Diabetic Mice

Dipeptidyl peptidase IV (DPP-IV) inhibitors occupy a growing place in the drugs used for the management of type 2 diabetes. Recently, food components, including food-derived bioactive peptides, have been suggested as sources of DPP-IV inhibitors without side effects. Chinese black tea is a traditional health beverage, and it was used for finding DPP-IV inhibitory peptides in this study. The ultra-filtrated fractions isolated from the aqueous extracts of black tea revealed DPP-IV inhibitory activity in vitro. Four peptides under 1 kDa were identified by SDS-PAGE and LC-MS/MS (Liquid Chromatography-Mass Spectrometry-Mass Spectrometry) from the ultra-filtrate. The peptide II (sequence: AGFAGDDAPR), with a molecular mass of 976 Da, showed the greatest DPP-IV inhibitory activity (in vitro) among the four peptides. After administration of peptide II (400 mg/day) for 57 days to streptozotocin (STZ)-induced hyperglycemic mice, the concentration of glucagon-like peptide-1 (GLP-1) in the blood increased from 9.85 ± 1.96 pmol/L to 19.22 ± 6.79 pmol/L, and the insulin level was increased 4.3-fold compared to that in STZ control mice. Immunohistochemistry revealed the improved function of pancreatic beta-cells and suppressed proliferation of pancreatic alpha-cells. This study provides new insight into the use of black tea as a potential resource of food-derived DPP-IV inhibitory peptides for the management of type 2 diabetes.

Anti-cataract Effect of Resveratrol in High-Glucose-Treated Streptozotocin-Induced Diabetic Rats

Resveratrol, which is a polyphenol found in grapes, peanuts, and other plants, has health benefits for various chronic diseases. The aim of the present study was to examine the effect of resveratrol on cataract formation in diabetic rats. Male Wistar rats (7-week-old) were treated with streptozotocin, and the streptozotocin-treated animals were administered 5% D-glucose in drinking water to promote the formation of cataracts by inducing severe hyperglycemia. Resveratrol supplementation (10 or 30 mg/kg/d) in drinking water was initiated immediately after induction of diabetes was confirmed. The full lens images of the horizontal plane were captured with the digital camera system which we developed. Cataract formation was assessed by an observer-based scoring method and by quantitative analysis of digital images of the lens. Cataracts at the peripheral region of the lens were detected 2 weeks after induction of hyperglycemia and progressed depending on the length of the diabetic period. The majority of them developed severe cataracts after 9 weeks of hyperglycemia. Resveratrol did not prevent the appearance of diabetic cataracts but significantly delayed the progression of cataracts compared with controls. The contents of sorbitol and protein carbonyls in lenses of diabetic rats were higher than those of control rats. Resveratrol suppressed the increase in protein carbonyls, but not of sorbitol, in diabetic lenses. These results suggest that resveratrol delays the progression of diabetic cataracts partially through attenuation of oxidative damage to lens proteins. Resveratrol may be beneficial in preventing the progression of diabetic cataracts.

Anti-inflammatory Effect of Juniperus Procera Extract in Rats Exposed to Streptozotocin Toxicity

BACKGROUND

Chronic inflammation is a critical health issue and implicated in several chronic health problems such as tumors, auto-immune disorder, hypertension or diabetes. However, Juniperus procera is one of the famous ancient plants that has been traditionally used to treat several diseases such as hyperglycemia, hepatitis, jaundice, bronchitis, and pneumonia.

OBJECTIVE

Current study is an attempt to investigate the anti-inflammatory effect of Juniperus procera extract on rats exposed to cytotoxicity caused experimentally by streptozotocin injections.

METHODS

Five groups of adult Wistar rats (10 rats each) were examined as (Normal control, Normal rats treated with Juniperus procera extract, rats administrated with streptozotocin, rats administrated with streptozotocin and treated with insulin and, rats administrated with streptozotocin and Juniperus procera extract). At the end of the experiment, blood was collected from experimented rats. Animals then were killed and small parts of both pancreas and liver were collected for gene expression and histopathological examination.

RESULTS

Serum analysis showed a significant increase in glucose, IL-6, IL-2 and TNF-α levels in rats exposed to streptozotocin. That change was reduced in rats cotreated with insulin or Juniperus procera extract. Moreover, streptozotocin showed a significant upregulation of IL-6, TNF-α and A2M genes, while, either insulin or Juniperus procera treatment was restored to normal status. Streptozotocin induced inflammation within hepatic tissues which clearly reduced in hepatic tissues of both insulin and junipers cotreated groups.

