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The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens.

ABSTRACT: The molecular mechanisms underlying reproductive aging in avian species are poorly understood. Previous studies have shown the importance of mechanistic target of rapamycin (mTOR) signaling pathway in aging. In this study, we investigated the relationship between the mTOR signaling pathway and ovarian aging in the peak phase and late phase of egg production in laying hens. The egg production rate and egg quality were tracked for 5 consecutive weeks in 30-week-old and 70-week-old Dawu Jinfeng hens (N = 30/group). During the peak phase (week 35) and late phase (week 75), antioxidant and immune indicators were detected by enzyme-linked immunosorbent assay, and mTOR signaling-related genes (CLIP-170, GRB10, LIPIN-1, ATG1, 4E-BP1, S6K, PKC, RHO, and SGK1) were detected in the follicles by quantitative reverse transcription-PCR technology. The protein expression of key genes (mTOR, PKC, 4EBP1) was evaluated by Western blot analysis. The egg production rate and the antioxidant indexes superoxide dismutase and glutathione peroxidase and the levels of total antioxidant capacity and immunoglobulins (IgM and IgG) were significantly higher at week 35 than those at week 75 (P < 0.01), while malondialdehyde levels were significantly lower (P < 0.01). At week 75, there were fewer follicles in the different stages of development than were detected at week 35. The number of white follicles (large and small) and primary follicles were significantly higher at week 75 than those detected at week 35 (P < 0.01). The mRNA expression of avTOR, CLIP-170, GRB10, LIPIN-1, 4E-BP1, S6K, RHO, and SGK genes in small white follicles (SWF), large white follicles (LWF), F3, F1, and ovary at week 75 was lower than that in the hens at week 35 (P < 0.05). The mRNA expression in small yellow follicle (SYF) was significantly higher than that at week 35 (P < 0.05), while the mRNA expression of ULK1 in SWF, LWF, F3, F1, and ovary at week 75 was higher than that of hens at week 35 (P?0.01), and SYF was lower (P < 0.05). Treatment of chicken granulosa cells with the mTOR agonist MHY1485 significantly enhanced granulocyte proliferation (P < 0.01) and inhibited apoptosis (P < 0.01) and significantly increased avTOR, S6K, 4E-BP1, and PKC gene expression (P < 0.01). The protein expression levels of mTOR, S6K, p-mTOR, and p-S6K were consistent with mRNA expression levels. The mTOR activity is age-specific, and a compensatory enhancement of the mTOR signaling cascade can regulate ovarian follicular development in aged laying hens.

SUBMITTER: Hao EY

PROVIDER: S-EPMC7772700 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens.

Hao Er-Ying EY Wang De-He DH Chen Yi-Fan YF Zhou Rong-Yan RY Chen Hui H Huang Ren-Lu RL

Poultry science 20201012 1

The molecular mechanisms underlying reproductive aging in avian species are poorly understood. Previous studies have shown the importance of mechanistic target of rapamycin (mTOR) signaling pathway in aging. In this study, we investigated the relationship between the mTOR signaling pathway and ovarian aging in the peak phase and late phase of egg production in laying hens. The egg production rate and egg quality were tracked for 5 consecutive weeks in 30-week-old and 70-week-old Dawu Jinfeng hen ...[more]

PMID: 33357698

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Project description:The intense selection of chickens for production traits, such as egg laying, is thought to cause undesirable side effects and changes in behavior. Trade-offs resulting from energy expenditure in productivity may influence other traits: in order to sustain energetic costs for high egg production, energy expenditure may be redirected away from specific behavioral traits. For example, such energetic trade-offs may change the hens' cognitive abilities. Therefore, we hypothesized highly productive laying hens to show reduced learning performance in comparison to moderate productive lines. We examined the learning ability of four chicken lines that differed in laying performance (200 versus 300 eggs/year) and phylogenetic origin (brown/white layer; respectively, within performance). In total 61 hens were tested in semi-automated Skinner boxes in a three-phase learning paradigm (initial learning, reversal learning, extinction). To measure the hens' learning performance within each phase, we compared the number of active decisions needed to fulfill a learning criteria (80% correct choices for learning, 70% no responses at extinction) using linear models. Differences between the proportions of hens per line that reached criterion on each phase of the learning tasks were analyzed by using a Kaplan-Meier (KM) survival analysis. A greater proportion of high productive hens achieved the learning criteria on each phase compared to less productive hens (Chi2 3 = 8.25, p = 0.041). Furthermore, high productive hens accomplished the learning criteria after fewer active decisions in the initial phase (p = 0.012) and in extinction (p = 0.004) compared to the less selected lines. Phylogenetic origin was associated with differences in learning in extinction. Our results contradict our hypothesis and indicate that the selection for productivity traits has led to changes in learning behavior and the high productive laying hens possessed a better learning strategy compared to moderate productive hens in a feeding-rewarding context. This better performance may be a response to constraints resulting from high selection as it may enable these hens to efficiently acquire additional energy resources. Underlying mechanisms for this may be directly related to differences in neuronal structure or indirectly to foraging strategies and changes in personality traits such as fearfulness and sociality.

Dataset Information

The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens.

Publications

The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens.

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