Lutein dietary supplementation attenuates streptozotocin-induced testicular damage and oxidative stress in diabetic rats

Lutein Exerts Antioxidant and Neuroprotective Role on Schizophrenia-Like Behaviours in Mice

Schizophrenia is an esteemed neuropsychiatric condition delineated by the manifestation which role of the N-methyl-D-aspartate receptor (NMDAR) is important. Lutein administration exhibits protective effects via NMDA receptors. Thus, the main goal of this research was to investigate how lutein can possibly act as an antioxidant and provide protection for the brain against schizophrenia-like behaviours in mice. In total, 24 male mice were divided into four experimental groups: control, ketamine (20 mg/kg, i.p), lutein (10 mg/kg, i.p) and a mix of ketamine (20 mg/kg, i.p) and lutein (10 mg/kg, i.p). Lutein was given to the mice for 30 days, while ketamine was given from Days 16 to 30 to create a model of schizophrenia in the animals. After giving drugs, schizophrenia-like behaviours were evaluated with novel object recognition test (NORT), tail suspension test (TST), forced swimming test (FST) and open field tests. Furthermore, the amounts of brain malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) were assessed. The findings showed a noteworthy decrease in the crossings during the open field test and increase in immobility duration in the TST and FST as a result of ketamine administration (p < 0.05). Prior administration of lutein showed a decrease in the detrimental effects of ketamine on the open field assay, along with a reduction in immobility duration in the TST and FST experiments (p < 0.05). Administration of ketamine caused a notable reduction in the discrimination index, while pretreatment with lutein was associated with a rise in the discrimination index (p < 0.05). Furthermore, the administration of ketamine significantly increased the levels of MDA in both cortical and subcortical regions, which were then reduced by lutein pretreatment (p < 0.05). Moreover, ketamine use led to a significant decrease in tissue SOD, GPx and CAT levels in both cortical and subcortical brain regions in mice (p < 0.05). Nonetheless, lutein pretreatment significantly enhanced SOD, GPx and CAT levels in cortical and subcortical regions (p < 0.05). These results indicate that lutein may have protective effects on the brain to improve behavioural problems.

Environmental exposure to titanium dioxide nanoparticles disrupts DAZL gene expression and male reproductive function in mice: Protective role of lutein

Titanium dioxide nanoparticles (TiO2 NPs) are widely used nanomaterials with potential environmental health concerns, including impacts on male fertility. This study investigated the effects of TiO2 NPs on male reproductive function in mice and the potential protective role of lutein, a dietary antioxidant. Male NMRI mice were exposed to TiO2 NPs (50, 150, and 300 mg/kg) with or without co-administration of lutein (5 or 10 mg/kg) for 35 days. Compared to controls, TiO2 NP exposure significantly decreased DAZL gene expression, testosterone levels, antioxidant capacity, sperm quality (motility, density, morphology, DNA integrity), and testicular tissue parameters (seminiferous tubules volume, germinal epithelium height, spermatogenic cell counts). These effects were associated with increased oxidative stress markers (malondialdehyde levels) and altered testicular architecture (interstitial tissue volume). Notably, co-administration of lutein significantly ameliorated these TiO2 NP-induced adverse effects, suggesting its potential protective role against testicular oxidative stress and dysfunction. Our findings highlight the potential detrimental effects of environmental TiO2 NP exposure on male fertility and the potential benefit of dietary lutein as a protective strategy. Further research is needed to explore the underlying mechanisms and translate these findings to human health.

Lutein Production and Extraction from Microalgae: Recent Insights and Bioactive Potential

Microalgae have been reported to be excellent producers of bioactive molecules. Lutein is a pigment reported to have various beneficial effects for humans, and especially for eye well-being. In the current review, we summarize various methods that have been developed to optimize its extraction and bioactivities reported for human health. Several protective effects have been reported for lutein, including antioxidant, anticancer, anti-inflammatory, and cardioprotective activity. This review also reports attempts to increase lutein production by microalgae by changing culturing parameters or by using pilot-scale systems. Genetic engineering lutein production is also discussed. Considering the increasing aging of the worldwide population will create an increased need for lutein, a viable economic and eco-sustainable method to produce lutein is needed to face this market demand.

Oxidative stability of lutein on exposure to varied extrinsic factors

Pre-processing treatments performed on lutein sources can cause it to degrade, generating superfluous metabolites and lowering lutein's bioactivity. However, evidences suggesting extent of reduction in functional stability of lutein on exposure to such treatment conditions are nil. This study is first of its kind, where we attempted to gain clarity on the extent of degradation caused by the changes in temperature (40-100 °C), pH (2-8) and duration of such treatments. Increase (3.9 folds) in lutein loss within an hour at 40 °C occurred when pH was lowered from 8 to 2. Increase (1.7 folds) in lutein loss at neutral pH and 40 °C occurred when duration of exposure was increased from 1 to 4 h. Besides, lutein loss significantly increased on rising the temperature by every 10 °C. The functional stability of lutein in relation to its degradation was also studied by monitoring its radical scavenging activity. While lutein is highly unstable, lutein structure and its respective bioactivity can be significantly (p < 0.05) retained (< 12.44% and > 54.87% respectively) by maintaining the operating conditions at higher pH (7-8) and lower temperatures (40-50 °C) for a short period of time (< 1 h).

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05430-3.

