Essential Hypertension and Oxidative Stress: Novel Future Perspectives.

Among cardiovascular diseases, hypertension is one of the main risk factors predisposing to fatal complications. Oxidative stress and chronic inflammation have been identified as potentially responsible for the development of endothelial damage and vascular stiffness, two of the primum movens of hypertension and cardiovascular diseases. Based on these data, we conducted an open-label randomized study, first, to evaluate the endothelial damage and vascular stiffness in hypertense patients; second, to test the effect of supplementation with a physiological antioxidant (melatonin 1 mg/day for 1 year) in patients with essential hypertension vs. hypertensive controls. Twenty-three patients of either gender were enrolled and randomized 1:1 in two groups (control and supplemented group). The plasmatic total antioxidant capacity (as a marker of oxidative stress), blood pressure, arterial stiffness, and peripheral endothelial function were evaluated at the beginning of the study and after 1 year in both groups. Our results showed that arterial stiffness improved significantly (p = 0.022) in supplemented patients. The endothelial function increased too, even if not significantly (p = 0.688), after 1 year of melatonin administration. Moreover, the supplemented group showed a significative reduction in TAC levels (p = 0.041) correlated with the improvement of arterial stiffness. These data suggest that melatonin may play an important role in reducing the serum levels of TAC and, consequently, in improving arterial stiffness.

Role of melatonin in autism spectrum disorders in a male murine transgenic model: Study in the prefrontal cortex.

Autism spectrum disorders (ASDs) are a group of clinically heterogeneous neurodevelopmental disorders sharing common features related to impaired social and communication abilities in addition to stereotyped behaviors. ASD patients present encephalic morphological, physiological, and biomolecular alterations with low levels of melatonin due to alterations in its pathways. Therefore, even if ASDs have traditionally been framed as behavioral disorders, several lines of evidence are accumulating that ASDs are characterized by certain anatomical and physiological abnormalities, including oxidative stress and inflammation in peripheral biomarkers, but likewise present in human brain tissue also characterized by alterations in synaptic remodeling and neuromodulation. Melatonin has also protective and antioxidant properties, so we can therefore hypothesize that alterations in melatonin's pathways may be one of the causes of the symptomatology of autism. The aim of the present study was to analyze the beneficial effect induced by melatonin administration and its possible mechanism of action in a transgenic mouse model of autism, immediately after weaning. The male mice were daily treated per os with melatonin (10 mg/Kg/day) or vehicle for 8 weeks starting from the sixth week of life. The antioxidant modulation, the GABAergic/glutamatergic impairment, and the synaptic remodeling in the prefrontal cortex have been evaluated. Social and repetitive behaviors were also evaluated. The behavioral results showed no statistical evidences, instead the immunohistochemical results indicated the ability of melatonin to promote the activity of antioxidant system, the GABAergic/glutamatergic equilibrium, and the synaptic remodeling. The results show that melatonin may be a possible adjuvant therapeutic strategy in ASDs.

Cold Press Pomegranate Seed Oil Attenuates Dietary-Obesity Induced Hepatic Steatosis and Fibrosis through Antioxidant and Mitochondrial Pathways in Obese Mice.

