Effects of the addition of insulin-transferrin-selenium (ITS) and/or metformin to the in vitro maturation of porcine oocytes on cytoplasmic maturation and embryo development.

CONTEXT: One of the main problems of porcine in vitro maturation (IVM) is incomplete cytoplasmatic maturation. Nuclear and cytoplasmic maturation will determine the future success of fertilisation and embryo development. Insulin-transferrin-selenium (ITS) has insulin-like and antioxidant effects, and metformin (M) is an insulin-sensitiser and antioxidant drug. AIMS: To assess the effects of adding ITS and/or M in porcine IVM media on cytoplasmic maturation and early embryo development. METHODS: Cumulus -oocyte complexes (COC) were IVM with M (10-4 M), ITS (0.1% v/v), M+ITS or no adding (Control). KEY RESULTS: ITS increased glucose consumption compared to Control and M (P <0.01), and M+ITS did not differ from ITS or Control. Redox balance: M, ITS and M+ITS increased glutathione (P <0.01) and decreased lipid peroxidation (P <0.005). The viability of cumulus cells by flow cytometry increased with M (P <0.005) and decreased with ITS (P <0.001); M+ITS did not differ from Control. After IVF, M increased penetration and decreased male pronucleus (P <0.05). Embryo development: cleavage increased with M (P <0.05), and blastocysts increased with ITS and M+ITS (P <0.05). The number of blastocyst cells increased with ITS (P <0.05). CONCLUSIONS: Adding ITS and M+ITS to porcine IVM media benefits embryo development to blastocysts, but ITS alone has better effects than M+ITS. IMPLICATIONS: ITS is an excellent tool to improve IVM and embryo development after IVF in pigs.

The coculture of in vitro produced porcine embryos and oviductal epithelial cells improves blastocyst formation and modify embryo quality.

The efficiency of in vitro embryo production in mammals is influenced by variables associated with culture conditions during maturation, fertilization, and embryonic development. The embryos obtained often exhibit low quality due to suboptimal in vitro culture conditions compared to the in vivo environment. Co-culturing gametes and embryos with somatic cells has been developed to enhance in vitro culture conditions. This study aimed to assess the impact of coculturing in vitro-produced porcine embryos with porcine oviductal epithelial cells (POEC) on embryo development and quality. Firstly, a pure culture of POEC suitable for coculture systems was established. The epithelial origin of the cells was confirmed by the expression of E-cadherin and cytokeratin. The expression pattern of hormone receptors aligned with the diestrous oviduct, and POEC also secreted oviductal glycoprotein type 1 (OVGP-1). Secondly, POEC from passage 1 (POEC-1) were used to coculture with in vitro-produced porcine embryos. A successful coculture system was established without the addition of fetal bovine serum as a supplement. Coculturing POEC-1 in monolayers with in vitro-produced porcine embryos during the initial two days of culture enhanced the percentage of blastocysts and their hatching. Although the coculture did not alter the number of cells in the blastocysts or apoptosis assessed by TUNEL, it significantly reduced reactive oxygen species (ROS) levels in cleaved porcine embryos. This study represents the first report evaluating the quality of porcine embryos produced by IVF in coculture systems and assessing ROS levels in cleaved porcine embryos obtained by IVF.

DMSO supplementation during in vitro maturation of bovine oocytes improves blastocyst rate and quality.

The molecule Dimethyl sulfoxide is widely used as drug solvent. However, its antioxidant property was poorly explored. In this study, we evaluated the effect of DMSO supplementation during oocyte in vitro maturation (IVM) on embryo development and quality. Bovine oocytes were matured with different DMSO concentrations (0, 0.1, 0.25, 0.5, 0.75, 1 and 10% v:v) followed by in vitro fertilization. Subsequently, quality indicators such as gene expression of SOX2, OCT4, CDX2, SOD1, oocyte and embryo redox status and DNA damage were evaluated. Polar body extrusion and blastocyst rates increased with 0.5% v:v DMSO. Moreover, first polar body extrusion and blastocyst rates did not increase with 1%, and 10% of DMSO reduced polar body extrusion and did not produce blastocyst. Optimal concentration of DMSO for the use on the maturation was estimated at around 0.45% v:v. Supplementation with 0.5% v:v DMSO has not affected mRNA abundance of genes key in blastocyst, however 0.75% increased gene expression of OCT4 and SOX2. Oocytes matured with 0.5% v:v DMSO and blastocyst from DMSO group showed reduced lipid peroxidation respect control. Total Glutathione concentrations increased in blastocyst stage in DMSO group. DMSO increased the total cell number of blastocysts but not TUNEL positive cells. In conclusion, our results suggest that low DMSO concentrations used during bovine oocytes in vitro maturation increases the maturation, as well as the blastocyst rate and its quality, without demonstrating deleterious effect on embryo cells.