Spermatogenesis and steroidogenesis disruption in a model of metabolic syndrome rats

CONTEXT

Metabolic syndrome (MetS) is a clustering of several physiological alterations.

OBJECTIVE

This study was designed to evaluate the effects of MetS on rats spermatogenesis and steroidogenesis.

MATERIALS AND METHODS

We developed a MetS rodent model using high-sugar and high-fat diet.

RESULTS

MetS rats showed severe disorders in sperm parameters. Interestingly, a significant increase in malondialdehyde level and a decrease in the antioxidant activities were observed. Moreover, qRT-PCR analysis showed Bax down-regulation and Bcl-2 up-regulation. A decrease in testosterone level was identified, correlated with the CYP11A1, CYP17A1 and 17β HSD testicular marker down-regulation. Finally, MetS rats showed an up-regulation of pro-inflammatory cytokines receptors IL-1R and IL-6R.

CONCLUSION

MetS induced severe testis toxicity in male rats. Mets markedly distorted sperm parameters, inhibited the transcription of steroidogenic enzymes and led to oxidative stress, inflammation, and alteration of Bax/Bcl-2 ratioin testicular tissues.

Lutein attenuated methylglyoxal-induced oxidative damage and apoptosis in PC12 cells via the PI3K/Akt signaling pathway

Methylglyoxal (MGO), a cytotoxic byproduct of glycolysis, causes neuro oxidative damage and apoptosis, and plays key roles in diabetic encephalopathy (DE). The goal of this research was to evaluate the roles of lutein attenuated MGO-induced damage in PC12 cells as well as the underlying mechanisms. The findings of this study showed that lutein has a significant impact on reducing the generation of reactive oxygen species (ROS) and oxidative stress in MGO-induced PC12 cells, which may be attributed to the increased antioxidant enzymes activity and the decreased MDA levels. Moreover, treatment with lutein also alleviated cell apoptosis and mitochondrial damage. Real-time PCR and western blot analysis showed that lutein enhanced the Bcl-2:Bax ratio, inhibited the expression of caspase-3 and caspase-9, and increased the protein level of phosphorylated Akt. The network pharmacology and molecular docking prediction results suggested that the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway was a potential mechanism of lutein in DE treatment. Furthermore, LY294002, a specific PI3K inhibitor, partially abolished the protective effect of lutein. These results presented that lutein attenuated oxidative damage and apoptosis triggered by MGO in PC12 cells via the PI3K/Akt signaling pathway. PRACTICAL APPLICATIONS: Lutein is a common carotenoid dispersed in fruits and vegetables. This article confirmed a protective effect of lutein on oxidative damage and apoptosis in PC12 cells after MGO damage. These results indicated that lutein could potentially be developed as a nutraceutical or functional food in the prevention of diabetic-related neurodegenerative diseases.

Effects of Creatine Supplementation on Histopathological and Biochemical Parameters in the Kidney and Pancreas of Streptozotocin-Induced Diabetic Rats

Diabetes mellitus (DM) is a worldwide health concern, and projections state that cases will reach 578 million by 2030. Adjuvant therapies that can help the standard treatment and mitigate DM effects are necessary, especially those using nutritional supplements to improve glycemic control. Previous studies suggest creatine supplementation as a possible adjuvant therapy for DM, but they lack the evaluation of potential morphological parameters alterations and tissue injury caused by this compound. The present study aimed to elucidate clinical, histomorphometric, and histopathological consequences and the cellular oxidative alterations of creatine supplementation in streptozotocin (STZ)-induced type 1 DM rats. We could estimate whether the findings are due to DM or the supplementation from a factorial experimental design. Although creatine supplementation attenuated some biochemical parameters, the morphological analyses of pancreatic and renal tissues made clear that the supplementation did not improve the STZ-induced DM1 injuries. Moreover, creatine-supplemented non-diabetic animals were diagnosed with pancreatitis and showed renal tubular necrosis. Therefore, even in the absence of clinical symptoms and unaltered biochemical parameters, creatine supplementation as adjuvant therapy for DM should be carefully evaluated.

Lutein as a Modulator of Oxidative Stress-Mediated Inflammatory Diseases

Lutein is a xanthophyll carotenoid obtained from various foods, such as dark green leafy vegetables and egg yolk. Lutein has antioxidant activity and scavenges reactive oxygen species such as singlet oxygen and lipid peroxy radicals. Oxidative stress activates inflammatory mediators, leading to the development of metabolic and inflammatory diseases. Thus, recent basic and clinical studies have investigated the anti-inflammatory effects of lutein based on its antioxidant activity and modulation of oxidant-sensitive inflammatory signaling pathways. Lutein suppresses activation of nuclear factor-kB and signal transducer and activator of transcription 3, and induction of inflammatory cytokines (interleukin-1β, interleukin-6, monocyte chemoattratant protein-1, tumor necrosis factor-α) and inflammatory enzymes (cyclooxygenase-2, inducible nitric oxide synthase). It also maintains the content of endogenous antioxidant (glutathione) and activates nuclear factor erythroid 2–related factor 2 (Nrf2) and Nrf2 signaling-related antioxidant enzymes (hemeoxygenase-1, NAD(P)H: quinone oxidoreductase 1, glutathione-s-transferase, glutathione peroxidase, superoxide dismutase, catalase). In this review, we have discussed the current knowledge regarding the anti-inflammatory function of lutein against inflammatory diseases in various organs, including neurodegenerative disorders, eye diseases, diabetic retinopathy, osteoporosis, cardiovascular diseases, skin diseases, liver injury, obesity, and colon diseases.

