Dietary regulation of mammary lipogenesis in lactating rats

Abstract

The proportion of medium-chain fatty acids (C8:0, C10:0 and C12:0) in rat milk increased significantly between day 4 and day 8 of lactation and for the remainder of lactation these acids comprised 40-50mol% of the total fatty acids. The milk fatty acid composition from day 8 was markedly dependent on the presence of dietary fat and altered to include the major fatty acids of the fats (peanut oil, coconut oil and linseed oil). The distribution of fatty acids made within the gland, however, was independent of dietary lipid and C8:0, C10:0 and C12:0 acids accounted for over 70% of the fatty acids made. The rates of lipogenesis in both the mammary gland and liver determined in vivo after the administration of 3H2O were affected by the presence of dietary lipid. In the mammary gland the rate for rats fed a diet containing peanut oil for 7 days was only one fifth that for rats fed a fat-free diet. Coconut oil also suppressed lipogenesis. Both dietary fats also suppressed lipogenesis in the liver.

Pancreatic Lipase and Its Related Protein 2 Are Regulated by Dietary Polyunsaturated Fat during the Postnatal Development of Rats

“…The amount of PUFA (mainly 18:2) in milk was elevated as maternal dietary polyunsaturated fat increased. This phenomenon is in agreement with previous studies (23)(24)(25). This significant change in the milk fatty acid composition consumed by the pups allowed us to determine whether PL and its related proteins are regulated by dietary fat in the suckling phase and the suckling-nibbling phase, when the pups consume both maternal milk and purified diet.…”

“…The fatty acid composition of maternal milk can be modified by altering the amount of polyunsaturated fat in the lactating dam's diet (23)(24)(25). The aim of this study was to determine whether the amount of polyunsaturated dietary fat can regulate PL, PLRP1, and PLRP2 during development including the suckling only, nibbling-suckling, weanling, and adult phases and to determine whether there is an interaction of this dietary regulation with the developmental regulation of PL and its related proteins when PUFA are introduced as early as the preweanling age.…”

Integration of metabolism in tissues of the lactating rat

“…Lactating rats fed a high fat (20%) diet for 7-20 days show no change in the percentage of fat in the milk but the composition of the milk fat resembles that of the dietary fat [48,49]. In addition, the gain in weight of the pups is not changed on feeding .…”

Isolation and characterization of fatty acid binding proteins from mammary tissue of lactating rats

“…Litter sizes were standardized at ten pups within 48 h of parturition. The rats were fed a commercial pelleted 'breeder' diet (A. E. Reeves, Dunedin, New Zealand) or a semisynthetic 20 % peanut oil diet described previously [34].…”

“…The mammary gland is also an inducible system and previous studies have shown that several lipogenic enzymes increase in activity and amount many-fold at the initiation of lactation [26][27][28][29][30][31][32]. Therefore, we have also measured the concentration of FABP in mammary homogenates prepared from rats at different stages of lactation and after feeding a high-fat diet which is known to reduce mammary fatty acid synthesis [32][33][34].…”