Glycerol Supplementation During Oestrus Synchronisation With Fluorogestone Acetate Affects Follicular Proliferation, Maturation and Apoptosis of Granulosa Cells in Pelibuey Ewes

This study investigated the impact of glycerol supplementation on the expression of markers associated with follicular proliferation, maturation and apoptosis in Pelibuey ewes synchronised with long (11 days) and short (5 days) protocols using intravaginal fluorogestone acetate (FGA). Forty-five adult Pelibuey ewes were divided into five groups: control, short protocol with or without glycerol and long protocol with or without glycerol. Follicular dynamics were monitored by ultrasonography, and granulosa cells were collected 15 h after the onset of oestrus to analyse gene expression using RT-qPCR of genes associated with proliferation, maturation, and apoptosis. Results indicated that glycerol supplementation or the duration of the synchronisation protocol influenced the expression of genes related to apoptosis, proliferation and maturation. Specifically, glycerol-treated groups exhibited decreased BCL2 expression, and the ratio BCL2/BAX was lower in all treatment groups compared to the control, particularly in the short protocol plus glycerol. We conclude that the use of glycerol as an ultrashort supplementation during different synchronisation protocols leads to a delay in maturation and induces apoptotic-related pathways in granulosa cells to granulosa cell likely reducing the oocyte viability. Finally, glycerol treatment does not increase the abundance of PCNA associated with granulosa cell proliferation. However, it is observed that short-term treatments promote proliferation compared to the control group.