Metformin Prevents Follicular Atresia in Aging Laying Chickens through Activation of PI3K/AKT and Calcium Signaling Pathways

Abstract

Increased follicular atresia occurs with aging and results in reduced fecundity in laying chickens. Therefore, relieving follicular atresia of aging poultry is a crucial measure to maintain sustained high laying performance. As an antiaging agent, metformin was reported to play important roles in preventing aging in diverse animals. In this study, the physiological state of the prehierarchical follicles in the peak-laying hens (D280) and aged hens (D580) was compared, followed with exploration for the possible capacity of metformin in delaying atresia of the prehierarchical follicles in the aged D580 hens. Results showed that the capacity of yolk deposition within follicles declined with aging, and the point of endoplasmic reticulum- (ER-) mitochondrion contact decreased in the ultrastructure of the follicular cells. Meanwhile, the expression of apoptosis signaling genes was increased in the atretic small white follicles. Subsequently, the H2O2-induced follicular atresia model was established to evaluate the enhancing capacity of metformin on yolk deposition and inhibition of apoptosis in the atretic small white follicles. Metformin inhibited apoptosis through regulating cooperation of the mitochondrion-associated ER membranes and the insulin (PI3K/AKT) signaling pathway. Furthermore, metformin regulated calcium ion homeostasis to relieve ER-stress and inhibited release of mitochondrion apoptosis factors (BAD and caspase). Additionally, metformin activated PI3K/AKT that suppressed activation of BAD (downstream of the insulin signaling pathway) in the atretic follicles. Further, serum estrogen level and liver estrogen receptor-α expression were increased after dietary metformin supplementation in D580 hens. These results indicated that administration of dietary metformin activated the PI3K/AKT and calcium signaling pathway and enhanced yolk deposition to prevent chicken follicular atresia.

Protective Effect of Grape Seed Proanthocyanidins on Oxidative Damage of Chicken Follicular Granulosa Cells by Inhibiting FoxO1-Mediated Autophagy

“…Using H&E staining, we observed the structure of the D580 chicken ovarian tissues was damaged and the SWFs displayed a loose and irregular arrangement of the granulosa cells, which was consistent with the previous studies ( Liu X. T. et al, 2018 ; Yao et al, 2020 ). The TEM observation verified that the accumulation of autophagic vesicle in the cytoplasm and such accumulation appeared in D580 chicken SWFs.…”

“…For senescence induction, a modified H 2 O 2 treatment protocol was used ( Yao et al, 2020 ). Briefly, the cultured GCs from D280 hens SYFs were treated with H 2 O 2 in a gradient concentrations from 50 to 150 μM to induce oxidative damage.…”

“…In poultry production, it’s extremely important to develop attenuating measures to effectively prevent advanced ovarian aging to extend the laying period. Numerous plant-derived natural compounds or synthesized chemicals have been evaluated for their effects in preventing ovarian aging, thus enhancing the poultry laying performance ( Yao et al, 2020 ). In recent years, some natural compounds with antioxidant capacities, such as melatonin ( Ming et al, 2018 ), lycopene ( Liu X. et al, 2018 ), and aloe-emodin ( Lu et al, 2007 ), have been widely studied to postpone aging.…”

Understanding Transcriptomic and Serological Differences between Forced Molting and Natural Molting in Laying Hens

“…The ovarian DEGs in the FM_2-vs-NM_2 group were mainly enriched process connected with immune (cell adhesion, regulation of inflammatory response, single organismal cell-cell adhesion, substrate adhesion-dependent cell spreading, immune response and Salmonella infection), development (lung development, liver development, kidney development, osteoblast development, and cardiovascular system development), aging (Vitamin B6 metabolism, branching morphogenesis of an epithelial tube, and positive regulation of endothelial cell migration) and reproduction (calcium ion binding, Calcium signaling pathway, and GnRH signaling pathway). The calcium signaling pathway does not only regulate the animal endocrine system, development, proliferation, metabolism, and smooth muscle formation [ 42 ], but also promotes the enhancement of egg laying performance in aged chickens [ 43 ]. The GnRH signaling pathway is associated with egg production traits in chickens [ 12 ].…”

Naringin prevents follicular atresia by inhibiting oxidative stress in the aging chicken

“…Single SWF from D280 and D580 hens was cultured in the complete Dulbecco's Modified Eagle's Medium (Hyclone, Tauranga, New Zealand) with 10 µg/mL insulin, 5 μg/mL transferrin, 30 nM selenite ( ITS , Sigma-Aldrich, St. Louis, MO), 100 IU/mL penicillin, 100 μg/mL streptomycin, and 5% fetal calf serum ( FCS , Hyclone, UT) at 38.5°C and 5% CO 2 for 96 h (D280) or 72 h (D580). The media were renewed every 24 h. For the 5-bromo-20-deoxyuridine ( BrdU ) incorporation test, the follicles were incubated with complete medium supplemented with 10 μg/mL BrdU (Sigma-Aldrich) at the last 24 h. 1) For the culture of D280 SWFs in vitro, firstly, to screen the optimal concentration of naringin (Shanghai Yuanye Bio-Technology Co., Ltd.), different concentrations of naringin (0, 0.05, 0.5, and 5 mM) were used to pre-treat for 24 h. Then, 1 mM H 2 O 2 (Sinopharm Chemical Reagent Co., Ltd, Shanghai, China) was added and incubated for 72 h to establish a model of atretic small white follicles ( ASWFs ) ( Yao et al., 2020 ). 2) Afterwards, the optimal concentration of naringin treatment was selected based on histomorphology, cell proliferation, and cell apoptosis.…”