Since the COVID-19 outbreak, studies across diverse countries have strongly pointed toward the emergence of a mental health crisis, with a dramatic increase in the prevalence of depressive psychopathology and suicidal tendencies. Vitamin D deficiency has been associated with an increased risk of mental health problems as well as individual responses to stress. Studies have discussed the relationship between low serum vitamin D concentrations and depressive symptoms, suggesting that maintaining adequate concentrations of serum vitamin D seems to have a protective effect against it. Vitamin D was found to contribute to improved serotonergic neurotransmission in the experimental model of depression by regulating serotonin metabolism. The signaling of 1,25-dihydroxyvitamin D3, the active form of vitamin D, through vitamin D receptor (VDR) induces the expression of the gene of tryptophan hydroxylase 2 (TPH2), influences the expression of serotonin reuptake transporter (SERT) as well as the levels of monoamine oxidase-A (MAO-A), the enzyme responsible for serotonin catabolism. Vitamin D also presents a relevant link with chronobiological interplay, which could influence the development of depressive symptoms when unbalance between light-dark cycles occurs. In this Perspective, we discussed the significant role of vitamin D in the elevation of stress-related depressive symptoms during the COVID-19 pandemic. It is suggested that vitamin D monitoring and, when deficiency is detected, supplementation could be considered as an important healthcare measure while lockdown and social isolation procedures last during the COVID-19 pandemic. Graphical Abstract Role of vitamin D in the development of depressive symptoms. The synthesis of vitamin D from sunlight is impaired by lockdown and social distance measures imposed by the governments around the world during COVID-10 pandemic. Endogenous vitamin D synthesis initiates in the skin when 7-dehydrocholesterol (7-DHC) is converted in pre-vitamin D3 and then vitamin D3 [25(OH)D3]. It is transported through blood circulation by the vitamin D binding protein (VDBP) to the liver, the kidney, and the brain, where can be converted in its the active form [1,25(OH)2D3]. In the brain, the biological effects of 1,25(OH)2D3 are largely mediated by vitamin D receptor (VDR) through genomic mechanisms, which influence several aspects of serotonin metabolism, such as increasing serotonin synthesis by induction of the tryptophan hydroxylase 2 (TPH2) gene expression; influencing the expression of serotonin reuptake transporter (SERT) and the levels of monoamine oxidase-A (MAO-A), responsible to serotonin catabolism; and indirectly may regulate the synthesis of melatonin that improve the circadian rhythm. This mechanism can be impaired during social isolation and consequent reduction of vitamin D due to low sun exposure during the pandemic, which could contribute to the development of depressive symptoms.
【저자키워드】 COVID-19, Vitamin D, cholecalciferol, social isolation, Depressive symptoms, Pandemics, 【초록키워드】 pandemic, Depression, melatonin, Stress, lockdown, mental health, COVID-19 pandemic, vitamin D deficiency, metabolism, Brain, kidney, Prevalence, Protein, COVID-19 outbreak, response, healthcare, Vitamin D receptor, VDR, mechanisms, genomic, expression, liver, mechanism, protective effect, binding, Signaling, Concentration, regulate, Government, reduction, deficiency, Serotonin, increased risk, enzyme, measure, depressive, dramatic increase, active form, blood circulation, serum vitamin D, Effect, endogenous, role, country, depressive symptom, IMPROVE, responsible, contribute, suggested, induce, influence, initiate, transported, COVID-10, mental health problem, TPH2,