Inhibition of ∆9-desaturase activity with sterculic acid: effect on the endogenous synthesis of cis-9 18:1 and cis-9, trans-11 18:2 in dairy sheep.
This study was conducted in lactating ewes to examine the involvement of ∆(9)-desaturase in mammary lipogenesis, especially in the endogenous synthesis of cis-9, trans-11 18:2 and cis-9 18:1, because no information on this matter was available for dairy sheep. With this aim, 6 Assaf ewes were monitored in a 15-d experiment, which included a 5-d pretreatment period, a 5-d treatment period, and a 5-d posttreatment period. During the treatment period, ewes received 0.5 g/d of sterculic acid (a cyclopropene fatty acid that inhibits ∆(9)-desaturase), delivered intravenously in 4 equal doses at 6-h intervals. Animals were fed pasture to supply mainly α-linolenic acid and minimize the amount of milk cis-9, trans-11 18:2 of ruminal origin. Sterculic acid administration was calculated to inhibit ∆(9)-desaturase by 70% based on the milk content of cis-9 14:1. This inhibition resulted in decreases in the milk content of the enzyme products (e.g., cis-9 10:1, cis-9 14:1, cis-9 16:1, cis-9 18:1, and cis-9, trans-11 18:2) and increases in its substrates (e.g., 14:0, 18:0, and trans-11 18:1), as well as in reductions in the desaturase indexes. Some other milk fatty acids, further to previously reported products or substrates of ∆(9)-desaturase (e.g., cis-15 18:1 and cis-9, cis-15 18:2, or trans-11, trans-15 18:2, and cis-9, trans-11, trans-15 18:3), were also affected by sterculic acid administration. Endogenous synthesis was the major source of cis-9 18:1 and cis-9, trans-11 18:2, accounting for 63 and 74% of its content in milk fat, respectively. To our knowledge, the present study provides the first estimates of endogenous synthesis of these 2 bioactive fatty acids in ovine milk fat.
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n. 24346 Grulleros, León, Spain.
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Bichi
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n. 24346 Grulleros, León, Spain.
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Toral
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n. 24346 Grulleros, León, Spain.
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Hervás
Instituto de Ganadería de Montaña (CSIC-ULE), Finca Marzanas s/n. 24346 Grulleros, León, Spain.
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Frutos
Instituto de Investigación en Ciencias de la Alimentación (CSIC-UAM), Nicolás Cabrera, 9. Campus de Cantoblanco, 28049 Madrid, Spain.
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Gómez-Cortés
Instituto de Investigación en Ciencias de la Alimentación (CSIC-UAM), Nicolás Cabrera, 9. Campus de Cantoblanco, 28049 Madrid, Spain.
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Juárez
Instituto de Investigación en Ciencias de la Alimentación (CSIC-UAM), Nicolás Cabrera, 9. Campus de Cantoblanco, 28049 Madrid, Spain. Electronic address: mafl@if.csic.es.
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de la Fuente
D000818:Animals; D003521:Cyclopropanes / Q000494:pharmacology*; D005227:Fatty Acids / Q000032:analysis / Q000096:biosynthesis*; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D005260:Female; D007774:Lactation / Q000187:drug effects / Q000502:physiology; D044243:Linoleic Acids, Conjugated / Q000032:analysis / Q000096:biosynthesis*; D008892:Milk / Q000737:chemistry; D012756:Sheep; D013230:Stearoyl-CoA Desaturase / Q000037:antagonists & inhibitors*
D003521:Cyclopropanes; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D044243:Linoleic Acids, Conjugated; D013230:Stearoyl-CoA Desaturase; C003345:sterculic acid