Analysis of the effect of vitamin D supplementation and sex on Vdr, Cyp2r1 and Cyp27b1 gene expression in Wistar rats' tissues

A Network Pharmacology-Based Method to Explore the Therapeutic Effect of Honokiol on Diabetes with Comorbid Depression in Mice

The effective treatment of diabetes with comorbid depression is a big challenge so far. Honokiol, a bioactive compound from the dietary supplement Magnolia officinalis extract, possesses multiple health benefits. The present study aims to propose a network pharmacology-based method to elucidate potential targets of honokiol in treating diabetes with comorbid depression and related mechanisms. The antidepressant-like efficacy of honokiol was evaluated in high-fat diet (HFD) induced diabetic mice using animal behavior testing, immuno-staining and western blotting assay. Through network pharmacology analysis, retinoid X receptor alpha (RXRα) and vitamin D receptor (VDR) were identified as potential targets related to diabetes and depression. The stable binding conformation between honokiol and RXR/VDR was determined by molecular docking simulation. Moreover, hononkiol effectively alleviated depression-like behaviors in HFD diabetic mice, presented anti-diabetic and anti-neuroinflammatory functions, and protected the hippocampal neuroplasticity. Importantly, honokiol could activate RXR/VDR heterodimer in vivo. The beneficial effects of honokiol on HFD mice were significantly suppressed by UVI3003 (a RXR antagonist), while enhanced by calcitriol (a VDR agonist). Additionally, the disruption of autophagy in the hippocampus of HFD mice was ameliorated by honokiol, which was attenuated by UVI3003 but strengthened by calcitriol. Taken together, the data provide new evidence that honokiol exerts the antidepressant-like effect in HFD diabetic mice via activating RXR/VDR heterodimer to restore the balance of autophagy. Our findings indicate that the RXR/VDR-mediated signaling might be a potential target for treating diabetes with comorbid depression.

Vitamin D metabolism is altered during aging alone or combined with obesity in male mice

Aging and obesity are associated with a decrease in plasma 25-hydroxyvitamin D (25(OH)D) levels. In the context of a growing aging population and the rising incidence of obesity, we hypothesized that aging process, either independently or in combination with obesity, could influence vitamin D (VD) metabolism, consequently resulting in the reduced 25(OH)D plasma concentrations. C57BL/6JRJ young (6 months) and old (23 months) mice fed with control (CD) or high fat diet (HF) were compared. Plasma and adipose concentration of cholecalciferol and 25(OH)D and mRNA expression of genes coding for the main VD actors were analyzed. Aging was associated with a decrease in plasma 25(OH)D levels, whereas combined effect of obesity and aging did not generate a cumulative effect on plasma 25(OH)D levels. The mRNA expression of Cyp27a1, Cyp3a11, and Cyp2j6 were decreased in the liver during aging. Together, these regulations could explain the reduced 25-hydroxylation. Interestingly, the lack of cumulative reduction of 25(OH)D in aged and obese mice could be related to the strong induction of Cyp2j6. In kidneys, a complex modulation of Cyp27b1 and Cyp24a1 could contribute to the reduced 25-hydroxylation in the liver. In white adipose tissue, an induction of Cyp2r1 was observed during aging and obesity, together with an increase of 25(OH)D quantity, suggesting an exacerbated storage that may participated to the reduced plasma 25(OH)D levels. These findings support the notion that aging alone or combined with obesity, induces regulation of VD metabolism in the organs, beyond the classical reduction of epidermal VD precursor, which may contribute to the decrease in 25(OH)D levels.

Parathyroid hormone-vitamin D dynamics vary according to the definition of vitamin D deficiency in newborn infants

BACKGROUND

Parathyroid hormone (PTH) is an indirect functional indicator of vitamin D status. Risk of vitamin D deficiency, assessed using circulating 25-hydroxyvitamin D (25(OH)D), is defined as <30 nmol/L by the National Academy of Medicine and alternatively <25 nmol/L in the global consensus recommendation on prevention and management of nutritional rickets.

OBJECTIVE

To test PTH concentrations and the odds for elevated values according to vitamin D deficiency cut-points (<30 nmol/L, or <25 nmol/L) in newborn infants.

METHODS

Healthy term-born infants (n = 858) were recruited from Montreal, Canada (2016-2019). Obstetric data were obtained from medical records, and demographic factors surveyed. Immunoassays were used to measure newborn (24-36 h) serum PTH and 25(OH)D; 25(OH)D was standardized to National Institute of Standards and Technology (NIST) standard reference materials. Serum PTH was log-transformed before comparing serum 25(OH)D groups (<30 vs. ≥30; or <25 vs. ≥25 nmol/L) using ANCOVA adjusted for infant sex, type of delivery, parity, race, and family income. The odds of elevated PTH (>71.48 pg/mL) were tested using logistic regression, adjusted for the same covariates.

RESULTS

Infants (50.2 % female) were 39.6 ± 1.0 weeks gestational age (mean ± SD), and 3.41 ± 0.38 kg. Median serum 25(OH)D was 45.4 (IQR 23.2) nmol/L; 20.5 % had serum 25(OH)D < 30 nmol/L, and 12.4 % <25 nmol/L. Median serum PTH was 30.72 (IQR 33.90) pg/mL, elevated in 12.7 % overall, and higher in infants born with serum 25(OH)D < 25 vs. ≥25 nmol/L (35.96 (IQR 39.20) vs. 30.36 (IQR 32.93) pg/mL, p = 0.0158). The odds of elevated PTH were higher when serum 25(OH)D was <25 nmol/L (ORadj 2.13, 95 % CI: 1.23, 3.69). PTH concentration and the odds of being elevated did not differ according to the 30 nmol/L cut-point.