CONCLUSION

Streptozotocin toxicity induces acute inflammation and increases serum glucose, IL-6, IL-2 and TNF-α levels. However, Juniperus procera extract was found to significantly prevent that reaction within four weeks experimented frame time.

STREPTOZOTOCIN-INDUCED DIABETES MELLITUS - A PARADOX OF HIGH INTRINSIC PLATELET REACTIVITY AND LOW IN VITRO PLATELET AGGREGATION

CONTEXT

Studies of platelet function in diabetics are inconsistent, some studies reporting higher platelet reactivity, while others showed no change.

OBJECTIVE

We aimed to evaluate platelet indices and in vitro platelet aggregation in rats with long-lasting (28 weeks) diabetes mellitus.

DESIGN

Twelve controls and 14 diabetic rats were investigated. Diabetes was induced in 11-week-old rats using streptozotocin (60 mg/kg,i.p.). Platelet indices and in vitro adenosine diphosphate (ADP)-, protease-activated receptor 4 (PAR4) agonist-, and arachidonic acid (AA)-induced platelet aggregation were assessed at the age of 38 weeks.

RESULTS

Compared to controls, diabetic rats presented lower platelet count and plateletcrit (both p≤0.001), and higher mean platelet volume (p<0.01). ADP- (p=0.04) and AA-induced (p<0.01) platelet aggregation were lower in diabetic compared with control rats, whereas PAR4 agonist-induced platelet aggregation was similar between the two groups (p=1.00).

CONCLUSIONS

This study demonstrates a paradox of high intrinsic platelet reactivity and low in vitro ADP- and AA-induced platelet aggregation in diabetic rats compared with non-diabetic controls. The relevance of in vitro platelet aggregation to the contribution of platelets to in vivo thromboembolic events in diabetic rats remains questionable.

Nutritional content of selected species of tropical eggplant fruit (Solanum spp) diet Attenuates hepatic inflammation in high-fat fed male Wistar rats induced with streptozotocin

Tropical Solanum species contains a high level of phenolic acids and flavonoids, which were found to inhibit some key enzymes associated with the incidence of type 2 diabetes in in vitro and in vivo models based on earlier studies. This study was further designed to compare the nutritional properties, glycemic index, and hypolipidemic and the antioxidant effects of three species of tropical eggplant fruit (Solanum kumba, Solanum aethiopicum, and Solanum gilo) diet on streptozotocin (STZ)-induced nephrotoxicity in male Wistar rats. The animal model was subjected to high-fat diet prior to interperitional administration of streptozotocin (35 mg/kg wt); thereafter, the rats were given supplemented eggplant fruit diet, which lasted for 14 days. Determination of lipid content [triglycerides (TG), low-density lipoproteins (LDLs), high-density lipoproteins (HDLs), and total cholesterol (TC)], was assessed, while the liver biomarker enzymes alanine aminotransferase (ALT) alkaline phosphatase (ALP) and aspartate aminotransferase (AST), also endogenous enzymes such as superoxide dismutase (SOD) and catalase (CAT), were determined. Histopathological assessment of inflammation was carried out on kidney while the blood urea nitrogen (BUN), uric acid, and creatinine level on the kidney function were determined. The results showed that the groups with supplemented eggplant diet had significant (p < 0.05) reduction in lipid profile, decreased leakages of the liver, and kidney function enzymes while there was restoration of depleted endogenous antioxidant enzymes. The inflammatory cells and fat deposit from the histopathological view were reduced. However, S. kumba had the best nutritional output.

Diabetic neuropathy research: from mouse models to targets for treatment

Diabetic neuropathy is one of the most serious complications of diabetes, and its increase shows no sign of stopping. Furthermore, current clinical treatments do not yet approach the best effectiveness. Thus, the development of better strategies for treating diabetic neuropathy is an urgent matter. In this review, we first discuss the advantages and disadvantages of some major mouse models of diabetic neuropathy and then address the targets for mechanism-based treatment that have been studied. We also introduce our studies on each part. Using stem cells as a source of neurotrophic factors to target extrinsic factors of diabetic neuropathy, we found that they present a promising treatment.