Induction of the antioxidant defense system using long-chain carotenoids extracted from extreme halophilic archaeon, Halovenus aranensis

The field of microbial pigments is an emerging area in natural products science. Carotenoids form a major class of such pigments and are found to be diversely synthesized by microorganisms that reside in hypersaline ecosystems to provide resistance against oxidative stress. Human cells can benefit from compounds such as carotenoids as antioxidant agents through either their capability to quench free radicals or their effect on promoting the antioxidant defense pathway. In this study, the antioxidant effectiveness of carotenoid extract from an extremely halophilic archaeon Halovenus aranensis strain EB27^T has been evaluated using different approaches. Finally, the ability of the extracted pigment to induce the antioxidant defense pathway of human primary skin fibroblast cells was studied. Hvn. aranensis carotenoid extract exhibited strong effectiveness such that at 2 µg/ml, the carotenoid extract fully neutralized the oxidative stress of hydrogen peroxide at its EC50 based on MTT assay. Results from real-time PCR of relevant genes, luciferase bioreporter of oxidative stress, and the western blot analysis further confirmed the antioxidant capability of the carotenoids. It was also shown the carotenoid extract had more antioxidant activity compared to β-carotene the same concentration. Results suggest the carotenoid extract from this archaeon to have high potential for clinical and industrial applications.

Genetic factors involved in modulating lutein bioavailability

Lutein exhibits effective antioxidant activity conferring protective action against oxidative stress in age-related macular degeneration and cognitive decline. The inability to synthesize these compounds by the human body and the necessity to combat day-to-day oxidative stress prioritizes daily consumption of lutein. However, the bioavailability of the orally consumed lutein largely depends on its gastrointestinal absorption and subsequent metabolism which is in turn governed by various intrinsic and extrinsic factors. One of the most important yet least studied factors is the genetic make-up of an individual. The proteins that partake in the absorption, transportation, metabolism and excretion of lutein are encoded by the genes that experience inter-individual variability. Reports suggest that the unanimous effect of phenotypes resulting from such inter-individual variability in the genes of interest causes modulation of lutein bioavailability which is discussed in detail in this review article. However, despite the available reports, a community-based approach to a larger population is required to obtain a stronger understanding of the relationship between inter-individual variability among these genes and lutein bioavailability. Such an understanding of nutrigenetics could not only pave a way to decipher mechanisms that modulate lutein bioavailability but also help in setting the dosage requirements of each patient.

Synergism of Dietary Co-Supplementation with Lutein and Bile Salts Improved the Growth Performance, Carotenoid Content, Antioxidant Capacity, Lipid Metabolism, and Lipase Activity of the Marbled Spinefoot Rabbitfish, Siganus rivulatus

A 60-day feeding trial was conducted to assess the effects of dietary supplementation with bile salts (BS), lutein (LTN), and their combination on growth, survival, carotenoid content, and antioxidant status of rabbitfish (Siganus rivulatus) larvae. Fish were fed four isonitrogenous (34.39% protein) and isoenergetic (20.57 kJ/g) diets supplemented with BS (0.15 g kg-1), LTN (0.1 g kg-1), BS+LTN (0.15 and 0.1 g kg-1, respectively), and a non-supplemented control diet. The results revealed that fish fed BS+LTN had the highest significant specific growth rate (4.37% day-1), feed efficiency (46.55%), and survival (97.78%). Lutein supplementation improved whole-body protein content, meanwhile, fish fed a BS-supplemented diet had a higher lipid content. The carotenoid deposition was significantly increased with LTN and BS+LTN in skin, muscle, and whole body compared to the control and BS treatment. All dietary supplementation of BS and LTN showed significant improvement in total antioxidant capacity, catalase, and glutathione peroxidase activities. Additionally, LTN alone or BS+LTN significantly reduced malondialdehyde levels by 5.30 and 29.91%, respectively compared to the control. BS supplementation modulated aminopeptidases activities, triglycerides, cholesterol, and increased the activity of pancreatic lipase. Therefore, it could be inferred that dietary supplementation with LTN in combination with BS could improve the growth performance, carotenoid deposition, antioxidant status, lipid digestion, and metabolism of S. rivulatus.

Loranthus micranthus nanoparticles abates streptozotocin-instigated testicular dysfunction in Wistar rats: Involvement of glucose metabolism enzymes, oxido-inflammatory stress, steroidogenic enzymes/protein and Nrf2 pathway

