A Transcriptome Approach Evaluating the Effects of Atractylenolide I on the Secretion of Estradiol and Progesterone in Feline Ovarian Granulosa Cells

Atractylodes macrocephala Koidz (AMK) as an oriental medicine has been used in the treatment of threatened abortion. Atractylenolide I (AT-I) is one of the major bioactive components of AMK. This study aimed to investigate the effect of AT-I on the secretion of estradiol (E₂) and progesterone (P₄) in feline ovarian granulosa cells (FOGCs), which is necessary for pregnancy. At first, the proliferation of FOGCs after AT-I treatment was measured by CCK-8. Then, the synthesis of E₂ and P₄ were measured by ELISA. Lastly, transcriptome sequencing was used to detect the DEGs in the FOGCs, and RNA-seq results were verified by RT-qPCR and biochemical verification. It was found that AT-I could promote proliferation and the secretion of E₂ and P₄ in FOGCs; after AT-I treatment, 137 significant DEGs were observed, out of which 49 were up-regulated and 88 down-regulated. The DEGs revealed significant enrichment of 52 GO terms throughout the differentiation process (p < 0.05), as deciphered by Gene Ontology enrichment analysis. Kyoto Encyclopedia of Genes and Genomes analysis manifested that the DEGs were successfully annotated as members of 155 pathways, with 23 significantly enriched (p < 0.05). A relatively high number of genes were enriched for the cholesterol metabolism, ovarian steroidogenesis, and biosynthesis of unsaturated fatty acids. Furthermore, the contents of the total cholesterol and low-density lipoprotein cholesterol were decreased by AT-I treatment in the cell culture supernatant. The results indicated that AT-I could increase the ability of FOGCs to secrete E₂ and P₄, which might be achieved by activation of cholesterol metabolism.