Diabetes-induced Neuropathic Mechanical Hyperalgesia Depends on P2X4 Receptor Activation in Dorsal Root Ganglia

Peripheral diabetic neuropathy (PDN) manifests in 50-60% of type I and II diabetic patients and is the major cause of limb amputation. Adequate therapy for PDN is a current challenge. There are evidences that the activation of the P2X4 receptor (P2X4R) expressed on microglial cells of the central nervous system takes part in the development of neuropathic pain. However, there is an open question: Is P2X4R activation on dorsal root ganglia (DRG) involved in the development of neuropathic pain? To answer this question, this study verified the involvement of P2X4R expressed in DRG cells on diabetes-induced neuropathic mechanical hyperalgesia in rats. We found that intrathecal or ganglionar (L5-DRG) administration of a novel P2X4R antagonist (PSB-15417) or intrathecal administration of oligodeoxynucleotides (ODN)-antisense against the P2X4R reversed diabetes-induced neuropathic mechanical hyperalgesia. The DRG of the diabetic neuropathic rats showed an increase in P2X4R expression, and the DRG immunofluorescence suggested that P2X4R is expressed mainly in satellite glial cells (SGC). Finally, our study showed a functional expression of P2X4R in SGCs of the rat's DRG, because the P2X4R agonist BzATP elicits an increase in intracellular calcium concentration in SGCs, which was reduced by PSB-15417. These findings indicate that P2X4R activation in DRG is essential to diabetes-induced neuropathic mechanical hyperalgesia. Therefore, this purinergic receptor in DRG could be an interesting therapeutic target for quaternary P2X4R antagonists that do not cross the hematoencephalic barrier, for the control of neuropathic pain, preserving central nervous system functions.

Human chorionic gonadotropin decreases the phosphorylated tau protein level in streptozotocin-Alzheimeric male rats' hippocampus

INTRODUCTION

The pharmacological suppression of luteinising hormone or human chorionic gonadotropin (hCG) can reduce Aβ plaques in the brains of rats and mice, but the effects of hCG on the phosphorylated tau protein level in the hippocampus have not been studied. Therefore, we investigated the effects of hCG on the phosphorylated tau protein level and its effect on hCG receptor-immunoreactive neuron density in the hippocampus of Alzheimer's disease (AD) model rats (streptozotocin [STZ] injected intracerebroventricularly).

MATERIAL AND METHODS

The rats were administered hCG (50, 100, and 200 IU/200 µl saline, intraperitoneally) or vehicle once/day for three days after injection of STZ. The passive avoidance memory test was performed 6 hours after the last hCG injection. The phosphorylated tau protein level in the hippocampus was measured by ELISA, and hCG receptor-immunoreactive neurons were shown by immunohistochemical technique in areas of hippocampus.

RESULTS

Treatment with hCG attenuated memory deficiencies and reduced the level of phosphorylated tau protein in the hippocampus. hCG also improved the density of hCG receptor-immunoreactive neurons. The high dose of hCG hormone (200 IU/200 µl saline) seemed to have a significant effect on passive avoidance memory, phosphorylated tau protein concentration, and accumulation of hCG receptor-immunoreactive neurons in Alzheimeric rats' hippocampus.

CONCLUSIONS

In conclusion, hCG can provide protection against memory deficits induced by STZ and it can inhibit accumulation of tau hyperphosphorylation in the hippocampus. Furthermore, hCG can increase the hCG receptor-ir neurons number in the rats hippocampus after ICV injection of STZ.

Lisosan G Protects the Retina from Neurovascular Damage in Experimental Diabetic Retinopathy

Lisosan G (LG), a fermented powder obtained from whole grains, is a recognized antioxidant compound that improves the bioactivity and survival of different cell types. The purpose of this study was to investigate whether LG ameliorates both the neural and the vascular damage characterizing early stages of diabetic retinopathy (DR). The effects of LG were studied in cultured explants of mouse retinas challenged with oxidative stress (OS) or in retinas of streptozotocin (STZ)-treated rats. Apoptosis, vascular endothelial growth factor (VEGF) expression, OS markers, blood-retinal barrier (BRB) integrity, and inflammation were assessed, while retinal function was evaluated with electroretinogram (ERG). LG extensively inhibited apoptosis, VEGF expression, and OS both in retinal explants and in STZ rats. In addition, STZ rats treated with LG displayed an almost total BRB integrity, reduced levels of inflammatory markers and a partially restored visual function as evaluated with ERG. In summary, we demonstrated that LG exhibits antioxidant and anti-inflammatory effects that exert powerful protective actions against neural and vascular defects characteristic of DR. Therefore, LG-containing foods or supplements may be considered to implement DR treatments.

