Pre- and postnatal dietary conjugated linoleic acid alters adipose development, body weight gain and body composition in Sprague-Dawley rats

Sprague-Dawley rats were fed either a control diet (7 g/100 g soybean oil) or a conjugated linoleic acid (CLA) diet (6.5 g/100 g soybean oil and 0.5 g /100 g CLA) beginning on d 7 of gestation to determine whether pre- and pos tnatal CLA affects short- and long-term growth and adiposity. At weaning (d 21), progeny were assigned control or CLA diet and fed until 11 wk of age. At birth, litter size and weight were not different between treatments. Th ere were age- and sex-dependent changes in inguinal adipose fatty acid comp osition at birth and weaning, whereas there were no differences in lipid ac cretion or adipocyte proliferation. At weaning, CLA did not alter inguinal adipocyte proliferation but increased (P < 0.01) CCAAT/enhancer binding pro tein alpha expression in inguinal adipose tissue from females, whereas ther e was no difference in expression in males. Significant differences in size distribution of inguinal adipocytes at weaning and retroperitoneal adipocy tes at 11 wk of age were observed. In general, CLA increased the proportion of smaller cells and decreased the proportion of larger cells. The main lo ng-term effect of the dams' diet was the significantly heavier gastrocnemiu s and soleus muscles, and significantly longer tail lengths, an indication of skeletal growth, of male pups whose dams were fed CLA. Postweaning diet reduced fat pad weights in female but not male pups fed CLA. This response was due to differences in cell size rather than number. Response to CLA tre atment may depend on the sex and age of the animal as well as duration of f eeding.