Oral Vitamin D supplementation impacts gene expression in granulosa cells in women undergoing IVF

Relevance of Vitamin D and Its Deficiency for the Ovarian Follicle and the Oocyte: An Update

For many years, vitamin D (VD) has been known to be an essential micronutrient with important relevance not only for the skeletal system, but also for numerous other mammalian organ systems. Low levels of VD result in a VD deficiency, which is a global health problem. Moreover, VD deficiencies are linked to several pathologies, for instance, diseases of the cardiovascular system, diabetes mellitus, or sub- and infertility. In the past two decades, an increasing body of evidence has shown that adequate physiological levels of VD are crucial for the female gamete and its microenvironment, and VD deficiency has been associated with decreased live birth rates among women undergoing in vitro fertilization (IVF). With regard to the female reproductive tract, VD receptors (VDRs) have been detected in the ovary, endometrium, and the placenta. Although it has been reported that VD seems to be relevant for both calcium-dependent and independent pathways, its relevance for the oocyte’s developmental competence and life span remains elusive. Therefore, herein, we aim to provide an update on the importance of VD and VD deficiency for the oocyte and the follicular microenvironment.

Female infertility and diet, is there a role for a personalized nutritional approach in assisted reproductive technologies? A Narrative Review

Female infertility is a major public health concern and a global challenge. It is a disorder of the reproductive system, defined as the inability to achieve a clinical pregnancy. Nutrition and other environmental factors are found to impact reproductive health in women as well as the outcome of assisted reproductive technologies (ART). Dietary factors, such as polyunsaturated fatty acids (PUFA), fiber as well as the intake of Mediterranean diet appear to exert beneficial effects on female reproductive outcomes. The exact mechanisms associating diet to female fertility are yet to be identified, although genomic, epigenomic, and microbial pathways may be implicated. This review aims to summarize the current knowledge on the impact of dietary components on female reproduction and ART outcomes, and to discuss the relevant interplay of diet with genome, epigenome and microbial composition.

Impact of vitamin D3 supplementation on the in vitro growth of mouse preantral follicles

OBJECTIVE

We investigated the impact of vitamin D3 (VD3) supplementation during mouse preantral follicle culture in vitro and the mRNA expression of 25-hydroxylase (CYP2R1), 1-alpha-hydroxylase (CYP27B1), and vitamin D receptor (VDR) in mouse ovarian follicles at different stages.

METHODS

Preantral follicles were retrieved from 39 BDF1 mice (7-8 weeks old) and then cultured in vitro for 12 days under VD3 supplementation (0, 25, and 50 pg/mL). Follicular development and the final oocyte acquisition were assessed. Preantral follicles were retrieved from 15 other BDF1 mice (7-8 weeks old) and cultured without VD3 supplementation. Three stages of mouse ovarian follicles were obtained (preantral, antral, and ruptured follicles). Total RNA was extracted from the pooled cells (from 20 follicles at each stage), and then reverse transcriptase-polymerase chain reaction was performed to identify mRNA for CYP2R1, CYP27B1, and VDR.

RESULTS

The survival of preantral follicles, rates of antrum formation and ruptured follicles (per initiated follicle) and the number of total or mature oocytes were all comparable among the three groups. Both CYP2R1 and CYP27B1 were expressed in antral and ruptured follicles, but not in preantral follicles. VDR was expressed in all three follicular stages.

CONCLUSION

VD3 supplementation in vitro (25 or 50 pg/mL) did not enhance mouse follicular development or final oocyte acquisition. Follicular stage-specific expression of CYP2R1, CYP27B1, and VDR was observed.