2 Intrafollicular injection of asprosin in water buffaloes and the potential role of FBN1 mRNA and asprosin in follicular function

Fibrillin-1 (FBN1) functions as a structural protein in the ovary, whereas the role of its protein product asprosin remains unknown. Both proteins are encoded by the FBN1 gene; when it is cleaved at the C-terminal end, asprosin is produced. Asprosin acts as an orexigenic hormone and is associated with various metabolic parameters and sex related hormones in women. One goal of this research was to quantify FBN1 and the presumed asprosin receptor, olfactory receptor family 4 subfamily M member 1 (OR4M1) mRNA in water buffalo granulosa cells (GC) and correlate them to aromatase (CYP19A1) gene expression. A second goal was to determine the effect of asprosin on follicular growth invivo. In Experiment 1, ovaries were collected from a local slaughterhouse, GC from small (  0.10). Abundance of CYP19A1 mRNA was positively correlated with FBN1 (r = 0.55, P < 0.05) and OR4M1 mRNA (r = 0.50, P < 0.05). In Experiment 2, there was a treatment × day interaction (P < 0.10) for follicle size and growth rate of follicles. Cows treated with asprosin had a higher growth rate from Day 1 to 2 (1.09 ± 0.39 to 2.37 ± 0.32 mm/day) than placebo cows (1.74 ± 0.55 to 1.05 ± 0.61 mm/day) after injection. Most of the follicles from both treatment groups ovulated 3 days post injection. These findings suggest that FBN1 (and thus asprosin) are present in buffalo GC and may be developmentally expressed. Also, asprosin may induce follicular growth when given invivo. Whether these proteins directly regulate aromatase expression, and therefore oestradiol production, during follicle development will require further study.