CONCLUSIONS

Based on this study, the definition of vitamin D deficiency relative to bone health as set by the National Academy of Medicine (<30 nmol/L) exceeds the threshold at which PTH is elevated in newborn infants.

VDR, SOD-2, and CYP24A1 Gene Expression in Different Genotypes of BsmI SNP of the Vitamin D Receptor Gene in Individuals with Hypovitaminosis

BACKGROUND

Hypovitaminosis D is a public health problem due to its implications for various diseases. Vitamin D has numerous functions, such as modulating the metabolism of cellular tissues, and it is expressed through the vitamin D receptor (VDR) gene that may influence gene expression modulation, which plays an important role in vitamin D metabolism.

OBJECTIVE

To evaluate the effect of the genotypes of BsmI single nucleotide polymorphism (SNP) of the VDR gene on VDR, SOD2, and CYP24A1 gene expression in individuals with low serum vitamin D levels.

METHODS

This was a cross-sectional analytical study. After signing the informed consent form, individuals were invited to participate and answered a structured questionnaire with identification data. Blood was collected for biochemical analysis, and vitamin D was measured by chemiluminescence; BsmI polymorphism was determined using real-time polymerase chain reaction (PCR) assays with TaqMan allelic discrimination, and gene expression was conducted by qRT-PCR using QuantiFast SYBR® Green PCR Master Mix. Data were analyzed using the SPSS 20.0 software, and differences were considered significant at p < 0.05.

RESULTS

98 individuals with vitamin D ≤ 20 ng/dL were evaluated, and the BsmI SNP of the VDR gene showed CYP24A1 overexpression and low SOD2 expression.

CONCLUSION

BsmI SNP of the VDR gene can modulate the expression of the genes evaluated without interfering with serum levels.

Overview of gene expression techniques with an emphasis on vitamin D related studies

Each cell controls when and how its genes must be expressed for proper function. Every function in a cell is driven by signaling molecules through various regulatory cascades. Different cells in a multicellular organism may express very different sets of genes, even though they contain the same DNA. The set of genes expressed in a cell determines the set of proteins and functional RNAs it contains, giving it its unique properties. Malfunction in gene expression harms the cell and can lead to the development of various disease conditions. The use of rapid high-throughput gene expression profiling unravels the complexity of human disease at various levels. Peripheral blood mononuclear cells (PBMC) have been used frequently to understand gene expression homeostasis in various disease conditions. However, more studies are required to validate whether PBMC gene expression patterns accurately reflect the expression of other cells or tissues. Vitamin D, which is responsible for a multitude of health consequences, is also an immune modulatory hormone with major biological activities in the innate and adaptive immune systems. Vitamin D exerts its diverse biological effects in target tissues by regulating gene expression and its deficiency, is recognized as a public health problem worldwide. Understanding the genetic factors that affect vitamin D has the potential benefit that it will make it easier to identify individuals who require supplementation. Different technological advances in gene expression can be used to identify and assess the severity of disease and aid in the development of novel therapeutic interventions. This review focuses on different gene expression approaches and various clinical studies of vitamin D to investigate the role of gene expression in identifying the molecular signature of the disease.

Sex differences in vitamin D metabolism, serum levels and action

The ubiquity of vitamin D metabolising enzymes and vitamin D receptors in mammalian organisms suggests that vitamin D has pleiotropic effects. There are quite a few studies indicating the anticancer, cardioprotective and antidiabetic effects of vitamin D; however, the best-documented actions of vitamin D are the regulation of Ca-phosphate balance and its effect on immune function.Vitamin D levels in organisms are modulated by many environmental and non-environmental factors. One potential factor that may influence vitamin D levels and effects is the sex of the individuals studied. This review focuses on the scientific evidence indicating different synthesis and metabolism of vitamin D in females and males, mainly from PubMed database sources. The article verifies the sex differences in vitamin D levels reported around the world. Moreover, the different effects of vitamin D on the musculoskeletal, cardiovascular, nervous and immune systems, as well as cancer in males and females, were discussed.Most studies addressing sex differences in vitamin D levels and effects are observational studies with conflicting results. Therefore, carefully designed clinical trials and experiments on animal models should be carried out to determine the role of non-environmental factors that may differentiate vitamin D levels in females and males.

Effect of Vitamin-D-Enriched Edible Mushrooms on Vitamin D Status, Bone Health and Expression of CYP2R1, CYP27B1 and VDR Gene in Wistar Rats

Vitamin D deficiency is highly prevalent in India and worldwide. Mushrooms are important nutritional foods, and in this context shiitake (Lentinula edodes), button (Agaricus bisporus) and oyster (Pleurotus ostreatus) mushrooms are known for their bioactive properties. The application of ultraviolet (UV) irradiation for the production of substantial amounts of vitamin D2 is well established. Levels of serum 25-hydroxy vitamin D (25-OHD), parathyroid hormone (PTH), calcium, phosphorus and alkaline phosphatase (ALP) were significantly (p < 0.05) improved in vitamin-D-deficient rats after feeding with UVB irradiated mushrooms for 4 weeks. Further, microscopic observations indicate an improvement in the osteoid area and the reduction in trabecular separation of the femur bone. In addition, the level of expression of the vitamin D receptor (VDR) gene and genes metabolizing vitamin D were explored. It was observed that in mushroom-fed and vitamin-D-supplemented groups, there was upregulation of CYP2R1 and VDR, while there was downregulation of CYP27B1 in the liver. Further, CYP2R1 was downregulated, while CYP27B1 and VDR were upregulated in kidney tissue.