Protective effects of vitamins (C and E) and melatonin co-administration on hematological and hepatic functions and oxidative stress in alloxan-induced diabetic rats

Aging-Related Ovarian Failure and Infertility: Melatonin to the Rescue

Aging has a major detrimental effect on the optimal function of the ovary with changes in this organ preceding the age-related deterioration in other tissues, with the middle-aged shutdown leading to infertility. Reduced fertility and consequent inability to conceive by women in present-day societies who choose to have children later in life leads to increased frustration. Melatonin is known to have anti-aging properties related to its antioxidant and anti-inflammatory actions. Its higher follicular fluid levels relative to blood concentrations and its likely synthesis in the oocyte, granulosa, and luteal cells suggest that it is optimally positioned to interfere with age-associated deterioration of the ovary. Additionally, the end of the female reproductive span coincides with a significant reduction in endogenous melatonin levels. Thus, the aims are to review the literature indicating melatonin production in mitochondria of oocytes, granulosa cells, and luteal cells, identify the multiple processes underlying changes in the ovary, especially late in the cessation of the reproductive life span, summarize the physiological and molecular actions of melatonin in the maintenance of normal ovaries and in the aging ovaries, and integrate the acquired information into an explanation for considering melatonin in the treatment of age-related infertility. Use of supplemental melatonin may help preserve fertility later in life and alleviate frustration in women delaying childbearing age, reduce the necessity of in vitro fertilization–embryo transfer (IVF-ET) procedures, and help solve the progressively increasing problem of non-aging-related infertility in women throughout their reproductive life span. While additional research is needed to fully understand the effects of melatonin supplementation on potentially enhancing fertility, studies published to date suggest it may be a promising option for those struggling with infertility.

Modeling type 2 diabetes in rats by administering tacrolimus

The prevalence of diabetes is rapidly increasing. The current number of diagnosed cases is ~422 million, expected to reach ~640 million by 2040. Type 2 diabetes, which constitutes ~95% of the cases, is characterized by insulin resistance and a progressive loss of β-cell function. Despite intense research efforts, no treatments are yet able to cure the disease or halt its progression. Since all existing animal models of type 2 diabetes have serious drawbacks, one is needed that represents the complete pathogenesis, is low cost and non-obese, and can be developed relatively quickly. The aim of this study was to evaluate a low-cost, non-obese model of type 2 diabetes engendered by administering a daily high dose of tacrolimus (an immunosuppressant) to Wistar rats for 4 weeks. The biochemical and antioxidant markers were measured at basal and after the 4-week tacrolimus treatment. At week 4, the values of these parameters closely resembled those observed in human type 2 diabetes, including fasting blood glucose at 141.5 mg/dL, blood glucose greater than 200 mg/dL at 120 min of the glucose tolerance test, blood glucose at varied levels in the insulin tolerance test, and elevated levels of cholesterol and triglyceride. The tacrolimus treatment produced hypoinsulinemia and sustained hyperglycemia, probably explained by the alteration found in pancreatic β-cell function and morphology. This model should certainly be instrumental for evaluating possible type 2 diabetes treatments, and for designing new immunosuppressants that do not cause pancreatic damage, type 2 diabetes, or new-onset diabetes after transplantation (NODAT).

The effects of caffeic acid phenethyl ester on retina in a diabetic rat model

PURPOSE

We aimed to investigate the effect of caffeic acid phenethyl ester (CAPE) on retinal apoptosis and oxidative stress parameters in streptozotocin (STZ) induced diabetic rat model.

METHODS

This study included 3 groups; control, STZ, and STZ + CAPE. The rats in STZ, and STZ + CAPE groups were injected with STZ (35 mg/kg, i.p.) for induction of diabetes. In the STZ + CAPE group, 10 µmol/kg of CAPE were intraperitoneally injected for 4 weeks. Control and STZ groups were given only intraperitoneal vehicle (saline). Rats were anaesthetized and sacrificed on the 4th week of the experiment. Total anti-oxidant status (TAS), and total oxidant status (TOS) were measured on the dissected retinal tissues. Oxidative stress index (OSI) was also calculated. Fellow eyes were used for histopathologic evaluation with caspase-3 and matrix metalloproteinase-2 (MMP-2) and MMP-9 evaluation.

RESULTS

TAS levels were similar between groups (p = 0.71). However, CAPE treatment prevented the elevation of the TOS in the STZ + CAPE group compared to the STZ group (30.93 ± 9.97 vs 61.53 ± 24.7 nmol H₂O₂ Eq/mg protein, p = 0.007). OSI was also significantly lower in the STZ + CAPE group than that of the STZ group (20.01 ± 5.87 vs. 37.90 ± 14.32, respectively, p = 0.007). Retinal caspase-3 staining, MMP-2 and MMP-9 scores were not different between groups (p > 0.05 for all).