Administration of Momordica charantia Enhances the Neuroprotection and Reduces the Side Effects of LiCl in the Treatment of Alzheimer's Disease

Recently, the use of natural food supplements to reduce the side effects of chemical compounds used for the treatment of various diseases has become popular. Lithium chloride (LiCl) has some protective effects in neurological diseases, including Alzheimer’s disease (AD). However, its toxic effects on various systems and some relevant interactions with other drugs limit its broader use in clinical practice. In this study, we investigated the in vitro and in vivo pharmacological functions of LiCl combined with Momordica charantia (MC) in the treatment of AD. The in vitro results show that the order of the neuroprotective effect is MC5, MC3, MC2, and MC5523 under hyperglycemia or tau hyperphosphorylation. Therefore, MC5523 (80 mg/kg; oral gavage) and/or LiCl (141.3 mg/kg; intraperitoneal injection) were applied to ovariectomized (OVX) 3×Tg-AD female and C57BL/6J (B6) male mice that received intracerebroventricular injections of streptozotocin (icv-STZ, 3 mg/kg) for 28 days. We found that the combined treatment not only increased the survival rate by reducing hepatotoxicity but also increased neuroprotection associated with anti-gliosis in the icv-STZ OVX 3×Tg-AD mice. Furthermore, the cotreatment with MC5523 and LiCl prevented memory deficits associated with reduced neuronal loss, gliosis, oligomeric Aβ level, and tau hyperphosphorylation and increased the expression levels of synaptic-related protein and pS9-GSK3β (inactive form) in the icv-STZ B6 mice. Therefore, MC5523 combined with LiCl could be a potential strategy for the treatment of AD.

Growing pigs developed different types of diabetes induced by streptozotocin depending on their transcription factor 7-like 2 gene polymorphisms

The different polymorphisms of the transcription factor 7-like 2 (TCF7L2) gene promote variances in diabetes susceptibility in humans. We investigated whether these genotypes also promote differences in diabetic susceptibility in commercial pigs. Growing pigs (Landrace, both sex, 50-60 kg) with the C/C (n=4) and T/T (n=5) TCF7L2 genotypes were identified and intravenously injected with streptozotocin (STZ, 40 mg/kg) twice in weekly intervals, then a high-energy diet was offered. Oral glucose tolerance tests, blood analyses and the homeostasis model assessment-insulin resistance (HOMA-IR) index calculations were performed. The animals were sacrificed at the end of 12 weeks of treatment to reveal the pancreas histomorphometry. The results showed that all of the treated pigs grew normally despite exhibiting hyperglycemia at two weeks after the induction. The glycemic level of the fasting or postprandial pigs gradually returned to normal. The fasting insulin concentration was significantly decreased for the T/T carriers but not for the C/C carriers, and the resulting HOMA-IR index was significantly increased for the C/C genotype, indicating that the models of insulin dependence and resistance were respectively developed by T/T and C/C carriers. The histopathological results illustrated a significant reduction in the pancreas mass and insulin active sites, which suggested increased damage. The results obtained here could not be compared with previous studies because the TCF7L2 background has not been reported. Growing pigs may be an excellent model for diabetic in children if the animals are genetically pre-selected.

A comparison of metabolomic changes in type-1 diabetic C57BL/6N mice originating from different sources

Animal models have been used to elucidate the pathophysiology of varying diseases and to provide insight into potential targets for therapeutic intervention. Although alternatives to animal testing have been proposed to help overcome potential drawbacks related to animal experiments and avoid ethical issues, their use remains vital for the testing of new drug candidates and to identify the most effective strategies for therapeutic intervention. Particularly, the study of metabolic diseases requires the use of animal models to monitor whole-body physiology. In line with this, the National Institute of Food and Drug Safety Evaluation (NIFDS) in Korea has established their own animal strains to help evaluate both efficacy and safety during new drug development. The objective of this study was to characterize the response of C57BL/6NKorl mice from the NIFDS compared with that of other mice originating from the USA and Japan in a chemical-induced diabetic condition. Multiple low-dose treatments with streptozotocin were used to generate a type-1 diabetic animal model which is closely linked to the known clinical pathology of this disease. There were no significantly different responses observed between the varying streptozotocin-induced type-1 diabetic models tested in this study. When comparing control and diabetic mice, increases in liver weight and disturbances in serum amino acids levels of diabetic mice were most remarkable. Although the relationship between type-1 diabetes and BCAA has not been elucidated in this study, the results, which reveal a characteristic increase in diabetic mice of all origins are considered worthy of further study.

