Iturin A Rescued STb-R-Induced Pork Skeletal Muscle Growth Restriction through the Hypothalamic-Pituitary-mTORC1 Growth Axis

Abstract

The engineered STb-Rosetta Escherichia coli (STb-R) was designed to investigate the effects of Iturin A on the skeletal muscle growth of weaned piglets. A total of 28 piglets were randomly divided into 4 groups (7 piglets per group): the control group (100 mL PBS), the Iturin A group (100 mL 320 mg/kg body weight (BW) Iturin A), the STb-R group (100 mL 1 × 1010 CFU/mL STb-R), and the Iturin A + STb-R group (100 mL 320 mg/kg BW Iturin A + 1 × 1010 CFU/mL STb-R). Compared with the control, STb-R-reduced body weight gain were rescued by Iturin A. The semimembranosus muscle weight recovered to normal level in the Iturin A + STb-R group. The level of relevant genes of the growth axis were elevated by Iturin A, including GHRH in the hypothalamus, GHRHR and GH in the pituitary, and GHR, IGF-1 and IGF-1R in the semimembranosus muscle. Moreover, Iturin A increased the mean fiber area and the number of proliferating cells in the semimembranosus muscle, which were decreased by STb-R. Additionally, the mTORC1 pathway was reactivated by Iturin A to relieve the suppression of STb-R. Collectively, the hypothalamic-pituitary growth axis-mediated Iturin A reactivated the mTORC1 pathway to rescue STb-R-restricted pork skeletal muscle growth.

Chemical composition of pigeon crop milk and factors affecting its production: a review

“…Studies have indicated that insulin can bind to insulin receptors, and that phosphorylated insulin receptor substrate 1 ( IRS1 ) regulates protein synthesis in skeletal muscle satellite cells and in the breast tissue of dairy cows by activating signaling pathways such as protein kinase B-target of rapamycin complex 1 ( Akt-TORC1 ; Bolster et al, 2004 ; Yang et al, 2015 ; Xie et al, 2021 ; Ye et al, 2022 ). Our previous study showed that the serum prolactin and insulin contents in lactating pigeons were significantly higher than those in nonbreeding pigeons, and the phosphorylated protein levels of IRS1, Akt, TOR, ribosomal protein S6 kinase 1 ( S6K1 ), ribosomal protein S6 ( S6 ), eukaryotic initiation factor 4E binding protein 1 ( 4EBP1 ), and eukaryotic initiation factor 4E ( eIF4E ) were all upregulated during lactation ( Hu et al, 2016 ).…”