Insulin regulation of amino-acid metabolism in the mammary gland of sheep in early lactation and fed fresh forage

Sinclair, B. R.; Back, P. J.; Davis, Stephen R.; Lee, J.; Mackenzie, D. D. S.; McNabb, Warren C.; Roy, Nicole C.; Tavendale, Michael H.; Harris, Patricia M.

doi:10.1017/s1751731109004157

Cited by 4 publications

(1 citation statement)

References 34 publications

(58 reference statements)

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“…Insulin plays an important role in regulating the distribution of nutrients in ruminants during lactation [ 106 ]. Plasma insulin levels also affect the milk yield of ruminants; namely, low insulin levels are correlated with higher milk production [ 107 ].…”

Section: The Importance Of Vitamins and Hormonesmentioning

confidence: 99%

Importance of Bioactive Substances in Sheep’s Milk in Human Health

Flis

Molik

2021

IJMS

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Sheep’s milk is an important source of bioactive substances that have health-promoting functions for the body. The valuable composition of sheep’s milk is due to the high content of fatty acids, immunoglobulins, proteins, hormones, vitamins and minerals. Many biopeptides found in milk have antibacterial, antiviral and anti-inflammatory properties. The bioactive substances of sheep’s milk also show anticancer properties. Sheep’s milk, thanks to its content of CLA and orotic acid, prevents the occurrence of type 2 diabetes, Alzheimer’s disease and cancer. Sheep’s milk, as a product rich in bioactive substances, can be used as a medical aid to support the body in the fight against neurological and cancer diseases.

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Section: The Importance Of Vitamins and Hormonesmentioning

confidence: 99%

Importance of Bioactive Substances in Sheep’s Milk in Human Health

Flis

Molik

2021

IJMS

View full text Add to dashboard Cite

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Hormonal regulation of leucine catabolism in mammary epithelial cells

et al. 2012

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Branched-chain amino acids (BCAA) are actively taken up and catabolized by the mammary gland during lactation for syntheses of glutamate, glutamine and aspartate. Available evidence shows that the onset of lactation is associated with increases in circulating levels of cortisol, prolactin and glucagon, but decreases in insulin and growth hormone. This study determined the effects of physiological concentrations of these hormones on the catabolism of leucine (a representative BCAA) in bovine mammary epithelial cells. Cells were incubated at 37 °C for 2 h in Krebs buffer containing 3 mM D-glucose, 0.5 mM L-leucine, L-[1-14C]leucine or L-[U-14C]leucine, and 0-50 μU/mL insulin, 0-20 ng/mL growth hormone 0-200 ng/mL prolactin, 0-150 nM cortisol or 0-300 pg/mL glucagon. Increasing extracellular concentrations of insulin did not affect leucine transamination or oxidative decarboxylation, but decreased the rate of oxidation of leucine carbons 2-6. Elevated levels of growth hormone dose dependently inhibited leucine catabolism, α-ketoisocaproate (KIC) production and the syntheses of glutamate plus glutamine. In contrast, cortisol and glucagon increased leucine transamination, leucine oxidative decarboxylation, KIC production, the oxidation of leucine 2-6 carbons and the syntheses of glutamate plus glutamine. Prolactin did not affect leucine catabolism in the cells. The changes in leucine degradation were consistent with alterations in abundances of BCAA transaminase and phosphorylated levels of branched-chain α-ketoacid dehydrogenase. Reductions in insulin and growth hormone but increases in cortisol and glucagon with lactation act in concert to stimulate BCAA catabolism for glutamate and glutamine syntheses. These coordinated changes in hormones may facilitate milk production in lactating mammals.

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