Synthesis of long-chain polyunsaturated fatty acids in lactating mammary gland: role of [Delta]5 and [Delta]6 desaturases, SREBP-1, PPAR[alpha], and PGC-1
2006
Rodriguez-Cruz, Maricela | Tovar, Armando R. | Palacios González, Berenice | Prado, Martha del | Torres, Nimbe
The purpose of this work was to study whether rat lactating mammary gland can synthesize PUFAs through the expression of [Delta]5 and [Delta]6 desaturases ([Delta]5D and [Delta]6D), whether these enzymes are regulated by the transcription factors sterol-regulatory element binding protein 1 (SREBP-1) and peroxisome proliferator-activated receptor [alpha] (PPAR[alpha]) and the coactivator peroxisome proliferator-activated receptor [gamma] coactivator 1{szligbeta} (PGC-1{szligbeta}), and whether these desaturases are regulated by the lipid concentration in the diet. The results showed that on day 12 of lactation, [approximately]35% of the linoleic acid in the diet, which is the precursor of PUFAs, is transferred to the mammary gland. There was expression of [Delta]5D and [Delta]6D in mammary gland, and it was regulated by the corn oil content in the diet. The higher the corn oil content in the diet, the lower the expression of both desaturases. Induction of [Delta]5D and [Delta]6D was associated positively with similar changes in SREBP-1 and PGC-1{szligbeta}. Expression of PPAR[alpha] was barely detected and was not affected by the corn oil content in the diet, whereas PGC-1{szligbeta} expression increased as the corn oil in the diet increased. These results indicate that the lactating mammary gland has the capacity to synthesize PUFAs and can be regulated by the lipid content in the diet.
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