Loranthus micranthus (African mistletoe)-Loranthaceae family, is used in Nigerian traditional medicine for treating male infertility and lowering diabetic blood sugar levels. We investigated possible mechanism(s) involved in mitigation of L. micranthus leaves nanoparticles (LMLNPs) on streptozotocin (STZ)-induced testicular alterations. Type two diabetes mellitus (T2DM) was induced in male rats following 2 weeks feeding with fructose and single intraperitoneal injection of STZ. Control (nondiabetic) and (diabetic) rats received buffer only. Diabetic rats were treated with metformin or LMLNPs (two different doses) for 28 days. Hormonal profile, oxido-inflammatory stress parameters, glucose metabolism and steroidogenic enzymes/regulatory protein (StAR) and Nuclear factor erythroid 2-related factor 2 (Nrf2) protein in testes and sperm parameters were evaluated. Metformin and LMLNPs treatment significantly reduced blood glucose level in diabetic rats. Furthermore, LMLNPs enhanced glucose metabolism and testicular steroidogenic enzymes/protein, increased reproductive hormone levels and sperm functional parameters in diabetic rats. Additionally, LMLNPs suppressed testicular oxido-inflammatory stress biomarkers and inhibited lipid peroxidation in diabetic rats while augmenting Nrf2 pathway. Conclusively, LMLNPs potently reversed adverse effects of T2DM testicular dysfunction of rats. Use of LMLNPs in abating diabetic consequences proves an acceptable alternative to traditional crude extract preparations, as a result of better packaging and preservation.

Nutraceutical approach to enhance lutein bioavailability via nanodelivery systems

Lutein, a potent dietary carotenoid, has considerable biological activity and confers protection against age-related macular degeneration. Its bioavailability following consumption, however, depends on its rate of degradation. Nanodelivery systems with improved efficacy and stability are currently being developed to increase the bioavailability of lutein. This review examines nutraceutical approaches used in the development of such nanodelivery systems. It describes the methods of lutein preparation, the characteristics of various delivery systems, and the lutein delivery profile. In order to enhance lutein loading, provide electrostatic stabilization, and achieve the controlled release of lutein, adjuvants such as dextran moieties, whey proteins, medium-chain triglycerides, and chitosan polymers can be used to effectively reduce the particle size (&lt; 70 nm) and improve encapsulation efficiency (to 99.5%). The improved bioavailability of lutein via nanocrystals incorporated into rapidly dissolving films for oral consumption is a new area of exploratory research. This review aims to provide clarity about current research aimed at enhancing the bioavailability of lutein through the development of nanodelivery systems.

Trapa bispinosa Roxb. and lutein ameliorate cataract in type 1 diabetic rats

Trapa bispinosa Roxb. is an annual aquatic grass of the citrus family. Although its hot water extract displays antioxidative activity in vitro, little is known about its biological effectiveness. In the present study, we evaluated the extract’s inhibitory effect on diabetic cataractogenesis and formation of advanced glycation end-product. Lutein, which is beneficial for eye diseases, was administered concurrently. For short-term administration, Trapa bispinosa Roxb. hot water extract and/or lutein were administered to type 1 diabetic rats. N^ɛ-(carboxymethyl)lysine and N^ɛ-(carboxyethyl)lysine were quantified in serum using mass spectrometry. The long-term administration study was similar to the short-term, except that the dosages were lower. In the short-term study, co-administration of the extract and lutein inhibited N^ɛ-(carboxymethyl)lysine and N^ɛ-(carboxyethyl)lysine in serum. However, in the long-term study, only lutein inhibited N^ɛ-(carboxymethyl)lysine and N^ɛ-(carboxyethyl)lysine in serum. These results suggest that lutein exerts its long-term effect regardless of the concentration administered, while the extract exerts its effect when its concentration is increased. Relative to the consumption of the control diet, oral intake of the combination of the extract and lutein significantly inhibited the progression of cataractogenesis in the lens of diabetic rats, even at low doses, and the combination was more effective than individual treatments.

Protective effects of Salidroside on spermatogenesis in streptozotocin induced type-1 diabetic male mice by inhibiting oxidative stress mediated blood-testis barrier damage

Spermatogenic dysfunction is one of the major secondary complications of male diabetes. Salidroside (SAL) is the important active ingredients isolated from Herba Cistanche, which exhibits numerous pharmacological activities such as antioxidant, anti-diabetic, and anti-inflammatory effects. The present study was designed to determine whether SAL contributes to the recovery from spermatogenic dysfunction in streptozotocin (STZ) induced type-1 diabetic mice. SAL (25, 50, or 100 mg/kg) and Clomiphene citrate (CC, 5 mg/kg) were orally administered to male type-1 diabetic mice for 10 weeks. Testis tissues were collected for histopathological and biochemical analysis. Moreover, reproductive organ weight, sperm parameters, and testicular cell DNA damage were estimated. The results revealed that SAL significantly improved the weight of the reproductive organs, sperm parameters and testicular morphology to different degrees in type-1 diabetic mice. Furthermore, reactive oxygen species (ROS) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), markedly increased in the testicular tissue after SAL treatment. In addition, our data also showed a marked downregulation the fluorescence expressions of p38 MAPK phosphorylation and upregulation the protein expressions of ZO-1, Occludin, Claudin-11 and N-cadherin after SAL administration (100 mg/kg) compared with the type-1 diabetic group. In conclusion, these results demonstrated that SAL exerts protective effects on type-1 diabetes-induced male spermatogenic dysfunction, which is likely mediated by inhibiting oxidative stress-mediated blood testis barrier damage.

