Pharmacological and biochemical studies on the protective effects of melatonin during stress-induced behavioral and immunological changes in relation to oxidative stress in rats

Effects of Melatonin on Cardiac Injury and Inflammatory Biomarkers in Patients Undergoing Coronary Artery Bypass Graft Surgery: a Meta-analysis

INTRODUCTION

The antiinflammatory and antioxidative effects of melatonin have been established in recent years. Several studies indicate that oxidative stress and inflammation are key drivers of post-coronary artery bypass graft (CABG) surgery complications. In the present study, we aimed to investigate the effects of melatonin on cardiac injury and inflammatory biomarkers in CABG candidates.

METHODS

Embase, Medline/PubMed, Web of Science, Scopus, and the Cochrane library were searched up to 5 June 2022. All randomized controlled trials examining cardiac injury and inflammatory biomarkers of CABG patients who received melatonin were included. The random-effects model was utilized to perform the analysis.

RESULTS

A total of 947 citations were retrieved through database searches. Finally, five articles (six trials with 342 patients) were included after the screening. Melatonin supplementation led to a significant reduction in cardiac troponin I (CTnI) [weighted mean difference(WMD): -2.28 ng/ml; 95% CI -2.87, -1.69; P < 0.01; I²: 91.25%] and high sensitivity-C reactive protein (hs-CRP) levels (WMD: -0.62 mg/L; 95% CI -0.73, -0.5; P < 0.01; I²: 99.98%) in patients undergoing CABG surgery. We found a nonsignificant decrease in creatine kinase isoenzyme muscle/brain (CK-MB) levels (WMD: -2.87 ng/ml; 95% CI -5.97, 0.23; P = 0.07; I²: 99.98%) after melatonin supplementation. No publication bias was found according to Egger's test.

CONCLUSION

Melatonin supplementation may be useful in reducing cardiac injury and inflammatory biomarkers in CABG candidates. Future studies should investigate the clinical significance of these findings.

Pharmacological, Biochemical and Immunological Studies on Protective Effect of Mangiferin in 6-Hydroxydopamine (6-OHDA)-Induced Parkinson's Disease in Rats

Background:

Parkinson’s disease is a neurodegenerative disorder and is marked by inflammation and death of neurons in the striatum region of the midbrain. It has been reported that expression of NF-κB increases during Parkinson’s disease, which promotes oxidative stress, stimulates release of proinflammatory cytokines, and induces expression of nitric oxide. Therefore, in this study, we have used mangiferin a specific NF-κB inhibitor. Mangiferin is a polyphenolic compound traditionally used for its antioxidant and anti-inflammatory properties.

Methods:

The study utilized male Wistar rats weighing 200–250 g (56 rats; n = 8/group). On day “0,” stereotaxic surgery of rats was done to induce 6-hydroxydopamine lesioning in rats. Coordinates for substantia nigra were anteroposterior-2 mm, mediolateral-5 mm and dorsoventral-8.2 mm. After 14 days, those rats which show at least 210 contralateral rotations after administration of apomorphine (0.5 mg/kg S.C.) were selected for the study and were given treatment for 28 days. On day 28 of treatment, rats were subjected to behavioral studies to evaluate the effect of mangiferin and their brains were taken out after euthanasia to perform biochemical, molecular and immunological studies.

Results:

Treatment with mangiferin significantly improves the key parameters of locomotor activity and oxidative stress and reduces the parameters of inflammatory stress. Also, the activity of caspases was reduced. Significant decrease in activity of both cyclooxygenase 1 and 2 was also observed. Maximum improvement in all parameters was observed in rats treated with grouping of mangiferin 45 µg/kg and levodopa 10 mg/kg. Treatment with levodopa alone has no significant effect on biochemical and molecular parameters though it significantly improves behavioral parameters.

Conclusion:

Current treatment of Parkinson’s disease does not target progression of Parkinson’s disease. Results of this study suggest that mangiferin has protective effect in hemi-Parkinsonian rats. Therefore, the combination therapy of mangiferin and levodopa can be helpful in management of Parkinson’s disease.

Melatonin treatment affects changes in adrenal gene expression of catecholamine biosynthesizing enzymes and norepinephrine transporter in the rat model of chronic-stress-induced depression

This study investigated the effects of melatonin treatment on adrenal catecholamine content, synthesis, uptake, and vesicular transport induced by the chronic unpredictable mild stress (CUMS) model of depression in rats. This entailed quantifying the norepinephrine, epinephrine, mRNA, and protein levels of tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), norepinephrine transporter (NET), and vesicular monoamine transporter 2 (VMAT2) in the adrenal medulla. CUMS caused a significant depletion of norepinephrine stores and protein levels of TH, DBH, and NET, whereas the gene expression of PNMT was increased. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in norepinephrine content and the protein expression of TH, DBH, and NET in the adrenal medulla of chronically stressed rats. The present study demonstrates the stimulatory effect of melatonin on adrenomedullary synthesis, the uptake and content of catecholamine in the rat model of chronic stress-induced depression.

