VDR, CYP2R1 and CYP27B1 Genes Are Differentially Expressed in Male`s and Females Tissues of Wistar Rats

Effect of vitamin D on gene expression has been widely investigated in vitro; however, in vivo action of vitamin D supplementation has been much less analysed in this context. Moreover, recent findings suggest that the effect of vitamin D supplementation may be sex-specific. The aim of our study was to investigate how vitamin D supplementation affects the expression of vdr, cyp2r1 and cyp27b1 genes in the liver, fat, brain and kidney of male and female rats. 36 adult Wistars rats (18 male and 18 females) were divided into 3 groups obtaining the same standard diet, differing only in the dose of vitamin D (group I - no supplementation, group II 1000 IU/kg of vitamin D, group III 5000 IU/kg of vitamin D). After 3 months of the experiment, animals were euthanised, and samples of tissues were collected from all animals. RNA was isolated using the Purelink RNA isolation kit (Thermofisher). RNA was reverse transcribed using High-Capacity cDNA Reverse Transcription Kit (Thermofisher). qPCR was performed using TaqMan™ assays and TaqMan™ Fast Advanced Master Mix on Quant Studio 7 instrument (Thermofisher). Data were analysed using SAS software. In the liver, we observed that the expression of the vdr gene was ~5 fold higher and cyp2r1 was ~2 fold higher in females compared to males (p<0.0003) (p<0.0002) respectively. In adipose tissue expression of cyp27b1 was ~1.8 fold higher (p<0.014) in females compared to males. In the kidney expression of vdr and cyp2r1 was slightly higher in females (fold change- (fc) 1.18 p<0.03) (fc=1.37, p<0.0001), while expression of cyp27b1 was 1.7 fold higher in males (p<0.013). In the brain, we observed slightly increased expression of cyp2r1 and cyp27b1 genes in females when compared to males (fc=1.14 p<0.0001), fc=1.23 p<0.01). Supplementation with 5000 IU/kg of vitamin D resulted in the decrease in the expression of vdr, cyp2r1 and cyp27b1 in the kidney when both sexes were analysed together(p<0.0127, p<0.0326, p<0.0326) but this decline was only statistically significant for vdr in males when sexes were analysed separately (p<0,0403). In the liver of males expression of vdr gene tended to increase and expression of cyp27b1 tended to decrease after vitamin D supplementation (p<0.06) (p<0.0501). In the adipose of males expression of cyp27b1 was downregulated by the high dose of vitamin D (p<0.04) but not in females. In the brain of males, we observed a slight decrease in the expression of cyp2r1 in a group obtaining 5000 IU/kg of vitamin D when compared to animals obtaining 1000 IU/kg (p<0.025). Concluding, our study shows that in a number of tissues of Wistar rats, expression of vdr, cyp27b1, and cyp2r1 is higher in females when compared to males. The only exception is the expression of cyp27b1 in the kidney, where it is higher in males. Moreover, the effect of vitamin D supplementation on the expression of these genes is weak and more evident in males and when high doses (5000 IU/kg) of vitamin D was used.