The Improvement Effects of Gordonia bronchialis on Male Fertility of Rats with Diabetes Mellitus Induced by Streptozotocin

Background: This study evaluated the possible protective effects of Gordonia bronchialis (Gb) on oxidative stress and some subsequent alterations on testis from rats undergoing an experimentally induced type 1 diabetes. Methods: A total of 40 male rats were randomly divided into four groups of ten. Diabetes was induced by injection of 55 mg/kg streptozotocin in 30 rats. Oral administration of Gb at dose of 105 (low dose) and 107 (high dose) CFU/rat was performed in two groups continuously for 14 days. The third and fourth groups received normal saline as the diabetic and healthy control groups, respectively. The blood and testicular tissue samples were taken on the 14th and 21st days post treatment for biochemical and histopathological evaluations. Results: Significant differences were found in blood glucose level, insulin, IL-6 and TNF-α values together with catalase and superoxide dismutase activities and malondialdehyde level in the diabetic group in comparison with healthy and Gb recipient groups. Moreover, the histopathological lesions observed in the diabetic rats mainly included basement membrane thickening, decreased number of Sertoli cells, and severe reduction of spermatogenesis markedly attenuated in Gb-treated rats. Conclusion: Taken together, it seems that oral administration of Gb could ameliorate testicular damage associated with some related parameters in the diabetic animal model.

Carbon Nanoparticles Inhibit Α-Glucosidase Activity and Induce a Hypoglycemic Effect in Diabetic Mice

New, improved therapies to reduce blood glucose are required for treating diabetes mellitus (DM). Here, we investigated the use of a new nanomaterial candidate for DM treatment, carbon nanoparticles (CNPs). CNPs were prepared by carbonization using a polysaccharide from Arctium lappa L. root as the carbon source. The chemical structure and morphology of the CNPs were characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and transmission electron microscopy. CNPs were spherical, 10-20 nm in size, consisting of C, H, O, and N, and featuring various functional groups, including C=O, C=C, C–O, and C–N. In vitro, the as-prepared CNPs could inhibit α-glucosidase with an IC₅₀ value of 0.5677 mg/mL, which is close to that of the reference drug acarbose. Moreover, in vivo hypoglycemic assays revealed that the CNPs significantly reduced fasting blood-glucose levels in mice with diabetes induced by high-fat diet and streptozocin, lowering blood glucose after intragastric administration for 42 days. To the best of our knowledge, this is the first report of CNPs exhibiting α-glucosidase inhibition and a hypoglycemic effect in diabetic mice. These findings suggest the therapeutic potential of CNPs for diabetes.

Polysaccharide from Okra (Abelmoschus esculentus (L.) Moench) Improves Antioxidant Capacity via PI3K/AKT Pathways and Nrf2 Translocation in a Type 2 Diabetes Model

Polysaccharide extracted from okra (Abelmoschus esculentus (L.) Moench), a traditional functional food, is a biologically active substance reported to possess hypoglycemic and anti-oxidative qualities. However, it is unknown which polysaccharides play a role and have the potential mechanism. This present study is to assess the possible impacts of a novel polysaccharide isolated from okra (OP) on mice fed with a high-fat diet (HFD) combined with an intraperitoneal injection (i.p.) of 100 mg/kg streptozotocin (STZ) twice, to induce type 2 diabetes mellitus (T2DM). We found that an eight-week administration of OP at 200 or 400 mg/kg body weight significantly alleviated the symptoms, with elevations in blood glucose, triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), as well as reducing high-density lipoprotein cholesterol (HDL-C), body weight, food, and water consumption. The OP treatment increased the hepatic glycogen and decreased the mussy hepatic cords and liver fibrosis in the T2DM mice. The decreases of ROS and MDA and the increases of SOD, GSH-Px and CAT in liver were observed after administration of OP. OP alleviated the T2DM characteristics through the activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3 beta (GSK3β) pathway, and enhanced the nuclear factor erythroid-2 (Nrf2) expression and promoted Nrf2-medicated heme oxygenase-1(HO-1) and superoxide dismutase 2 (SOD2) expression. OP also relieved mitochondrial dysfunction by inhibiting NOX2 activation. Taken together, these findings suggest that a polysaccharide isolated from okra exerts anti-T2DM effects partly by modulating oxidative stress through PI3K/AKT/GSK3β pathway-medicated Nrf2 transport. We have determined that a polysaccharide possesses hypoglycemic activity, as well as its underlying mechanism.

Erectile dysfunction attenuation by naringenin in streptozotocin-induced diabetic rats

Diabetes mellitus is associated with sexual dysfunction, which leads to infertility in animal models. The aim of this study was to evaluate sexual behavior in diabetic rats administered with naringenin. Rats were classified into five groups including healthy controls, those with STZ-induced diabetes, and those with STZ-induced diabetes then treated with 25, 50, or 100 mg kg^-1  day^-1 of naringenin. Male rats were introduced to sexually receptive females, and data were collected regarding sexual behavior and erectile activity. Blood samples were taken and histopathological analyses were carried out. ANOVA and the Student-Newman-Keuls t test were used for statistical comparisons. Sexual behavioral, mount latency, intromission latency, ejaculation latency, and postejaculatory interval were significantly increased in diabetic rates compared with controls (p < 0.001). The NG-treated rats showed a significant improvement in testosterone and cyclic guanosine monophosphate levels, and testicular oxidative stress and inflammatory biomarkers were corrected in a dose-dependent manner compared with controls. The treatment protocol used in this study led to the elimination of sexual impairment resulting from DM, and naringenin showed significant antiinflammatory and antioxidant effects in testicular cells. PRACTICAL APPLICATIONS: Erectile dysfunction occurs in more than 50% of men who are diagnosed with diabetes mellitus. The prevalence of ED is 25% in patients younger than 50 years and 75% in those older than 50 years. Chronic DM leads to oxidative stress, which has significant effects on sexual behavior, spermatogenesis, and sperm biology. Phenolic compounds have been reported to reduce streptozotocin-induced oxidative stress in experimental animal models. In addition, they have significant effects on the generation of sperm (spermatogenesis), which is involved in the pathogenesis of chronic DM. Our study was designed to examine the effect of naringenin, a flavone flavonoid, on oxidative stress, the inflammatory process, sexual behavior, erectile activity through spermatogenesis, and cavernous cyclic guanosine monophosphate in streptozotocin-induced diabetic rats.

