Effects of quercetin on granulosa cells from prehierarchical follicles by modulating MAPK signaling pathway in chicken

Quercetin (Que), widely found in a huge variety of plants, plays important roles in ovarian func-tion. However, to data, there have been no reports about Que regulating granulosa cells (GCs) in prehierarchical follicles in chicken. Herein, GCs from follicles diameter from 4 to 8 mm in chicken were treated by Que in vitro culture to investigate how Que exerts its effect on follicu-lar development. GCs treated by Que in concentrations of 10, 100, and 1,000 ng/mL were tested for cell prolifer-ation and progesterone secretion. Eight cDNA libraries were constructed from GCs (4 samples per group) to explore transcriptome expression changes. The role of the MAPK/ERK signaling pathway was validated in this process. Treatment with 100 and 1,000 ng/mL levels of Que significantly promoted cell proliferation and progesterone secretion (P < 0.05). RNA-seq analysis data showed that 402 and 263 differentially expressed genes (DEGs) were up-and down-regulated, respec-tively. Functional enrichment analysis that the path-ways related to follicular development included biosynthesis of amino acids, MAPK signaling pathway, and calcium signaling pathway. Notably, the function exerted in GCs of the different levels of Que was associ-ated with the suppression of the MAPK pathway. In conclusion, our results proved that low levels of Que could promote MAPK signaling pathway, but high lev-els of Que inhibit MAPK signaling pathway in GCs from the prehierarchical follicles, promote cell prolifera-tion and progesterone secretion, and benefit follicle selection.