AIM: Obesity is associated with metabolic syndrome, hypertension, dyslipidemia, nonalcoholic fatty liver disease (NAFLD), and type 2 diabetes. In this study, we investigated whether the dietary supplementation of pomegranate seed oil (PSO) exerted a protective effect on liver lipid uptake, fibrosis, and mitochondrial function in a mouse model of obesity and insulin resistance. METHOD: In this in vivo study, eight-week-old C57BL/6J male mice were fed with a high fat diet (HFD) for 24 weeks and then were divided into three groups as follows: group (1) Lean; group (n = 6) (2) HF diet; group (n = 6) (3) HF diet treated with PSO (40 mL/kg food) (n = 6) for eight additional weeks starting at 24 weeks. Physiological parameters, lipid droplet accumulation, inflammatory biomarkers, antioxidant biomarkers, mitochondrial biogenesis, insulin sensitivity, and hepatic fibrosis were determined to examine whether PSO intervention prevents obesity-associated metabolic syndrome. RESULTS: The PSO group displayed an increase in oxygen consumption, as well as a decrease in fasting glucose and blood pressure (p < 0.05) when compared to the HFD-fed mice group. PSO increased both the activity and expression of hepatic HO-1, downregulated inflammatory adipokines, and decreased hepatic fibrosis. PSO increased the levels of thermogenic genes, mitochondrial signaling, and lipid metabolism through increases in Mfn2, OPA-1, PRDM 16, and PGC1α. Furthermore, PSO upregulated obesity-mediated hepatic insulin receptor phosphorylation Tyr-972, p-IRB tyr1146, and pAMPK, thereby decreasing insulin resistance. CONCLUSIONS: These results indicated that PSO decreased obesity-mediated insulin resistance and the progression of hepatic fibrosis through an improved liver signaling, as manifested by increased insulin receptor phosphorylation and thermogenic genes. Furthermore, our findings indicate a potential therapeutic role for PSO in the prevention of obesity-associated NAFLD, NASH, and other metabolic disorders.

NLRP3 Inflammasome Modulation by Melatonin Supplementation in Chronic Pristane-Induced Lupus Nephritis.

Lupus nephritis (LN) is a kidney inflammatory disease caused by systemic lupus erythematosus (SLE). NLRP3 inflammasome activation is implicated in LN pathogenesis, suggesting its potential targets for LN treatment. Melatonin, an endogenous indoleamine, is considered an important multitasking molecule that has been reported to have anti-inflammatory effects by inhibiting nuclear factor-kappa B (NF-κB)-mediated inflammatory responses in vivo. This molecule has also protective effects against the activation of the inflammasomes and, in particular, the NLRP3 inflammasome. Thus, this work evaluated the effect of melatonin on morphological alteration and NLRP3 inflammasome activation in LN pristane mouse models. To evaluate the melatonin effects in these mice, we studied the renal cytoarchitecture by means of morphological analyses and immunohistochemical expression of specific markers related to oxidative stress, inflammation and inflammasome activation. Our results showed that melatonin attenuates pristane-induced LN through restoring of morphology and attenuation of oxidative stress and inflammation through a pathway that inhibited activation of NLRP3 inflammasome signaling. Our data clearly demonstrate that melatonin has protective activity on lupus nephritis in these mice that is highly associated with its effect on enhancing the Nrf2 antioxidant signaling pathway and decreasing renal NLRP3 inflammasome activation.

Mitochondrial Dysfunction in Skeletal Muscle of a Fibromyalgia Model: The Potential Benefits of Melatonin.

Fibromyalgia syndrome (FMS) is considered a musculoskeletal disorder associated to other symptoms including chronic pain. Since the hypothesis of FMS etiogenesis is consistent with mitochondrial dysfunction and oxidative stress, we evaluated the pathophysiological correlation among these factors studying some proteins involved in the mitochondrial homeostasis. We focused our attention on the roles of peroxisome proliferator activated receptor gamma coactivator-1alpha (PGC-1α), mitofusin2 (Mfn2), and coenzyme Q10 (CoQ10) in reserpine-induced myalgic (RIM) rats that manifest fibromyalgia-like chronic pain symptoms. First, we underlined that RIM rats are a good model for studying the pathophysiology of FMS and moreover, we found that PGC-1α, Mfn2, and CoQ10 are involved in FMS. In fact, their expressions were reduced in gastrocnemius muscle determining an incorrect mitochondrial homeostasis. Today, none of the currently available drugs are fully effective against the symptoms of this disease and they, often, induce several adverse events; hence, many scientists have taken on the challenge of searching for non-pharmacological treatments. Another goal of this study was therefore the evaluation of the potential benefits of melatonin, an endogenous indoleamine having several functions including its potent capacity to induce antioxidant enzymes and to determine the protective or reparative mechanisms in the cells. We observed that melatonin supplementation significantly preserved all the studied parameters, counteracting oxidative stress in RIM rats and confirming that this indoleamine should be taken in consideration for improving health and/or counteract mitochondrial related diseases.