Vitamin D3 Activates Phosphatidylinositol-3-Kinase/Protein Kinase B via Insulin-Like Growth Factor-1 to Improve Testicular Function in Diabetic Rats

OBJECTIVE

In diabetes mellitus, vitamin D₃ deficiency affects sex hormone levels and male fertility; however, the mechanism leading to the disorder is unclear. This research was designed to investigate the mechanism of vitamin D₃ deficiency and hypogonadism in diabetic rats. Our aim was to assess serum vitamin D₃ levels and the relationship among vitamin D₃, insulin-like growth factor-1 (IGF-1), and testicular function.

MATERIALS AND METHODS

Rats with streptozotocin-induced diabetes were randomly divided into four groups and treated with different doses of vitamin D₃: no vitamin D₃, low (0.025 μg/kg/day), high (0.1 μg/kg/day), and high (0.1 μg/kg/day) with JB-1 (the insulin-like growth factor-1 receptor inhibitor group, 100 μg/kg/day). The groups were compared with wild-type rats, which function as the control group. Various parameters such as vitamin D₃ and IGF-1 were compared between the experimental and wild-type groups, and their correlations were determined.

RESULTS

Twelve weeks of vitamin D₃ supplementation improved the testosterone levels, as shown by the increase in the level of serum IGF-1 in diabetic rats. Phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT), which was a downstream of the signaling pathway of IGF-1, was significantly increased after vitamin D₃ treatment.

CONCLUSIONS

The study shows that vitamin D₃ may promote the expression of testosterone and improve testicular function in diabetic rats by activating PI3K/AKT via IGF-1.

Proinsulin C-peptide as an alternative or combined treatment with insulin for management of testicular dysfunction and fertility impairments in streptozotocin-induced type 1 diabetic male rats

Diabetes mellitus (DM) is closely associated with male infertility and sexual dysfunction. Recent data indicate that the proinsulin C-peptide (CP) exerts important physiological effects and shows the characteristics of an endogenous peptide hormone. So, this study was done to investigate the effect of C-peptide with or without insulin treatment on testicular function and architecture in diabetic rats. Rats were divided into the following groups: control, diabetic, and diabetic groups treated with either CP alone or combined with insulin. Tested parameters included, estimation of serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and glucose levels, testicular samples for histopathology and estimation of malondialdehyde (MDA), total antioxidant capacity (TAC), and B-cell leukemia/lymphoma-2 (BCL-2) levels as well as sperm count and motility. Results showed that DM caused a severe alteration in hormonal profile and reduced sperm parameters along with increased MDA and decrease in both TAC and BCL-2 levels. CP alone or with insulin treatment efficiently reversed all the negative effects of DM on rat testes, with maximum improvement in the combined regimen. Proposed mechanisms may involve its hypoglycemic, antioxidant, and antiapoptotic properties. Thus, CP could substitute for or better combined with insulin to prevent or retard diabetic-induced testicular dysfunction.

Antioxidant, anti-inflammatory, and anti-apoptotic effects of zinc supplementation in testes of rats with experimentally induced diabetes

One of the major obstacles that males with diabetes may confront is subfertility or infertility. Thus, the present study investigated the effect of co-administration of metformin and zinc (Zn) on the testes of streptozotocin-induced diabetic rats. Male albino rats were randomly divided into 4 groups: control group; untreated diabetic group; diabetic + metformin group, in which diabetic rats were treated orally with metformin (250 mg/kg) once daily for 4 weeks; and diabetic + metformin + Zn group, in which diabetic rats were treated orally with metformin in combination with Zn (10 mg/kg) once daily for 4 weeks. Concomitant administration of metformin and Zn produced a significant decrease in serum levels of glucose and insulin and testicular levels of malondialdehyde and tumor necrosis factor α. Additionally, there was a significant increase in serum levels of Zn, testosterone, and follicle-stimulating hormone, as well as testicular total antioxidant capacity and anti-apoptotic protein Bcl-2, when compared with both the diabetic and metformin-treated diabetic groups. Moreover, co-administration of Zn and metformin significantly improved testicular histopathology, with a significant reduction in percent area of collagen fibers and nuclear factor kappa B (p65) immunoreactivity and a significant increase in seminiferous tubule diameter and connexin 43 immunoreactivity as compared with the diabetic and metformin-treated diabetic groups. In conclusion, the combination of Zn and metformin was an efficacious and safe alternative treatment, as it had superior antihyperglycemic efficacy and provided additional benefits over metformin alone in rats with type 2 diabetes.

