Effect of dietary levels of corn oil on maternal arachidonic acid synthesis and fatty acid composition in lactating rats.
OBJECTIVE
We examined the effect of different amounts of dietary corn oil rich in linoleic acid (LA) on the endogenous synthesis of arachidonic acid (AA), uptake of its precursor LA, and fatty acid composition of tissues involved in the supply of long-chain polyunsaturated fatty acids for milk synthesis.


METHODS
Female Sprague Dawley rats received one of the following diets during pregnancy and lactation: a low-lipid diet (LLD; 2%), an adequate-lipid diet (ALD; 5%), or a high-lipid diet (HLD; 10%). Lipids were provided by corn oil. On day 12 of lactation we measured the endogenous synthesis of AA and quantified the conversion of (13)C-LA to (13)C-AA and the metabolic fate of (13)C-LA from all dietary groups.


RESULTS
The LLD rats demonstrated larger amounts of endogenous synthesis of (13)C-AA and more dietary (13)C-LA transferred to the mammary gland (MG) than HLD rats during lactation. The proportion of medium-chain fatty acids was higher in the MG, milk clot, and liver of LLD than of HLD rats. Daily volume and 24-h yield of lipids and energy were lower in LLD rats than in HLD rats. Measurements of milk composition demonstrated that fat concentration significantly increased as lipid concentration increased in the diet.


CONCLUSIONS
These results suggest that maternal adaptations used to compensate for diets deficient in long-chain polyunsaturated fatty acids include increased endogenous synthesis of AA and elevated uptake of LA in the MG and increased synthesis of medium-chain polyunsaturated fatty acids. It appears that the MG and liver participate together for AA synthesis for milk when this fatty acid is not provided in the diet.
Laboratorio de Biología Molecular, Unidad de Investigación Médica en Nutrición, Hospital de Pediatría, Centro Medico Nacional Siglo XXI, Mexican Institute of Social Security, Mexico City, Mexico. giraviol@yahoo.es
Maricela
M
Rodríguez-Cruz
Raúl
R
Sánchez
Mariela
M
Bernabe-Garcia
Jorge
J
Maldonado
Martha
M
Del Prado
Mardia
M
López-Alarcón
D000222:Adaptation, Physiological; D000818:Animals; D016718:Arachidonic Acid / Q000008:administration & dosage / Q000096:biosynthesis*; D002247:Carbon Isotopes; D003314:Corn Oil / Q000494:pharmacology*; D018752:Diet, Fat-Restricted; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D007774:Lactation / Q000187:drug effects* / Q000378:metabolism*; D019787:Linoleic Acid / Q000008:administration & dosage / Q000378:metabolism; D008892:Milk / Q000737:chemistry*; D011247:Pregnancy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D002247:Carbon Isotopes; D005227:Fatty Acids; D016718:Arachidonic Acid; D003314:Corn Oil; D019787:Linoleic Acid