The Vital Role of Melatonin and Its Metabolites in the Neuroprotection and Retardation of Brain Aging.

While primarily produced in the pineal gland, melatonin's influence goes beyond its well-known role in regulating sleep, nighttime metabolism, and circadian rhythms, in the field of chronobiology. A plethora of new data demonstrates melatonin to be a very powerful molecule, being a potent ROS/RNS scavenger with anti-inflammatory, immunoregulatory, and oncostatic properties. Melatonin and its metabolites exert multiple beneficial effects in cutaneous and systemic aging. This review is focused on the neuroprotective role of melatonin during aging. Melatonin has an anti-aging capacity, retarding the rate of healthy brain aging and the development of age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis, etc. Melatonin, as well as its metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), can reduce oxidative brain damage by shielding mitochondria from dysfunction during the aging process. Melatonin could also be implicated in the treatment of neurodegenerative conditions, by modifying their characteristic low-grade neuroinflammation. It can either prevent the initiation of inflammatory responses or attenuate the ongoing inflammation. Drawing on the current knowledge, this review discusses the potential benefits of melatonin supplementation in preventing and managing cognitive impairment and neurodegenerative diseases.

Attenuation of Hypothyroidism-Induced Cognitive Impairment by Modulating Serotonin Mediation.

Thyroid hormones play an important role in the modeling of neural networks in the brain. Besides its metabolic effects, thyroid dysfunction, and hypothyroidism in particular, is frequently associated with cognitive decline and depressive-like behavior. The current study aimed to examine the changes in behavior, cognition, and memory in rats with propylthiouracil-induced overt hypothyroidism. The behavior and cognition were assessed using the open field test, T-maze, and novel object recognition test. We found significant differences in the behavioral patterns of the hypothyroid animals showing a reduction in locomotor activity, frequency of rearing, and impaired memory function compared to the euthyroid controls. As serotonin is an essential biomarker regulating cognition and mood, we tried to modulate the serotonin mediation in hypothyroid animals through tryptophan administration. Treatment with 5-hydroxy-tryptophan (5-OH-TRP) intraperitoneally for 10 days or directly into the hippocampus as a single injection led to attenuation of the hypothyroidism-induced cognitive and memory decline. A staggering amount of research is suggesting that the common denominators in the pathophysiology of depression and the behavior changes in hypothyroidism are the hippocampal complex and the distorted serotonin metabolism. In our study, it was observed a significant alleviation of cognitive impairment and an improvement of memory performance in hypothyroid rats after 5-OH-TRP administration. Current results are promising and may serve as groundwork for further investigation of functional and structural changes in the hippocampus during a hypothyroid state, and in particular, the effects of serotonin mediation in hypothyroid-associated depressive-like behavior.

Platelet Distribution Width and Increased D-Dimer at Admission Predicts Subsequent Development of ARDS in COVID-19 Patients.

In the current pandemic of coronavirus disease (COVID-19), the identification of the patients admitted with severe infection-who are disposed to a high risk of acute respiratory distress syndrome (ARDS) development, is of a major significance for the determination of the appropriate therapeutic strategy. Laboratory records in admission were retrospectively reviewed from 493 cases of severe COVID-19 divided into two groups: Group 1 with ARDS and Group 2 without ARDS. The platelet distribution width (PDW) difference between Group 1 and Group 2 is significant-15.10 ± 2.08 fl for those who developed ARDS versus 12.94 ± 2.12 fl for those without ARDS. The sensitivity and the specificity of this parameter is lower than that of D-dimer. After grouping of the PDW values into intervals and combining them with the rate of increase in D-dimer (D-PDWf index) to form a forecasting index, a significant increase in the specificity and sensitivity of the two parameters is identified-area under the ROC curve (AUC) is 0.874 for D-PDWf index, with respective AUC for PDW 0.768 and AUC for D-dimer 0.777. Conclusion: PDW is a significant predictive parameter at admission for subsequent development of ARDS in patients, with increased significance in combination with the degree of increase in D-dimer.

Effect of a Ketogenic Diet on Oxidative Posttranslational Protein Modifications and Brain Homogenate Denaturation in the Kindling Model of Epilepsy in Mice.