IL-33 Prevents MLD-STZ Induction of Diabetes and Attenuate Insulitis in Prediabetic NOD Mice

Type 1 diabetes is an autoimmune disease caused by the immune-mediated destruction of pancreatic β-cells. Prevention of type 1 diabetes requires early intervention in the autoimmune process against beta-cells of the pancreatic islets of Langerhans, which is believed to result from disordered immunoregulation. CD4+Foxp3+ regulatory T cells (Tregs) participate as one of the most important cell types in limiting the autoimmune process. The aim of this study was to investigate the effect of exogenous IL-33 in multiple low dose streptozotocin (MLD-STZ) induced diabetes and to delineate its role in the induction of protective Tregs in an autoimmune attack. C57BL/6 mice were treated i. p. with five doses of 40 mg/kg STZ and 0.4 μg rIL-33 four times, starting from day 0, 6, or 12 every second day from the day of disease induction. 16 weeks old NOD mice were treated with 6 injections of 0.4 μg/mouse IL-33 (every second day). Glycemia and glycosuria were measured and histological parameters in pancreatic islets were evaluated at the end of experiments. Cellular make up of the pancreatic lymph nodes and islets were evaluated by flow cytometry. IL-33 given simultaneously with the application of STZ completely prevented the development of hyperglycemia, glycosuria and profoundly attenuated mononuclear cell infiltration. IL-33 treatment was accompanied by higher number of IL-13 and IL-5 producing CD4+ T cells and increased presence of ST2+Foxp3+ regulatory T cells in pancreatic lymph nodes and islets. Elimination of Tregs abrogated protective effect of IL-33. We provide evidence that exogenous IL-33 completely prevents the development of T cell mediated inflammation in pancreatic islets and consecutive development of diabetes in C57BL/6 mice by facilitating the induction Treg cells. To extend this finding for possible relevance in spontaneous diabetes, we showed that IL-33 attenuate insulitis in prediabetic NOD mice.

Black Truffle Aqueous Extract Attenuates Oxidative Stress and Inflammation in STZ-Induced Hyperglycemic Rats via Nrf2 and NF-κB Pathways

Background and Purpose: Tuber melanosporum (black truffle) has been considered as a medicinal mushroom for a long time. T. melanosporum has the ability to attenuate oxidative stress and in turn diabetes mellitus (DM). DM has become an awfully common chronic unwellness, threatening people's well-being. There are nearly 1 in 10 people in the world affected by diabetes. Oxidative stress plays a crucial role in vascular complications related to DM. Our study aimed to attain an effective treatment method to alleviate oxidative stress by scavenging free radicals and reducing inflammation, to display how truffle aqueous extract (TE) attenuates hyperglycemia. Methods: Streptozotocin (STZ)-induced hyperglycemic rat model was accustomed to check the hypoglycemic effect of black truffle by relating it with Nrf2 and NF-κB pathways. Varied biomarkers and inflammatory markers were analyzed. Results: Rats treated with TE showed reduced glucose levels, attenuated oxidative stress through regulation of SOD, CAT, VIT-E, and VIT-C. The gene expression of Nrf2 and NF-κB in rats treated with TE was increased to normal group level. The mRNA expression of inflammatory pathway genes and oxidative stress pathway genes in rats treated with TE was brought back normal. Similar results were achieved in the rats treated with standard drug, glibenclamide (GB). TE conjointly inhibits the state of inflammation within the tissues generally littered with the symptoms of hyperglycemia. Conclusion: The results of our study show the hypoglycemic impact of black truffle on STZ-induced hyperglycemia in rats via Nrf2 and NF-κB pathways, and both pathways have significant improvement that may support the hypoglycemic impact of truffle.