Advances and challenges in serine in the central nervous system: physicochemistry, physiology, and pharmacology.

Neurological disorders are the primary cause of human disability and mortality globally, however, current medications slightly alleviate some symptoms of degenerative diseases. Serine is an important amino acid for the brain function and involved in a variety of biosynthetic pathways and signal transduction processes. The imbalance of serine metabolism is associated with neurodegeneration, including neuroinflammation, oxidative stress and apoptosis. Altered activities of serine metabolizing enzymes and accumulation of serine metabolites affect the survival and function of nerve cells. Abnormal serine levels are observed in animal models with neurological diseases, but not all human studies, therefore, the maintenance of serine homeostasis is a potentially therapeutic strategy for neurological disorders. To date, physiological and pharmacological roles of serine in neurological diseases have not been systemically recapitulated, and the association between serine and neurological diseases is controversial. In this review, we summarize physicochemical properties of serine, biological processes of serine in the brain (source, biotransformation, and transport), and the application of serine in neurological diseases including Alzheimer's disease, schizophrenia, and depression. Here, we highlight physicochemistry, physiology, pharmacology, and therapeutic potentials of serine in the prevention and treatment of neurological dysfunction. Our work provides valuable hints for future investigation that will lead to a comprehensive understanding of serine and its metabolism in cellular physiology and pharmacology. Although broad by necessity, the review helps researchers to understand great potentials of serine in the prevention and treatment of neurological dysfunction.

Selenium intake is an effective strategy for the improvement of cognitive decline in low cognition older Americans.

Age-related cognitive decline is a prominent concern in older adults and selenium (Se) deficiency has been found to be associated with cognitive deficits. For the first time, the present study explored the association between Se intake and cognitive performance in older people with/without cognitive impairment using the data from the National Health and Nutrition Examination Survey 2011-2014. Weighted linear regression models were conducted to evaluate the association between dietary Se/total Se intakes and cognitive assessments. A total of 2387 participants were included. The significant positive association between dietary Se/total Se intakes and total scores of cognitive functioning tests existed only in the older people with low cognitive performance (p < 0.001), not in those with normal cognitive performance. In conclusion, Se intake was beneficial for cognitive decline only in the low cognition older people but failed in normal cognition older people.

New horizons for the role of selenium on cognitive function: advances and challenges.

Cognitive deficits associated with oxidative stress and the dysfunction of the central nervous system are present in some neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. Selenium (Se), an essential microelement, exhibits cognition-associated functions through selenoproteins mainly owing to its antioxidant property. Due to the disproportionate distribution of Se in the soil, the amount of Se varies greatly in various foods, resulting in a large proportion of people with Se deficiency worldwide. Numerous cell and animal experiments demonstrate Se deficiency-induced cognitive deficits and Se supplementation-improved cognitive performances. However, human studies yield inconsistent results and the mechanism of Se in cognition still remains elusive, which hinder the further exploration of Se in human cognition. To address the urgent issue, the review summarizes Se-contained foods (plant-based foods, animal-based foods, and Se supplements), brain selenoproteins, mechanisms of Se in cognition (improvement of synaptic plasticity, regulation of Zn2+ level, inhibition of ferroptosis, modulation of autophagy and de novo synthesis of L-serine), and effects of Se on cognitive deficits, as well as consequently sheds light on great potentials of Se in the prevention and treatment of cognitive deficits.

Identification of Factors on Blood Selenium Levels in the US Adults: A Cross-Sectional Study.

Selenium (Se) is an essential trace element for humans and its low or high concentration in vivo is associated with the high risk of many diseases. It is important to identify influential factors of Se status. The present study aimed to explore the association between several factors (Se intake, gender, age, race, education, body mass index (BMI), income, smoking and alcohol status) and blood Se concentration using the National Health and Nutrition Examination Survey 2017-2020 data. Demographic characteristics, physical examination, health interviews and diets were compared among quartiles of blood Se concentration using the Rao-Scott χ2 test. Se levels were compared between the different groups of factors studied, measuring the strength of their association. A total of 6205 participants were finally included. The normal reference ranges of blood Se concentration were 142.3 (2.5th percentile) and 240.8 µg/L (97.5th percentile), respectively. The mean values of dietary Se intake, total Se intake and blood Se concentration of the participants were 111.5 µg/day, 122.7 µg/day and 188.7 µg/L, respectively, indicating they were in the normal range. Total Se intake was the most important contributor of blood Se concentration. Gender, race, education status, income, BMI, smoking and alcohol status were associated with blood Se concentration.