Effect of variation of trans-fatty acid in lactating rats' diet on lipoprotein lipase activity in mammary gland, liver, and adipose tissue.
OBJECTIVE
Lactation is associated with an increase in lipoprotein lipase (LPL) activity in the mammary gland (MG) and a decrease in adipose tissue because lactation redirects circulating substrates to the MG for milk synthesis. We investigated the effects of different dietary contents of trans-fatty acid (TFA) on LPL activity in maternal tissues and fatty acid composition in milk.


METHODS
Lactating rats were fed semisynthetic isocaloric diets containing 7% soy oil (control), 7% partially hydrogenated vegetable oil (7%-PHVO), 5% PHVO plus 2% soy oil (5%-PHVO), or 3.5% PHVO plus 3.5% soy oil (3.5%-PHVO). On lactation day 14, animals were decapitated and MG, liver, and parametrial adipose tissue were extracted to determine total lipid contents, percentages of TFA, and LPL activity. Milk lipid composition was examined by gas chromatographic analysis of the gastric content of 14-d-old suckling pups.


RESULTS
Maternal consumption of TFA increased dietary TFA incorporation in MG and liver and decreased it in parametrial adipose tissue. Diets with higher trans concentrations (7%-PHVO) significantly increased lipid content in the MG, and all groups fed trans-based diets showed significant increases in LPL activity in the MG. Although LPL increased in the MG, milk of rats fed TFA-based diets had significant decreases in the percentage of essential fatty acids.


CONCLUSIONS
TFA intake during lactation alters maternal lipid metabolism and the percentage of essential fatty acids in milk; therefore, it is important to alert the population to avoid excessive intake of TFAs during lactation.
Instituto de Nutrição Josué de Castro, Universidade Federal do Rio de Janeiro, Brazil.
Renata Pereira
RP
Assumpção
Flávia Duarte
FD
dos Santos
Priscila
P
de Mattos Machado Andrade
Giselle Freire
GF
Barreto
Maria
M
das Graças Tavares do Carmo
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D002849:Chromatography, Gas / Q000379:methods; D004032:Diet / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D007774:Lactation / Q000378:metabolism*; D008071:Lipoprotein Lipase / Q000187:drug effects / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D039382:Maternal Nutritional Physiological Phenomena / Q000502:physiology; D010938:Plant Oils / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D013024:Soybean Oil / Q000008:administration & dosage; D044242:Trans Fatty Acids / Q000008:administration & dosage / Q000494:pharmacology*
D010938:Plant Oils; D044242:Trans Fatty Acids; D013024:Soybean Oil; D008071:Lipoprotein Lipase