Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The object of this study was to investigate the effect of maternal metabolic state on the activity of lipoprotein lipase (LPL) in human milk. Although the total LPL activity in milk was not significantly affected by up to three cycles of freezing and thawing, the amount of LPL associated with the cream fraction of the milk increased from an average of less than 10% to about 70% after this treatment. The enzyme was relatively stable when the milk was stored on ice, losing activity at a rate of about 1% per hour. At 37 degrees C degradation was more rapid, about 7% per hour. When LPL activity was measured in samples taken at hourly intervals by breast pump, using oxytocin to achieve a complete letdown at each pumping, activity was found to double from the first to the third pumping. Thereafter the activity was stable under fasting conditions. Hyperglycemic and euglycemic, hyperinsulinemic glucose clamp protocols were used to evaluate the effects of glucose and insulin. Both high plasma glucose and high plasma insulin in the presence of normal glucose significantly increased LPL activity within 4 hours. We conclude that, like adipose, tissue LPL, mammary LPL is regulated by plasma insulin.
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PMID:Lipoprotein lipase in human milk: compartmentalization and effect of fasting, insulin, and glucose. 206 61

The ability of lipoprotein lipase to move across the mammary epithelium by a paracellular route was investigated. Five goats were milked hourly to activate the paracellular pathway. Three goats responded to hourly milking with a fivefold increase in milk lipoprotein lipase activity as compared with nonresponding goats. Massage of the mammary gland was necessary in the two nonresponding goats too cause increased lipoprotein lipase activity in milk. Oxytocin treatment during hourly milking also increased enzyme activity in milk from a nonresponding goat. Activation of the paracellular pathway by hourly milking increased milk sodium and protein and decreased potassium and lactose concentrations. After a 12-h milking interval, lipoprotein lipase activity was distributed primarily in the serum (48%) and cream (40%) fractions and, to a lesser extent, in the casein (12%) fraction. Hourly milking increased enzyme activity distributed in the serum fraction (62%), whereas enzyme activity associated with the cream (32%) and casein (6%) fractions decreased. Possible mechanisms for the origin of lipoprotein lipase in milk are discussed.
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PMID:Paracellular leakage of lipoprotein lipase across the mammary epithelium of the goat. 274 24

Milk yield declined significantly between days 22 and 28 of lactation in rats, when lactation was extended by frequent replacement of older litters with younger ones. Corticosterone implants but not cortisol injections or implants prevented this decline. Cortisol, however, appeared to inhibit milk ejection since the mammary glands became engorged with milk and milk yield was improved dramatically by oxytocin injections. In both cases corticosteroid concentrations increased approximately threefold above basal concentrations. Both corticosteroids increased total mammary gland RNA content and lipoprotein lipase (LPL) activity of the mammary gland but were without effect on insulin binding. They also decreased LPL activity, lipogenesis and the number of insulin receptors on adipose tissue. Serum prolactin and insulin concentrations were unaffected by any of the treatments. The results suggest that corticosteroids inhibit milk ejection under certain conditions, may be circulating in lower concentrations, which thereby limit milk production, during prolonged lactation and may improve milk yield during extended lactation in part by suppressing anabolic activity in adipose tissue.
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PMID:Stimulation of milk secretion with inhibition of milk ejection by corticosteroids during extended lactation in the rat. 649 78