Melatonin in Neurodevelopmental Disorders: A Critical Literature Review

Innovative mechanisms of micro- and nanoplastic-induced brain injury: Emphasis on the microbiota-gut-brain axis

Micro- and nanoplastics (MNPs), emerging environmental pollutants, infiltrate marine, terrestrial, and freshwater systems via diverse pathways, culminating in their accumulation in the human body through food chain transmission, posing potential health risks. Researches have demonstrated that MNPs disrupt gut microbiota equilibrium and compromise intestinal barrier integrity, as well as traverse the blood-brain barrier, leading to brain damage. Moreover, the complex interaction between the gut and the nervous system, facilitated by the "gut-brain axis," indicates an additional pathway for MNPs-induced brain damage. This has intensified scientific interest in the intercommunication between MNPs and the gut-brain axis. While existing studies have documented microbial imbalances and metabolic disruptions subsequent to MNPs exposure, the precise mechanisms by which the microbiota-gut-brain axis contributes to MNPs-induced central nervous system damage remain unclear. This review synthesizes current knowledge on the microbiota-gut-brain axis, elucidating the pathogenesis of MNPs-induced gut microbiota dysbiosis and its consequent brain injury. It emphasizes the complex interrelation between MNPs and the microbiota-gut-brain axis, advocating for the gut microbiota as a novel therapeutic target to alleviate MNP-induced brain harm.

The impact of skin-to-skin contact upon stress in preterm infants in a neonatal intensive care unit

Introduction

Neonatal stress significantly affects the early adaptation, maturation and long-term development of preterm infants.

The objective of the study

To investigate the effect of skin-to-skin contact (SSC) on stress level in preterm infants.

Materials and methods

The research was a prospective study. Stress indicators (cortisol, melatonin) were measured before the SSC began (pre-intervention level) and after this intervention (post-intervention).

Results

The study included 150 preterm infants in the NICU with gestational age (GA) ≤36 weeks. Pre-intervention salivary cortisol level was higher in extremely and very preterm neonates compared to moderate and late preterm newborns (p = 0.028), in children with low Apgar scores (p = 0.041), in those who were on mechanical ventilation (p = 0.005), and suffered neonatal sepsis (p = 0.005). Pre-intervention melatonin level was lower in children with low Apgar scores (p = 0.032). Salivary cortisol levels were significantly decreased after SSC in preterm infants [pre-intervention: 0.294 (0.111; 0.854) μg/dL vs. post-intervention: 0.127 (0.070; 0.229) μg/dL, p < 0.001], and urinary melatonin levels were significantly increased after SSC [pre-intervention: 4.01 (2.48; 6.34) ng/mL vs. post-intervention: 5.48 (3.39; 9.17) ng/mL, p < 0.001]. A greater reduction in cortisol levels after skin-to-skin contact was revealed in infants with a lower gestational age (p = 0.022), in boys compared to girls (p = 0.012), in infants with respiratory distress syndrome (p = 0.048), in those who had mechanical ventilation compared to non-ventilated neonates (p = 0.008), and in infants with seizures (p = 0.036). The melatonin levels increased more intensively in infants with low Apgar scores (p = 0.002), and in those with late-onset sepsis (p = 0.006).

Conclusion

The reduction in cortisol levels and the increase in melatonin levels provided strong evidence that SSC ameliorated the NICU-related stress in preterm infants. We found higher indicators of stress and more dramatic responses to SSC in reducing indicators of stress in infants with lower GA than in infants with higher GA, indicating that SSC may be even more important for lower GA infants. The infants who need SSC the most should not be denied the care they need to reduce the stress they experience from being born too soon and continuing their gestational development in the stressful environment of the NICU.

The relationship between oxidative balance score and circadian syndrome: evidence from the NHANES 2005-2018

Background

The oxidative balance score (OBS) is a composite indicator that evaluates the balance between pro-oxidants and antioxidants in one's diet and lifestyle. However, the relationship between OBS and circadian syndrome (CircS) has remained unexplored. This investigation aimed to determine a correlation between OBS and CircS.

Methods

This population-based study examined 7,202 participants from the 2005 to 2018 National Health and Nutrition Examination Survey (NHANES), 1,433 of whom had CircS. We utilized weighted multivariate logistic regression, trend tests, subgroup analysis, and interaction tests to evaluate the correlation between OBS (total OBS, dietary OBS, and lifestyle OBS) and CircS. Restricted cubic splines (RCS) models and threshold effect analysis were used to explore nonlinear relationships.

Results

Multivariate logistic regression analysis indicated that the protective factor for CircS was a high OBS level (total OBS: Odds ratio (OR) = 0.95, 95% Confidence interval (CI): 0.93-0.97; dietary OBS: OR = 0.98, 95% CI: 0.96-1.00; lifestyle OBS: OR = 0.65, 95% CI: 0.61-0.69). Compared to the quartile 1 group, OBS (total OBS, dietary OBS, and lifestyle OBS) was negatively and statistically significantly associated with the risk of developing Circs in the quartile 4 group (total OBS: OR = 0.47, 95% CI: 0.32-0.70; dietary OBS: OR = 0.69, 95% CI: 0.48-0.99; lifestyle OBS: OR = 0.07, 95% CI: 0.04-0.11). According to subgroup analysis and interaction tests, there was an interaction effect between the association of lifestyle OBS and CircS in terms of education level (p for interaction = 0.01). Furthermore, we observed a nonlinear negative relationship between lifestyle OBS and CircS prevalence, with inflection points at 6 (p for nonlinearity = 0.002).

Conclusion

The results showed a substantial negative connection between OBS and CircS. Encouraging foods filled with antioxidants and antioxidant-rich lifestyles may reduce the risk of CircS.

The potential influence of melatonin on mitochondrial quality control: a review

Mitochondria are critical for cellular energetic metabolism, intracellular signaling orchestration and programmed death regulation. Therefore, mitochondrial dysfunction is associated with various pathogeneses. The maintenance of mitochondrial homeostasis and functional recovery after injury are coordinated by mitochondrial biogenesis, dynamics and autophagy, which are collectively referred to as mitochondrial quality control. There is increasing evidence that mitochondria are important targets for melatonin to exert protective effects under pathological conditions. Melatonin, an evolutionarily conserved tryptophan metabolite, can be synthesized, transported and metabolized in mitochondria. In this review, we summarize the important role of melatonin in the damaged mitochondria elimination and mitochondrial energy supply recovery by regulating mitochondrial quality control, which may provide new strategies for clinical treatment of mitochondria-related diseases.