CONCLUSION

The present study demonstrated that CAPE treatment may decrease the oxidative stress in the retina in STZ induced diabetic rat model. However, apoptosis was not observed in the retina. The retinal apoptosis cannot be shown probably due to a shorter period of diabetes.

Efficacy of melatonin in restoring the antioxidant status in the lens of diabetic rats induced by streptozotocin

Background

Melatonin is a well-known free radical scavenger. The present study aimed to investigate the effects of melatonin treatment on the antioxidant status in the lenticular tissue of streptozotocin (STZ)-induced diabetic rats.

Methods

Thirty-four male rats were randomly divided into four groups as follows: healthy control rats (group 1, n = 10); diabetic control rats (group 2, n = 10); melatonin-treated (5 mg/kg·day) diabetic rats (group 3, n = 10) and melatonin-treated (5 mg/kg·day) healthy rats (group 4, n = 4). Diabetes was induced by injection of streptozotocin (50 mg/kg, ip). Following 8-weeks of melatonin treatment, all rats were killed and the blood plasma and their lenses were stored at -70 °C for antioxidant enzyme activities assay and biochemical determination.

Results

The plasma glucose and lens malondialdehyde (MDA) increased significantly in the rats of group 2 as compared to the group 1. Also, a significant decrease in the levels of catalase (CAT) and glutathione reductase (GR) activities in the lenses and plasma reduced glutathione (GSH) was found. However, the levels of lenticular MDA (not significant) and the plasma glucose significantly decreased in the rats of group 3 compared to the group 2. Besides, the levels of CAT, GR in the rats lens and plasma GSH increased significantly.

Conclusion

Diabetes mellitus induced hyperglycemia and oxidative stress, whereas melatonin decreased the blood glucose levels and lipid peroxidation and increased the activities of antioxidant enzymes in diabetic rat lenses.

Agomelatine pretreatment prevents development of hyperglycemia and hypoinsulinemia in streptozotocin-induced diabetes in mice

The main objective of this study was to investigate potential effectiveness of agomelatine pretreatment in the prevention of diabetes itself and encephalopathy, with a focus on brain tissue oxidative stress and inflammatory processes in streptozotocin (STZ)-induced diabetic mice. Interleukine-1β (IL-1β) and TACR1 (NK1), which is a tachykinine receptor, were used for the investigation of inflammation in the brain regions including raphe nucleus, periaqueductal gyrus (PAG), amygdala, and nucleus accumbens. The effects of agomelatine on total antioxidant capacity were also evaluated. In the in vitro part of the study, the effects of agomelatine on cell viability were investigated in dorsal root ganglion (DRG) neurons. Fasting blood glucose levels were measured 72 h after STZ injection to determine the diabetic condition. Agomelatine pretreatment prevented both hyperglycemia and hypoinsulinemia in STZ-treated mice. When STZ was injected to induce diabetes in mice, neither hyperglycemia nor hypoinsulinemia was developed in agomelatine pretreated mice and 6 weeks after development of diabetes, agomelatine treatment significantly decreased levels of IL-1β mRNA in raphe nucleus and nucleus accumbens. TACR1 mRNA levels were lower in raphe nucleus, PAG, and amygdala of agomelatine-treated diabetic mice. The increase in total antioxidant capacity after agomelatine administration may responsible for its beneficial effect in the prevention of diabetes. We showed that agomelatine reversed high glucose-induced cell viability decreases in DRG neurons. Both the antihyperglycemic and antioxidant effects of agomelatine might have contributed to the DRG neuron viability improvement. In conclusion, agomelatine seems to both prevent development of diabetes and reverse the encephalopathic changes caused by diabetes.

Melatonin resists oxidative stress-induced apoptosis in nucleus pulposus cells

AIMS

Intervertebral disc degeneration (IVDD) is thought to be the major cause of low back pain (LBP), which is still in lack of effective etiological treatment. Oxidative stress has been demonstrated to participate in the impairment of nucleus pulposus cells (NPCs). As the most important neuroendocrine hormone in biological clock regulation, melatonin (MLT) is also featured by good antioxidant effect. In this study, we investigated the effect and mechanisms of melatonin on oxidative stress-induced damage in rat NPCs.