Amelioration effects of nanoencapsulated triterpenoids from petri dish-cultured Antrodia cinnamomea on reproductive function of diabetic male rats

PURPOSE

Nanoencapsulated triterpenoids from petri dish-cultured Antrodia cinnamomea (PAC) and its amelioration effects on reproductive function in diabetic rats were investigated.

MATERIALS AND METHODS

PAC encapsulated in silica-chitosan nanoparticles (Nano-PAC) was prepared by the biosilicification method. The diabetic condition in male Sprague Dawley rats was induced by high-fat diet and streptozotocin (STZ). Three different doses of Nano-PAC (4, 8, and 20 mg/kg) were administered for 6 weeks. Metformin and control of nanoparticles (Nano-con) were taken as positive and negative controls, respectively.

RESULTS

The average particle size was ~79.46±1.63 nm, and encapsulation efficiency was ~73.35%±0.09%. Nano-PAC administration improved hyperglycemia and insulin resistance. In addition, Nano-PAC ameliorated the morphology of testicular seminiferous tubules, sperm morphology, motility, ROS production, and mitochondrial membrane potential. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) antioxidant, as well as testosterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) were increased, whereas proinflammatory cytokines TNF-α, IL-6, and IFN-γ were decreased.

CONCLUSION

In the present study, we successfully nanoencapsulated PAC and found that a very low dosage of Nano-PAC exhibited amelioration effects on the reproductive function of diabetic rats.

Hypoglycemic, hypolipidemic and antioxidant effects of iridoid glycosides extracted from Corni fructus: possible involvement of the PI3K-Akt/PKB signaling pathway

Iridoid glycosides (CIG) are the major component of Corni fructus. In this work, we researched the antioxidative, hypoglycemic and lowering blood lipids effects of CIG on diabetic mice induced by a high-fat diet (HFD) and streptozotocin (STZ). Furthermore, to investigate the molecular mechanism of action, the phosphorylation and protein expression of phosphoinositide 3-kinase (PI3K) and its downstream proteins, such as insulin receptor (INSR), protein kinase B (Akt/PKB) and glucose transporter 4 (GLUT4) have been detected. The results showed that CIG significantly improved oral glucose tolerance in diabetic mice. Biochemical indices also revealed that CIG had a positive effect on lipid metabolism and oxidative stress. In addition, CIG can significantly enhance the expression level of the PI3K-Akt/PKB pathway related proteins in skeletal muscle, which is the key pathway of insulin metabolism. These findings show that CIG can improve the hyperglycemia and hyperlipidemia of HFD-STZ-induced diabetic mice through the PI3K-Akt/PKB signaling pathway, and CIG might be a potential medicine or functional food for type 2 diabetes mellitus remedies.

Influence of hyperglycemia on liver inflammatory conditions in the early phase of non-alcoholic fatty liver disease in mice

OBJECTIVES

A non-alcoholic fatty liver disease (NAFLD) has high prevalence and now important issue of public health. In general, there exists strong interaction between NAFLD and diabetes, but the detailed mechanism is unclear. In this study, we determined the effects of hyperglycemia on progression in the early phase of NAFLD in mice.

METHODS

Male ddY mice were fed a choline-deficient, l-amino acid-defined, high-fat diet (CDAHFD) consisting of 60% of kcal from fat and 0.1% methionine by weight. Hyperglycemic condition was induced by streptozotocin (STZ) treatment. The assessment of liver function used serum AST and ALT levels, and histological analysis. Hepatic tumour necrosis factor (TNF)-α mRNA levels was estimated by qRT-PCR.

KEY FINDINGS

During the 3-42 days that the mice were fed CDAHFD, the livers gradually caused accumulation of fat, and infiltration of inflammation cells gradually increased. Serum AST and ALT levels and significantly increased after being fed CDAHFD for 3 days and were exacerbated by the STZ-induced hyperglycemic condition. In addition, hepatic TNF-α mRNA also significantly increased. These phenomena reversed by insulin administration.

CONCLUSIONS

The results showed that progression in the early phase of NAFLD may be exacerbated by hyperglycemia-induced exacerbation of inflammation.

HGF/C-MET PATHWAY HAS A ROLE IN TESTICULAR DAMAGE IN DIABETES INDUCED BY STREPTOZOTOCIN

Objective

The aim of the study was to investigate the role of Hepatocyte Growth Factor (HGF)/c-Met pathway in testicular damage provoked by streptozotocin (STZ)- induced diabetes and the effects of insulin treatment on the HGF/c-Met pathway.

Methods

Total 21 paraffin-embedded testicular tissues of control (n=7), streptozotocin (STZ)-induced diabetic (n=7) and insulin-treated diabetic (n=7) Wistar albino rats were used in this study. Testicular damage was examined histologically and by Johnsen's score was also evaluated. Immunohistochemical stainings of HGF and c-Met were analysed by using antibodies against HGF and c-Met.

Results

We found the degeneration in seminiferous tubule epithelium and disorganization of spermatogenetic cell series in testis tissues of diabetic rats. We also determined decrease both in seminiferous tubule diameter and Johnsen's scores in diabetic group. The expressions of HGF and c-Met in seminiferous tubule epithelium and in spermatogenic cells (especially spermatocytes and spermatids) were significantly increased in diabetic rats compared to those of control. Insulin treatment significantly reduced the diabetes-induced morphological changes and HGF/c-Met over expressions in the diabetic rat testis.