Effects of dehydroepiandrosterone on ovarian cystogenesis and immune function.

The purpose of the present report was to study the possible relationship between ovarian functionality and the immune response during cystogenesis induced by androgenization with dehydroepiandrosterone (DHEA). Daily injection of DHEA (6 mg/kg body weight) for 20 consecutive days induced ovarian cysts in BALB/c mice. As markers of ovarian function, serum estradiol (E) and progesterone (P) and the ovarian inmunomodulator prostaglandin E (PGE) were analyzed. In order to know how the integrity of the tissue was altered after induction of cystogenesis, the oxidative status was also evaluated. Serum E and P levels, and ovarian PGE concentration, were increased in animals with cysts compared with healthy controls. The oxidant status (quantified by malondialdehyde (MDA) formed after the breakdown of the cellular membrane by free radical mechanisms) was augmented, meanwhile the antioxidant (evaluated by the glutathione (GSH) content) diminished during the induction of cystogenesis. Both immunohistochemical and flow cytometry assays demonstrated that DHEA treatment increased the number of T lymphocytes infiltrating ovarian tissue. Therefore, while ovarian controls showed equivalent expression of CD4+ and CD8+ T cell subsets, injection of DHEA yielded a selective ovarian T cell infiltration as demonstrated by enhanced CD8+ and diminished CD4+ T lymphocyte expression. These results show that the development of cysts involves changes in ovarian function and an imbalance in the oxidant-antioxidant equilibrium. We observed also both an increased and selective T lymphocyte infiltration.

Role of the N, N'-dimethylbiguanide metformin in the treatment of female prepuberal BALB/c mice hyperandrogenized with dehydroepiandrosterone.

The present study investigated the role of the N, N{'}-dimethylbiguanide metformin (50 mg/100 g body weight in 0.05 ml water, given orally with a canulla) in the prevention of endocrine and immune disorders provoked by the hyperandrogenization with dehydroepiandrosterone (DHEA) in prepuberal BALB/c mice. The treatment with DHEA (6 mg/100 g body weight in 0.1 ml oil) for 20 consecutive days, recreates a mouse model that resembles some aspects of the human polycystic ovary syndrome (PCOS). The treatment with DHEA did not modify either body mass index (BMI) or blood glucose levels, but did increase fasting insulin levels when compared with controls. Markers of ovarian function - serum estradiol (E), progesterone (P) and ovarian prostaglandin E (PGE) - were evaluated. The treatment with DHEA increased serum E and P levels while ovarian PGE diminished. When metformin was administered together with DHEA, serum insulin, E and P levels, and ovarian PGE values did not differ when compared with controls. Using flow cytometry assays we found that the treatment with DHEA diminished the percentage of the CD4 + T lymphocyte population and increased the percentage of the CD8 + T lymphocyte population from both ovarian tissue and retroperitoneal lymph nodes. However, when metformin was administered together with DHEA, the percentages of CD4 + and CD8 + T lymphocyte populations from both ovarian tissue and retroperitoneal lymph nodes were similar to those observed in controls. Finally, when DHEA was administered alone it increased the serum tumor necrosis factor-alpha (TNF-alpha ) levels when compared with controls; however, when metformin was administered together with DHEA, serum TNF-alpha levels were similar to controls. These results indicate that metformin is able, directly or indirectly, to avoid the endocrine and immune alterations produced when mice are hyperandrogenized with DHEA.

The influence of dehydroepiandrosterone on early pregnancy in mice.

The aim of the present report was to study the role of high levels of dehydroepiandrosterone (DHEA) on the ovarian function and embryonic resorption during early pregnancy in BALB/c mice. Pregnant animals were injected with DHEA following both the post-implantatory (DHEA-2) and peri-implantatory (DHEA-6) models. Morphological studies of implantation sites showed 40% of embryonic resorption in the DHEA-2 group while 100% of resorption was observed in the DHEA-6 group. Serum samples of both DHEA-2 and DHEA-6 groups showed higher estradiol levels and a lower progesterone concentration than those of control groups. Ovarian prostaglandin E levels after both DHEA-2 and DHEA-6 treatments increased when compared to control groups. The antioxidant metabolite glutathione diminished during both DHEA treatments. In summary, the data presented here suggest that DHEA treatment during early pregnancy modulates the ovarian function and is responsible for embryonic resorption with different degrees depending on when it is administered.