The role of melatonin in targeting cell signaling pathways in neurodegeneration

Neurodegenerative diseases are typified by neuronal loss associated with progressive dysfunction and clinical presentation. Neurodegenerative diseases are characterized by the intra- and extracellular conglomeration of misfolded proteins that occur because of abnormal protein dynamics and genetic manipulations; these trigger processes of cell death in these disorders. The disrupted signaling mechanisms involved are oxidative stress-mediated mitochondrial and calcium signaling deregulation, alterations in immune and inflammatory signaling, disruption of autophagic integrity, proteostasis dysfunction, and anomalies in the insulin, Notch, and Wnt/β-catenin signaling pathways. Herein, we accentuate some of the contemporary translational approaches made in characterizing the underlying mechanisms of neurodegeneration. Melatonin-induced cognitive enhancement and inhibition of oxidative signaling substantiates the efficacy of melatonin in combating neurodegenerative processes. Our review considers in detail the possible roles of melatonin in understanding the synergistic pathogenic mechanisms between aggregated proteins and in regulating, modulating, and preventing the altered signaling mechanisms discovered in cellular and animal models along with clinical evaluations pertaining to neurodegeneration. Furthermore, this review showcases the therapeutic potential of melatonin in preventing and treating neurodegenerative diseases with optimum prognosis.

Effects of N-acetyl cysteine and melatonin on early reperfusion injury in patients undergoing coronary artery bypass grafting: A randomized, open-labeled, placebo-controlled trial

OBJECTIVES

This study assessed the efficacy of oral consumption of N-acetyl cysteine (NAC) and melatonin (ML) in reducing early reperfusion injury and acute oxidative stress in patients undergoing coronary artery bypass grafting (CABG) with respect to the measurements of cardiac troponin I, lactate, malondealdehyde (MDA), and tumor necrosis factor-α (TNF-α) levels in the blood.

METHODS

This study was a randomized, open-label, placebo-controlled trial. Eighty eight patients, aged between 39 to 76 years and eligible for CABG, were recruited and randomly assigned into 3 intervention groups through a simple randomization method and underwent CABG surgery. Blood samples were withdrawn from arterial line, before the induction of anesthesia (before the start of surgery), after incision (before aortic cross-clamping), during global ischemia (during aortic cross-clamping), after aortic cross-clamping (on set of reperfusion), 15 minutes after reperfusion, and after recovery at the intense care unit. The blood samples were analyzed for troponin I, lactate, MDA and TNF-α levels.

RESULTS

There was no significant difference in influencing variables among the groups at the baseline. Overall mean troponin I, lactate, and TNF- α levels were significantly different between the intervention groups (all P < .001) at the recovery phase. Post-hoc pairwise comparisons showed that the differences of mean serum levels between ML and control groups were statistically significant for MDA, TNF- α, lactate, and troponin I (P < .001, P = .001, and P = .001, respectively). The differences between NAC and control groups and between ML and NAC groups were only significant for mean lactate level (P < .001).

CONCLUSION

The current study revealed that ML and NAC are potent antioxidants with similar efficacy in terms of reducing CABG related cardiac injury and oxidative stress with the dosage employed for the intervention.

Pharmacological studies on the anti-inflammatory and immunomodulatory role of pentoxifylline and its interaction with nitric oxide (NO) in experimental arthritis in rats

AIM

Present study was designed to evaluate protective effects of pentoxifylline and its potentiation with low dose of nitric oxide (NO) modulators in adjuvant-induced experimental arthritis in rats.

METHOD

Wistar rats (200-300 g, n = 8 per group) of both sexes were used in the study. On day "0" experimental arthritis was induced by injecting 0.2 ml of Complete Freund's adjuvant (CFA) in sub-planter region of right hind paw of animals. Pentoxifylline treatment alone and in combination with NO modulators was given (i.p.) from day 14 to 28. Various arthritic parameters were recorded and blood and joint synovial fluid was collected for biochemical analysis.

RESULTS

CFA inoculation significantly increases (1) arthritic index (2) ankle diameter (3) paw volume (4) histopathology score (5) serum TNF-α, IL-6, IL-1β and synovial TNF-α levels (p < 0.001) (6) serum Th₁ and Th₂ cytokine levels g) MDA levels in rat paw tissue homogenates (7) serum NF-κB levels. Significant decrease in serum IL-10 levels and SOD activity was observed in rats after CFA inoculation. Decrease in body weight and suppressed general quality of life of CFA inoculated rats was also observed. These CFA-induced arthritic changes were significantly reversed by pentoxifylline alone and in combination with low dose of NO modulators (p < 0.05).

CONCLUSION

These results are suggestive of protective effects of pentoxifylline and its potentiation in combination with low dose of NO modulators. These results may provide new pharmacological therapy for management of rheumatoid arthritis (RA).