MAIN METHODS

Cytotoxicity of H₂O₂ and protecting effect of melatonin were analyzed with Cell Counting kit-8 (CCK-8). Cell apoptosis rate was detected by Annexin V-FITC/PI staining. DCFH-DA probe was used for the reactive oxygen species (ROS) detection. The mitochondrial membrane potential (MMP) changes were analyzed with JC-1 probe. Intracellular oxidation product and reductants were measured through enzymatic reactions. Extracellular matrix (ECM) and apoptosis associated proteins were analyzed with Western blot assays.

KEY FINDINGS

Melatonin preserved cell viability of NPCs under oxidative stress. The apoptosis rate, ROS level and malonaldehyde (MDA) declined with melatonin. MLT/H₂O₂ group showed higher activities of GSH and SOD. The fall of MMP receded and the expression of ECM protein increased with treatment of melatonin. The mitochondrial pathway of apoptosis was inhibited by melatonin.

SIGNIFICANCE

Melatonin alleviated the oxidative stress-induced apoptosis of NPCs. Melatonin could be a promising alternative in treatment of IVDD.

Effects of Melatonin on Glucose Homeostasis, Antioxidant Ability, and Adipokine Secretion in ICR Mice with NA/STZ-Induced Hyperglycemia

Diabetes is often associated with decreased melatonin level. The aim was to investigate the effects of different dosage of melatonin on glucose hemostasis, antioxidant ability and adipokines secretion in diabetic institute for cancer research (ICR) mice. Forty animals were randomly divided into five groups including control (C), diabetic (D), low-dosage (L), medium-dosage (M), and high-dosage (H) groups. Groups L, M, and H, respectively, received oral melatonin at 10, 20, and 50 mg/kg of BW (body weight) daily after inducing hyperglycemia by nicotinamide (NA)/ streptozotocin (STZ). After the six-week intervention, results showed that melatonin administration increased insulin level and performed lower area under the curve (AUC) in H group (p < 0.05). Melatonin could lower hepatic Malondialdehyde (MDA) level in all melatonin-treated groups and increase superoxide dismutase activity in H group (p < 0.05). Melatonin-treated groups revealed significant higher adiponectin in L group, and lower leptin/adiponectin ratio and leptin in M and H groups (p < 0.05). Melatonin could lower cholesterol and triglyceride in liver and decrease plasma cholesterol and low-density lipoprotein-cholesterol (LDL-C) in L group, and increase plasma high-density lipoprotein-cholesterol (HDL-C) in H group (p < 0.05). Above all, melatonin could decrease oxidative stress, increase the adiponectin level and improve dyslipidemia, especially in H group. These data support melatonin possibly being a helpful aid for treating hyperglycemia-related symptoms.

Melatonin inhibits snake venom and antivenom induced oxidative stress and augments treatment efficacy

Snakebite is a neglected health hazard. Its patho-physiology has largely been focused on systemic and local toxicities; whereas, venom and antivenom induced oxidative stress has long been ignored. Antivenom therapy although neutralizes venom lethality and saves many lives, remains ineffective against oxidative stress. This prompted us to complement antivenom with an antioxidant molecule melatonin that would protect against oxidative stress and increase the efficacy of the existing snakebite therapy. Here we show that D. russelli and E. carinatus venoms induce strong oxidative stress that persists even after antivenom administration in mice model. Additionally, antivenoms also induce oxidative stress. Polyvalent antivenom induce more oxidative stress than monovalent antivenom. Strikingly, antivenom and melatonin together not only inhibit venom and antivenom induced oxidative stress but also significantly reduce the neutralizing antivenom dose. This study provides a therapeutic potential for enhancing the existing snakebite therapy. The combined treatment of antivenom+melatonin would prevent the upsurge of oxidative stress as well as minimize the antivenom load. Thus the investigation offers immense scope for physicians and toxinologists to reinvestigate, design new strategies and think beyond the conventional mode of antivenom therapy.

Effects of Melatonin on Liver Injuries and Diseases

Liver injuries and diseases are serious health problems worldwide. Various factors, such as chemical pollutants, drugs, and alcohol, could induce liver injuries. Liver diseases involve a wide range of liver pathologies, including hepatic steatosis, fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocarcinoma. Despite all the studies performed up to now, therapy choices for liver injuries and diseases are very few. Therefore, the search for a new treatment that could safely and effectively block or reverse liver injuries and diseases remains a priority. Melatonin is a well-known natural antioxidant, and has many bioactivities. There are numerous studies investigating the effects of melatonin on liver injuries and diseases, and melatonin could regulate various molecular pathways, such as inflammation, proliferation, apoptosis, metastasis, and autophagy in different pathophysiological situations. Melatonin could be used for preventing and treating liver injuries and diseases. Herein, we conduct a review summarizing the potential roles of melatonin in liver injuries and diseases, paying special attention to the mechanisms of action.

