Regulatory role of Wnt signal in the oestradiol synthesis of different size categories of ovarian follicles in buffalo (Bubalus bubalis).

The aim of the present study was to understand the role of Wnt signal in ovarian oestradiol synthesis in various size categories of ovarian follicles. A six-day cell culture system was adopted to test the effect of a Wnt inhibitor i.e. Inhibitor of Wnt response (IWR) on the ovarian granulosa cell oestradiol synthesis and associated genes related to oestradiol synthesis and Wnt signalling (CYP19A1, CCND2, WNT2, FZD6, DVL1, APC, AXIN2, CTNNB1) in buffalo. It was conducted with four groups: Group 1: control, Group 2: control + FSH, Group 3: IWR, Group 4: IWR + FSH. No significant effect of IWR was observed on the ovarian granulosa cell proliferation. No significant difference in the oestradiol levels was found in the spent media harvested after six days of in vitro culture among different groups in small and large-sized ovarian follicles. However, the oestradiol level varied significantly (p < .05) among different treatment groups in medium-sized follicles. The oestradiol level was significantly lower (p < .05) in IWR group compared with the control group and was also significantly lower in IWR + FSH group compared with the FSH group. The Wnt inhibitor had significantly (p < .05) reduced the gene expression of CYP19A1 in large ovarian follicles. Varied effects of IWR-1 and FSH on the expression of other genes were observed. The results indicated that there is a positive role of Wnt signal in oestradiol synthesis in buffalo, but the positive role was more discernible in medium- and large-sized follicles.

Copper and Selenium stimulates CYP19A1 expression in caprine ovarian granulosa cells: possible involvement of AKT and WNT signalling pathways.

The role of copper and selenium on activation of estradiol synthesis pathways viz. PKA/AKT/WNT is not clearly elucidated. On this background we attempt to elcuiated the role of copper and selenium on mRNA expression of genes associated with estradiol synthesis in caprine ovarian granulose cell models. Ovarian granulosa cells from medium (3-5 mm) sized follicles were aspirated and distributed separately to different groups. Group I: control, Group II: cupric chloride (Cu: 0.5 mM), Group III: sodium selenite (Se: 100 ng/ml), Group IV: Cu + Se. The cells (105/well) were cultured in 96 well plate in the base culture medium of MEMα comprising of nonessential amino acids (1.1 mM), FSH (10 ng/mL), transferrin (5 µg/mL), IGF-I (2 ng/mL), androstenedione (10-6 M), penicillin (100 IU/mL), streptomycin (0.1 mg/mL) and fungizone (0.625 µl/mL) and insulin (1 ng/mL). The cells were incubated in a carbondioxide incubator (38 °C, 5% CO2, 95% RH). The medium was changed on alternate days and cells were harvested on day 6. Day 6 media was used for estimation of estradiol. The RNA isolated form harvested cells was used for qPCR assay. There was no significant (p > 0.05) difference in estradiol concentration between groups. The mRNA expression of AKT1, CYP19A1, WNT2 & 4, FZD6 and APC2 were significantly (p < 0.05) higher in Cu and Cu + Se groups compared to control. Whereas, the mRNA transcript of DVL1 and CSNK1 was significantly (p < 0.05) higher in Cu + Se group compared to control. Incontrast, no significant difference in mRNA expression of PRKAR1A and CTNNB1 was noticed. Our study support a key role of copper and selenium in activation of AKT and WNT signalling pathway that further lead to increase in the mRNA expression of CYP19A1.