Dietary Melatonin Supplementation Could Be a Promising Preventing/Therapeutic Approach for a Variety of Liver Diseases.

In the therapeutic strategies, the role of diet is a well-established factor that can also have an important role in liver diseases. Melatonin, identified in animals, has many antioxidant properties and it was after discovered also in plants, named phytomelatonin. These substances have a positive effect during aging and in pathological conditions too. In particular, it is important to underline that the amount of melatonin produced by pineal gland in human decreases during lifetime and its reduction in blood could be related to pathological conditions in which mitochondria and oxidative stress play a pivotal role. Moreover, it has been indicated that melatonin/phytomelatonin containing foods may provide dietary melatonin, so their ingestion through balanced diets could be sufficient to confer health benefits. In this review, the classification of liver diseases and an overview of the most important aspects of melatonin/phytomelatonin, concerning the differences among their synthesis, their presence in foods and their role in health and diseases, are summarized. The findings suggest that melatonin/phytomelatonin supplementation with diet should be considered important in preventing different disease settings, in particular in liver. Currently, more studies are needed to strengthen the potential beneficial effects of melatonin/phytomelatonin in liver diseases and to better clarify the molecular mechanisms of action.

Melatonin Modulation of Sirtuin-1 Attenuates Liver Injury in a Hypercholesterolemic Mouse Model.

Hypercholesterolemia increases and exacerbates stress signals leading also to liver damage (LD) and failure. Sirtuin1 (SIRT1) is involved in lifespan extension and it plays an essential role in hepatic lipid metabolism. However, its involvement in liver hypercholesterolemic damage is not yet completely defined. This in vivo study evaluated the role of SIRT1 in the hypercholesterolemic-related LD and, then, investigated how oral supplementation of melatonin, pleiotropic indoleamine, may be protective. Control mice and apolipoprotein E-deficient mice (ApoE-/-) of 6 and 15 weeks of age were treated or not treated with melatonin at the dose of 10 mg/kg/day for 9 weeks. In this study, we evaluated serum biochemical markers, liver SIRT1 expression, and oxidative stress markers. We observed that hypercholesterolemia increased significantly serum cholesterol and triglycerides, reduced significantly liver SIRT1, and, in turn, induced hepatic oxidative stress in untreated ApoE-/- mice with respect to control mice. Interestingly, melatonin treatment improved serum biochemical markers and hepatic morphological impairment and inhibited oxidative stress through its antioxidant properties and also by SIRT1 upregulation. In summary, melatonin oral supplementation may represent a new protective approach to block hypercholesterolemic liver alterations involving also a SIRT1-dependent mechanism.

Protective effects of quercetin treatment in a pristane-induced mouse model of lupus nephritis.

INTRODUCTION: Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus. As murine models of LN are valuable tools to better understand its pathophysiology and to search for new effective treatments, we investigated the effects of the bioflavonoid quercetin on pristane-induced LN mice through histomorphological analyses. METHODS: Immunofluorescence and biochemical assays were used to evaluate the expression of markers of inflammation (interleukin-6, IL-6; tumour necrosis factor-α, TNF-α), oxidative stress (catalase, CAT; superoxide dismutase 1, SOD1; thiobarbituric acid reactive substances, TBARS), apoptosis (Bax), and fibrosis (transforming growth factor-ß1, TGF-ß1). Glomerular and tubular ultrastructure was analysed, and tissue messenger RNA of podocin, podoplanin and α3ß1-integrin were quantified using the real-time polymerase chain reaction. RESULTS: Pristane-induced LN mice showed severe kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation, high expression of the pro-fibrotic, apoptotic and prooxidant markers and reduction of antioxidants. In the kidney ultrastructure, foot process (FP) effacement, apoptotic mesangial cells and abnormal mitochondria with disrupted cristae were observed, along with suppressed tissue mRNA of podocin, podoplanin and α3ß1-integrin. Treatment with quercetin in the pristane-induced LN mice model was nephroprotective, decreasing proteinuria levels and significantly lowering tissue expression of IL-6, TNF-α, TGF-ß1, Bax and TBARS. Simultaneously, quercetin significantly increased CAT and SOD1 expressions in these mice. In addition, it was observed improvement of the kidney ultrastructure, and tissue mRNA of podocin, but not podoplanin and α3ß1-integrin, was restored to the levels found in the control mice. CONCLUSION: In conclusion, these findings provide experimental evidence of the renoprotective effects of quercetin in the pristane-induced LN mice model. We suggest that quercetin effectively ameliorates the kidney damage caused by pristane, a bioflavonoid to be further evaluated as a new therapeutic strategy in this disease.