This study focused on the ketogenic diet (KD) effects on oxidative posttranslational protein modification (PPM) as presumptive factors implicated in epileptogenesis. A 28-day of KD treatment was performed. The corneal kindling model of epileptogenesis was used. Four groups of adult male ICR mice (25-30 g) were randomized in standard rodent chow (SRC) group, KD-treatment group; SRC + kindling group; KD + kindling group (n = 10 each). Advanced oxidation protein products (AOPP) and protein carbonyl contents of brain homogenates together with differential scanning calorimetry (DSC) were evaluated. Two exothermic transitions (Exo1 and Exo2) were explored after deconvolution of the thermograms. Factor analysis was applied. The protective effect of KD in the kindling model was demonstrated with both decreased seizure score and increased seizure latency. KD significantly decreased glucose and increased ketone bodies (KB) in blood. Despite its antiseizure effect, the KD increased the AOPP level and the brain proteome's exothermic transitions, suggestive for qualitative modifications. The ratio of the two exothermic peaks (Exo2/Exo1) of the thermograms from the KD vs. SRC treated group differed more than twice (3.7 vs. 1.6). Kindling introduced the opposite effect, changing this ratio to 2.7 for the KD + kindling group. Kindling significantly increased glucose and KB in the blood whereas decreased the BW under the SRC treatment. Kindling decreased carbonyl proteins in the brain irrespectively of the diet. Further evaluations are needed to assess the nature of correspondence of calorimetric images of the brain homogenates with PPM.

Commentary regarding "neuroactive compounds in foods: Occurrence, mechanism and potential health effects".

A letter to the Editor focusing on some safety concerns about melatonin, provoked by the article "Neuroactive compounds in foods: Occurrence, mechanism and potential health effects" published in Journal of Food Research International.

Antioxidant Effect of Alpha-Lipoic Acid in 6-Hydroxydopamine Unilateral Intrastriatal Injected Rats.

The toxin 6-hydroxydopamine (6-OHDA) is a highly oxidizable dopamine (DA) analog that is widely used for reproducing several cell processes identified in Parkinson's disease (PD). Due to the close similarity of its neurotoxic mechanism to those of DA, it is suitable as a model for testing the effects of potentially neuroprotective drugs. This study aimed to evaluate the effect of alpha-lipoic acid (LA) on brain oxidative stress (OS) in unilateral intrastriatal (6-OHDA) injected rats. Forty male Wistar rats, four months old (220-260 g), were evaluated. Half of them received LA (35 mg/kg i.p.) from the start to the end of the experiment. On day 2 of the trial, ten LA-supplemented rats and ten non-LA-supplemented rats were subjected to the apomorphine test. Brain homogenates were evaluated for thiobarbituric acid-reactive substances (TBARS) and glutathione peroxidase (GPx) activity. The same evaluation procedures were repeated on day 14 with the remaining animals. An increased TBARS level and decreased GPx activity, suggestive for OS, were recorded in homogenates on day 14 vs. day 2 of the experiment in the 6-OHDA treated rats. The simultaneous application of LA mitigated these changes. Our study demonstrates that the low dose of LA could be of value for decreasing the OS of the neurotoxic 6-OHDA, supporting the need for further studies of the benefit of LA treatment in PD.

Differentiation of obese patients at moderate or higher Findrisc score based on their atherogenic index.

OBJECTIVES: The purpose of this study was to reveal different subgroups of patients with at least moderate risk of developing diabetes in the next 10 years, based on clustering of cardiovascular risk factors. METHODS: We performed a one-center cross-sectional study of adult patients (n = 109, median age 45 years) with Findrisc score of above 11 out of 26 maximum. We included in the cluster analysis anthropometrics, lipid and carbohydrate parameters obtained in oral glucose tolerance test (OGTT), insulin, C-peptide, creatinine, C-reactive protein, liver enzymes, beta-cell function, insulin sensitivity and insulin resistance (HOMA calculations). We also evaluated the atherogenic index of plasma (AIP). RESULTS: We identified three metabolic phenotypes of patients with at least moderate Findrisc score-one 'male' (cluster AM, n = 24), and two 'female' phenotypes (cluster AW, n = 9 and cluster BW, n = 76). Men were almost homogenous for their metabolic phenotype, with lower fat percentage than women (p < .05). Most of the women (cluster BW, n = 76) presented with better metabolic pattern i.e. lower insulin resistance, lower C-reactive protein, lower degree of obesity and visceral fat rating (p < .05), despite the higher fat percentage (p < .05). Some of the women, however, (cluster AW, n = 9) presented with parameters very similar to that of men (cluster AM) and significantly higher than in cluster BW. Despite the lack of significant differences in lipid parameters among clusters, AIP was significantly lower in cluster BW (p < .05). CONCLUSION: Most of the women presented with clearly less unfavorable atherogenic risk than men. Two different phenotypes of obese women with at least moderate Findrisc score were revealed, and the level of inflammation seems to be the main discriminant factor. Larger prospective studies are required to elucidate whether those are really two different pathogenically phenotypes or if they belong to the same phenotype's continuum.