Sexual Maturity Promotes Yolk Precursor Synthesis and Follicle Development in Hens via Liver-Blood-Ovary Signal Axis

Abstract

Several reproductive hormones were reported to be involved in regulating egg yolk precursor synthesis in chickens; however, the mechanism that shows how the liver-blood-ovary signal axis works in relation to age changes has not been reported yet. Therefore, in this study, we observe the morphology and histology of the liver and ovary and determine the serum biochemical parameters and the expression abundance of the critical genes from d90 to 153. Results show that the body weight and liver weight were significantly increased from d132, while the ovary weight increased from d139. Aside from the increase in weight, other distinct changes such as the liver color and an increased deposition of large amounts of yolk precursors into the ovarian follicles were observed. On d139, we observed small fatty vacuoles in the hepatocytes. The results of serum biochemical parameters showed a significant increase in the estradiol (E2) level, first on d125, and then it reached its peak on d132. Meanwhile, the levels of follicle-stimulating hormone (FSH) increased initially and then remained at a high level from d146 to d153, while the levels of luteinizing hormone (LH) increased significantly on d132 and reached the top level on d153. Moreover, the levels of lecithin (LEC), vitellogenin (VTG), very low density lipoprotein y (VLDLy), triglyceride (TG), and total cholesterol (TC) were significantly increased at d125 and were close from d146 to d153. The mRNA and protein expression of estrogen receptor-alpha (ER-α) and E2 levels in the liver and serum, respectively, showed similar changes. Moreover, with reference to an increase in serum E2 level, the mRNA expression of genes related to yolk precursor synthesis (very low density apolipoprotein-II, ApoVLDL-II) and vitellogenin-II (VTG-II), lipogenesis (fatty acid synthase, FAS), and lipid transport (microsomal triglyceride transport protein, MTTP) in the liver showed up-regulation. These results suggest that the correlation between liver-blood-ovary alliances regulate the transport and exchange of synthetic substances to ensure synchronous development and functional coordination between the liver and ovary. We also found that E2 is an activator that is regulated by FSH, which induces histological and functional changes in the hepatocytes through the ER-α pathway.

Synergistic effects of quercetin and vitamin E on egg production, egg quality, and immunity in aging breeder hens

“…It has been well documented that flavonoids, including quercetin (a phytoestrogenic compound) exert agonistic and antagonistic effects depending on the intrinsic estrogen concentration ( Cassidy, 2003 ; Yang and Chaudhry, 2018 ; Amevor et al., 2021 ). This is because estradiol ( E 2 ) actively facilitates the production and function of other reproductive hormones, including follicle stimulating hormone ( FSH ) in sexually mature hens ( Liu et al., 2018 ; Cui et al., 2020 ). The results of this study first showed the potential of the combination of quercetin and vitamin E to improve the laying rate and decrease the feed-egg ratio in aging laying hens.…”

“…This may be due to the decline in reproductive potentials including vitellogenesis, lipogenesis, and antioxidant and immune status of the breeder chickens, and of course also due to management, environment, nutrition, genetics, or the combined effect of these factors ( Joyner et al., 1987 ; Durape, 2007 ; Liu et al., 2013 ; Liu et al., 2018 ). Recently, our study revealed that sexual maturity promotes yolk precursor synthesis and follicle development in breeder hens via the liver-blood-ovary signal axis, which regulates the transport and exchange of synthetic substances, including yolk precursors and reproductive hormones (e.g., estradiol) to ensure synchronous development and functional coordination between the liver and ovary to promote egg production in breeder hens ( Cui et al., 2020 ).…”

Supplementation of Dietary Quercetin and Vitamin E Promotes the Intestinal Structure and Immune Barrier Integrity in Aged Breeder Hens

“…Total RNA was extracted from the intestinal (duodenum, jejunum, and ileum) mucosal scrapings following previously described procedures ( 27 , 28 , 60 ), using TRIzol reagent (Takara, Dalian, China), according to the manufacturer’s instructions. Then, the concentration and purity of the extracted RNA were determined using Nanodrop 2000C (Thermo Fisher Scientific, Waltham, MA, USA) with an absorbance ratio of A260/280.…”

Plasma metabolomic profiling reveals potential onset of lay biomarkers in broiler breeders

“…Production of phosphatidylcholine metabolites might have been upregulated to be used as the precursors of egg yolk when a hen matures and commences egg laying. Cui et al. (2020) demonstrated that as Rohman layer pullets approached sexual maturity from 125 d onward, reproductive hormonal changes (mainly estrogen) directly increased the expression of genes related to lipogenesis (fatty acid synthase) and yolk precursor (very low density apolipoprotein-II and vitellogenin-II) synthesis, which increased serum concentration of phospholipid, triacylglycerol, vitellogenin, very low density lipoprotein y ( VLDLy ), lecithin, total cholesterol, and triglyceride.…”