Oral supplementation of melatonin protects against lupus nephritis renal injury in a pristane-induced lupus mouse model.

AIMS: Since lupus nephritis (LN) etiopathogenesis is not fully understood, herein we investigated the morphological basis of LN in mice induced with pristane. MAIN METHODS: To evaluate the melatonin effects in these animals, we studied the renal cytoarchitecture by means of morphological analyses, immunofluorescence expression of specific markers related to fibrosis, oxidative stress, inflammation and apoptosis. KEY FINDINGS: We observed that pristane-LN mice have serious alterations in the kidney cytoarchitecture, i.e. tubular degeneration, glomerular hypercellularity, matrix mesangial expansion and interstitial inflammation. The pristane-induced LN mice treated with melatonin exhibited a well preserved cytoarchitecture. SIGNIFICANCE: Our results document that LN etiopathogenesis is related to both tubular damage and glomerular lesions. We suggest that it is essential to take in consideration both these lesions for LN diagnosis and classification. Clearly, we show that the use of melatonin may be a possible therapeutic strategy for improvement the renal injury in this disorder.

Oral Supplementation of Melatonin Protects against Fibromyalgia-Related Skeletal Muscle Alterations in Reserpine-Induced Myalgia Rats.

Fibromyalgia is a chronic syndrome characterized by widespread musculoskeletal pain and an extensive array of other symptoms including disordered sleep, fatigue, depression and anxiety. Important factors involved in the pathogenic process of fibromyalgia are inflammation and oxidative stress, suggesting that ant-inflammatory and/or antioxidant supplementation might be effective in the management and modulation of this syndrome. Recent evidence suggests that melatonin may be suitable for this purpose due to its well known ant-inflammatory, antioxidant and analgesic effects. Thus, in the current study, the effects of the oral supplementation of melatonin against fibromyalgia-related skeletal muscle alterations were evaluated. In detail, 90 Sprague Dawley rats were randomly treated with reserpine, to reproduce the pathogenic process of fibromyalgia and thereafter they received melatonin. The animals treated with reserpine showed moderate alterations at hind limb skeletal muscles level and had difficulty in moving, together with significant morphological and ultrastructural alterations and expression of inflammatory and oxidative stress markers in the gastrocnemius muscle. Interestingly, melatonin, dose and/or time dependently, reduced the difficulties in spontaneous motor activity and the musculoskeletal morphostructural, inflammatory, and oxidative stress alterations. This study suggests that melatonin in vivo may be an effective tool in the management of fibromyalgia-related musculoskeletal morphofunctional damage.

Melatonin Pharmacological Blood Levels Increase Total Antioxidant Capacity in Critically Ill Patients.

In this study, the aim was to test the biochemical effects of melatonin supplementation in Intensive Care Unit (ICU) patients, since their blood levels are decreased. Sixty-four patients were enrolled in the study. From the evening of the 3rd ICU day, patients were randomized to receive oral melatonin (3 mg, group M) or placebo (group P) twice daily, at 20:00 and 24:00, until discharged. Blood was taken (at 00:00 and 14:00), on the 3rd ICU day to assess basal nocturnal melatonin values, and then during the treatment period on the 4th and 8th ICU days. Melatonin, total antioxidant capacity, and oxidative stress were evaluated in serum. Melatonin circadian rhythm before treatment was similar in the two groups, with a partial preservation of the cycle. Four hours from the 1st administration (4th ICU day, 00:00), melatonin levels increased to 2514 (982.3; 7148) pg·mL-1 in group M vs. 20.3 (14.7; 62.3) pg·mL-1 in group P (p < 0.001). After five treatment days (8th ICU day), melatonin absorption showed a repetitive trend in group M, while in group P nocturnal secretion (00:00) was impaired: 20 (11.5; 34.5) pg·mL-1 vs. 33.8 (25.0; 62.2) on the 3rd day (p = 0.029). Immediately from the beginning of treatment, the total antioxidant capacity was significantly higher in melatonin treated subjects at 00:00; a significant correlation was found between total antioxidant capacity and blood melatonin values (ρ = 0.328; p < 0.001). The proposed enteral administration protocol was adequate, even in the early phase, to enhance melatonin blood levels and to protect the patients from oxidative stress. The antioxidant effect of melatonin could play a meaningful role in the care and well-being of these patients.

