Comparative expression profiles of genes related to oocyte development in goats after long-term feeding with biodiesel castor industry residues

IGF-1 treatment during in vitro maturation improves developmental potential of ovine oocytes through the regulation of PI3K/Akt and apoptosis signaling

This study aimed to assess the effect of the insulin-like grow factor 1 (IGF-1) treatment during in vitro maturation on the gene expression and developmental ability of ovine oocytes. Ovine cumulus-oocyte complexes (COC) were matured in vitro without (control) or with the supplementation of IGF-1 (100 ng/ml) and then subjected to in vitro fertilization and culture. The rate of oocyte maturation and embryo development was recorded and expression of the selected genes (involved in the PI3K/Akt and apoptosis signaling) was assessed in the matured oocytes. The IGF-1 treatment significantly (p < .05) improved the oocyte maturation rate (%) as compared to the control (81.5 ± 2.40 vs. 73.6 ± 0.94). Similarly, as compared to the control, the IGF-1 treatment significantly (p < .05) improved the rate (%) of cleavage (54.7 ± 1.58 vs. 67.2 ± 3.65) and the formation of 4-8 cell embryos (30.7 ± 2.89 vs. 44.1 ± 4.01) and morula (20.7 ± 2.08 vs. 32.8 ± 2.78). The IGF-1 treatment significantly (p < .05) upregulated the expression of IGF1R, PI3KR1, AKT1 and BCL2 and downregulated the expression of GSK3β, FOXO3 and CASP9 in the matured oocytes. In conclusion, the IGF-1 treatment significantly improved the developmental competence of ovine oocytes through the regulation of the PI3K/Akt and apoptosis signaling.

Temporal expression of cumulus cell marker genes during in vitro maturation and oocyte developmental competence

PURPOSE

Cumulus cells (CC) play important roles in oocyte development and cumulus expressed genes can be used as markers for oocyte quality. This study aimed to investigate temporal changes in the expression of cumulus marker genes during oocyte maturation as possible biomarkers of embryo developmental competence in ovine.

METHODS

Gene expression was assessed in the CC of the BCB+ (developmentally competent) and BCB- (developmentally poor) oocytes at 0, 12, and 24 h of in vitro maturation (IVM). Further, the association between the temporal cumulus gene expression and in vitro oocyte and embryo development was assessed.

RESULTS

The maturation and blastocyst formation rates were found significantly greater for the BCB+ than the BCB- oocytes. At the 0 h of IVM, a significant upregulation in the expression of PTGS2, STAR, SDC2, LHR, FGF2, BCL2, IL7RA, HSPA1A, and IFNT was observed in the CC of the poor (BCB-) as compared to the competent (BCB+) oocytes. In contrast, it was observed that as maturation progressed, the cumulus expression of most of the favorable genes was reduced and was found significantly downregulated at the completion of IVM in the poor as compared to the competent oocytes.

CONCLUSIONS

The study revealed noticeable differences in the cumulus gene expression profile at different stages of IVM between ovine oocytes of differential developmental ability. The results indicated that the loss of cumulus gene expression along the maturation period in the poor oocytes was related to their intrinsic poor quality in the ovarian follicle.

Caprine ovarian follicle requirements differ between preantral and early antral stages after IVC in medium supplemented with GH and VEGF alone or in combination

The aim of the present study was to evaluate the effect of growth hormone (GH) and vascular endothelial growth factor (VEGF) added alone, sequentially or in combination, in the presence of insulin at physiological concentration (10 ng/mL) on the IVC of two different follicular categories: preantral (experiment 1; Exp.1) and early antral (experiment 2; Exp.2). Isolated follicles were individually cultured for 24 (Exp.1) and 18 days (Exp.2) in the following treatments: αMEM⁺ (Control), or Control medium supplemented with 50 ng/mL GH (GH), 100 ng/mL VEGF (VEGF), the combination of both (GH + VEGF), GH during the first 12 days and VEGF from Day 12 until the end of the culture (GH/VEGF) and vice versa (VEGF/GH). At the end of the culture, cumulus-oocyte complexes from in vitro-grown follicles were recovered and subjected to IVM. The following end points were evaluated: Follicle morphology, growth rates and antrum formation, production of estradiol, progesterone and testosterone, oocyte viability and meiotic stage, as well as relative expression of LHR, Amh, HAS2, PTGS2, CYP17, CYP19A1, and 3βHSD. A considerable amount of viable fully grown oocytes were recovered after the IVC of early antral follicles in all treatments. Nevertheless, the GH treatment presented the highest percentage of fully grown oocytes (60%), mean oocyte diameter (117.74 ± 2.61 μm), and meiotic resumption (50%). Furthermore, GH treatment produced higher (P < 0.05) rates of metaphase II oocytes than all the other treatments, and similar LHR, Amh, and PTGS2 transcript levels to in vivo. Contrary to early antral follicles, preantral follicles were not affected by medium supplementation. In conclusion, the addition of GH to a culture medium containing physiological concentrations of insulin improves oocyte growth and maturation after the IVC of goat early antral follicles.