Gene expression profiles in the oocyte and granulosa cells and concomitant follicular fluid steroid hormone concentrations in pregnant versus non-pregnant she-camels

Abstract

• Pregnancy induces variations in the number of growing follicles on the ovary. • Pregnancy induces different variations in gene expression in the oocyte. • Pregnancy induces different variations in gene expression in granulosa cells (GCs). • Pregnancy induces different variations in the progesterone (P4) and estradiol (E2) levels in the follicular fluid. A total of 138 pairs of slaughterhouse ovaries were collected from pregnant (n = 46) and non-pregnant (n = 92) she-camels. Oocytes (n = 150) and related granulosa cells (GCs) were retrieved from the growing follicles (3–8 mm) to study the effect of pregnancy status on the expression pattern of genes regulating follicles population and follicular fluid (FF) levels of estrogen (E2) and progesterone (P4). The mRNA fold changes of STAR, PTEN, and BCL2 genes were greater (p < 0.001) in the GCs of pregnant vs. non-pregnant she-camels and in the oocytes of non-pregnant vs. pregnant she-camels. The mRNA fold change of IGF1 was higher in the GCs of pregnant vs. non-pregnant (p < 0.05) and in the oocytes of non-pregnant vs. pregnant (p < 0.01) she-camels. Although the mRNA fold changes of both BMP15 and STAT1 in the GCs did not differ between pregnant and non-pregnant, they were greater (p < 0.001) in the oocytes of non-pregnant vs. pregnant she-camels. The mRNA fold change of FOS was greater (p < 0.001) in both oocytes and GCs of pregnant vs. non-pregnant she-camels. The follicles population was smaller (p < 0.05), and the FF level of P4 was higher (p < 0.0001) in the pregnant vs. non-pregnant she-camels. The higher expression level of FOS (activator protein transcription factor) in both GCs and oocytes and lower expression level of STAT1 (activated signal transducer and activator of transcription) in the pregnant relative to non-pregnant she-camels could regulate the expression levels of other studied genes, thereby regulating the growing follicles population and their follicular fluid P4 concentration. Further studies are needed to investigate the interaction between the expression levels of both FOS and/or STAT1 (signaling pathways) and other candidate genes.