Melatonin reduces obesity and restores adipokine patterns and metabolism in obese (ob/ob) mice.

The increasing incidence of obesity, leading to metabolic complications, is now recognized as a major public health problem. The adipocytes are not merely energy-storing cells, but they play crucial roles in the development of the so-called metabolic syndrome due to the adipocyte-derived bioactive factors such as adipokines, cytokines, and growth factors. The dysregulated production and secretion of adipokines seen in obesity is linked to the pathogenesis of the metabolic disease processes. In this study, we hypothesized that dietary melatonin administration would support an anti-inflammatory response and play an important role in energy metabolism in subcutaneous and visceral adipose tissues of obese mice and so may counteract some of the disruptive effects of obesity. Lean and obese mice (ob/ob) received melatonin or vehicle in drinking water for 8 weeks. Thereafter, they were evaluated for morphologic alteration, inflammatory cell infiltration, and the adipokine patterns in visceral and subcutaneous white fat depots. In obese mice treated with vehicle, we observed a significant increase in fat depots, inflammation, and a dysregulation of the adipokine network. In particular, we measured a significant reduction of adiponectin and an increase of tumor necrosis factor α, resistin, and visfatin in adipose tissue deposits. These changes were partially reversed when melatonin was supplemented to obese mice. Melatonin supplementation by regulating inflammatory infiltration ameliorates obesity-induced adipokine alteration, whereas melatonin administration in lean mice was unaffected. Thus, it is likely that melatonin would be provided in supplement form to control some of the disruptive effects on the basis of obesity pathogenic process.

Effects of melatonin and Pycnogenol on small artery structure and function in spontaneously hypertensive rats.

It was suggested that oxidative stress has a key role in the development of endothelial dysfunction, as well as microvascular structural alterations. Therefore, we have investigated 2 substances with antioxidant properties: melatonin and Pycnogenol. We treated 7 spontaneously hypertensive rats (SHRs) with melatonin and 7 with Pycnogenol for 6 weeks. We compared results obtained with those observed in 7 SHRs and 7 Wistar-Kyoto normotensive control rats kept untreated. Mesenteric small resistance arteries were dissected and mounted on a wire myograph, and a concentration-response curve to acetylcholine was performed. Aortic contents of metalloproteinase 2, Bax, inducible NO synthase, and cyclooxygenase 2 were evaluated, together with the aortic content of total collagen and collagen subtypes and apoptosis rate. A small reduction in systolic blood pressure was observed. A significant improvement in mesenteric small resistance artery structure and endothelial function was observed in rats treated with Pycnogenol and melatonin. Total aortic collagen content was significantly greater in untreated SHRs compared with Wistar-Kyoto control rats, whereas a full normalization was observed in treated rats. Apoptosis rate was increased in the aortas of untreated SHRs compared with Wistar-Kyoto control rats; an even more pronounced increase was observed in treated rats. Bax and metalloproteinase 2 expressions changed accordingly. Cyclooxygenase 2 and inducible NO synthase were more expressed in the aortas of untreated SHRs compared with Wistar-Kyoto control rats; this pattern was normalized by both treatments. In conclusion, our data suggest that treatment with Pycnogenol and melatonin may protect the vasculature, partly independent of blood pressure reduction, probably through their antioxidant effects.