Ameliorative effect of vanadyl(IV)-ascorbate complex on high-fat high-sucrose diet-induced hyperglycemia, insulin resistance, and oxidative stress in mice

There is mounting evidence demonstrating causative links between hyperglycemia, oxidative stress, and insulin resistance, the core pathophysiological features of type 2 diabetes mellitus. Using a combinational approach, we synthesized a vanadium-antioxidant (i.e., l-ascorbic acid) complex and examined its effect on insulin resistance and oxidative stress. This study was designed to examine whether vanadyl(IV)-ascorbate complex (VOAsc) would reduce oxidative stress, hyperglycemia, and insulin resistance in high-fat high-sucrose diet (HFSD)-induced type 2 diabetes in mice. Male C57BL/6J mice were fed a HFSD for 12 weeks to induce insulin resistance, rendering them diabetic. Diabetic mice were treated with rosiglitazone, sodium l-ascorbate, or VOAsc. At the end of treatment, fasting blood glucose, fasting serum insulin, homeostasis model assessment-insulin resistance index, and serum adipocytokine levels were measured. Serum levels of nitric oxide (NO) parameters were also determined. The liver was isolated and used for determination of malondialdehyde, reduced glutathione, and catalase levels, and superoxide dismutase and glutathione peroxidase activities. VOAsc groups exhibited significant reductions in serum adipocytokine and NO levels, and oxidative stress parameters compared to the corresponding values in the untreated diabetic mice. The results indicated that VOAsc is non-toxic. In conclusion, we identified VOAsc as a potentially effective adjunct therapy for the management of type 2 diabetes.

Oxidative stress-induced methemoglobinemia is the silent killer during snakebite: a novel and strategic neutralization by melatonin

Oxidative stress-induced methemoglobinemia remained an untouched area in venom pharmacology till date. This study for the first time explored the potential of animal venoms to oxidize hemoglobin to methemoglobin. In in vitro whole-blood assay, methemoglobin forming ability of venoms varied as Naja naja > Ophiophagus hannah > Echis carinatus > Daboia russellii > Apis mellifera > Mesobuthus tamulus > Hippasa partita. Being highly potential, N. naja venom was further studied to observe methemoglobin formation in RBCs and in combinations with PMNs and PBMCs, where maximum effect was observed in RBCs + PMNs combination. Naja naja venom/externally added methemoglobin-induced methemoglobin formation was in parallel with ROS generation in whole blood/RBCs/RBCs + PMNs/RBCs + PBMCs. In in vivo studies, the lethal dose (1 mg/kg body weight, i.p.) of N. naja venom readily induced methemoglobin formation, ROS generation, expression of inflammatory markers, and hypoxia-inducible factor-3α. Although the mice administered with three effective doses of antivenom recorded zero mortality; the methemoglobin and ROS levels remained high. However, one effective dose of antivenom when administered along with melatonin (1:50; venom/melatonin, w/w), not only offered 100% survival of experimental mice, but also significantly reduced methemoglobin level, and oxidative stress markers including hypoxia-inducible factor-3α. This study provides strong drive that, complementing melatonin would not only reduce the antivenom load, but for sure greatly increase the success rate of antivenom therapy and drastically minimize the global incidence of snakebite deaths. However, further detailed investigations are needed before translating the combined therapy towards the bed side.

Investigation of antidiabetic action of Antidesma bunius extract in type 1 diabetes

CONTEXT

Antidesma bunius L (Phyllanthaceae) is commonly known to local people in North-east Thailand as a medicinal plant.

OBJECTIVES

To investigate hypoglycaemic activities of methanolic extract of A. bunius in type 1 diabetes.

MATERIALS AND METHODS

A daily dose of A. bunius extract (250 mg/kg body weight) was given orally to alloxan-induced diabetic rats for 28 days. Blood glucose, insulin, TC, TG, amylase, lipase, liver glycogen were analysed.

RESULTS

Extract revealed a significant reduction in blood glucose level (80.5%) along with an increase in serum insulin (134%), lipase (90.7%) and liver glycogen level (160%). Also amylase (28.2%) activity, TC (40.2%), and TG (28.8%) levels were significantly decreased when compared with diabetic control rats. A. bunius extract improved the histo-architectural of the β-cells.

DISCUSSION AND CONCLUSION

The results suggested that A. bunius extract possess anti-diabetic activity, through the enhancement of hepatic glycogen storage and regeneration of the islet of Langerhans.