Conclusion

HGF/c-Met pathway might have a role in diabetes- induced testicular damage. Drugs acting on this pathway might be effective to prevent or delay the testicular damage induced by diabetes.

Iridoid glycoside from Cornus officinalis ameliorated diabetes mellitus-induced testicular damage in male rats: Involvement of suppression of the AGEs/RAGE/p38 MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (CO) has been widely used as a traditional Chinese medicine for treating diabetes mellitus (DM) and its complications. Iridoid glycoside from C. officinalis (IGCO) can resist apoptosis, hyperglycemia, oxidation and so on. The aim of this study was to investigate the therapeutic effects of IGCO on DM-induced testicular damage through inhibition of the AGEs/RAGE/p38 MAPK signaling pathway.

MATERIALS AND METHODS

A DM model of male Wistar rats was induced with streptozotocin injection (30mg/kg, i.p.) and high-fat diet. The DM rats were administrated with IGCO at low and high doses (15 and 30mg/kg, p.o.) for 12 weeks. Testicular damage was evaluated by estimating relative testicular weights, testicular pathohistology, sperm count, live sperm rate, endogenous sex hormone level and activity of testicular marker enzymes. Besides, general diabetic symptoms, renal function, oxidative stress parameters and testicular apoptosis marker were also determined. Finally, the mechanism was explored based on the AGEs/RAGE/p38 MAPK pathway.

RESULTS

IGCO effectively mitigated the general symptoms of DM rats including weight loss, polydipsia, polyphagia, polyuria, elevated blood glucose level and low serum insulin level. Nourishing the kidney evidently, IGCO reduced serum creatinine, urea nitrogen and urine protein excretion, and also markedly protected against DM-induced testicular damage by increasing testis/body weight ratio and live sperm rate, improving the histomorphology of testes, upregulating testosterone, LH, FSH and GnRH levels and preventing the decrease of testicular marker enzymes LDH, ACP and γ-GT. Moreover, IGCO showed considerable anti-oxidative and anti-apoptotic effects, which downregulated the increase of ROS and MDA levels, restored SOD and CAT activities, and decreased spermatogenic cell apoptosis and Bax/Bcl-2 ratio. In the end, the increased AGEs, RAGE and p-p38 MAPK protein levels in DM rats were also reversed by IGCO significantly.

CONCLUSIONS

The kidney tonic IGCO well protected DM rats from testicular damage, which may be related to suppression of the AGEs-RAGE-p38 MAPK pathway.

Azuki bean (Vigna angularis) extract reduces oxidative stress and stimulates autophagy in the kidneys of streptozotocin-induced early diabetic rats

Diabetic kidney disease is associated with oxidative stress, inflammation, and autophagy. The aim of this study was to investigate the effect of azuki bean (Vigna angularis) extract (ABE) on oxidative stress and autophagy in the kidneys of diabetic rats. Streptozotocin (STZ)-induced diabetic rats received 0, 10, or 40 mg/kg of ABE orally for 4 weeks, whereas vehicle-injected control rats received distilled water. Level of plasma glutathione and expression of heme oxygenase-1 (HO-1), p47phox (NADPH oxidase subunit), and markers associated with autophagy were examined. The glutathione level in the 40 mg/kg ABE-treated diabetic group (ABE-40 group) was higher than that of the untreated diabetic group (ABE-0 group). The HO-1 and p47phox protein expression levels of the ABE-40 group were lower (47% and 33%, respectively) than those of the ABE-0 group. The level of light chain 3B II (LC3B-II) was higher in the ABE-40 group than in the ABE-0 group. Protein levels of p62/sequestosome 1 (p62) in the ABE-40 group were lower than those in the ABE-0 group. Our results suggest that ABE may attenuate STZ-induced diabetic kidney injury by suppressing oxidative stress and (or) by upregulating autophagy.

Selenium Nanoparticles Attenuate Oxidative Stress and Testicular Damage in Streptozotocin-Induced Diabetic Rats

We investigated the protective and antioxidative effects of selenium nanoparticles (SeNPs) in streptozotocin STZ-induced diabetic rats. STZ-diabetic rats were exposed daily to treatments with SeNPs and/or insulin and then the effect of these treatments on the parameters correlated to oxidative damage of the rat testes were assessed. Biochemical analysis revealed that SeNPs are able to ameliorate the reduction in the serum testosterone caused by STZ-induced diabetes. Furthermore, SeNPs could significantly decrease testicular tissue oxidative stress markers, namely lipid peroxidation and nitric oxide. In contrast, treatment of the STZ-diabetic rats with SeNPs increased the glutathione content and antioxidant enzyme activities in testicular tissues. Moreover, microscopic analysis proved that SeNPs are able to prevent histological damage in the testes of STZ-diabetic rats. Molecular analysis revealed that the mRNA level of Bcl-2 (B-cell lymphoma 2) is significantly upregulated. On the contrary, the mRNA level of Bax (Bcl-2 Associated X Protein) was significantly downregulated. Furthermore, treatment of STZ-diabetic rats with SeNPs led to an elevation in the expression of PCNA (Proliferating Cell Nuclear Antigen Gene). Interestingly, the insulin treatment also exhibited a significant improvement in the testicular function in STZ-diabetic rats. Collectively, our results demonstrated the possible effects of SeNPs in attenuating diabetes-induced oxidative damage, in particular in testicular tissue.