ABSTRACT
Objective To investigate the effect of neonatal overfeeding on the expression of lipid metabolic associated enzymes and molecular mechanisms in the livers of rats. Methods Male Sprague-Dawley rats were randomly assigned to litter sizes of three group ( small litters,SL group) or ten ( normal litters,NL group) on postnatal day 3. Body weight,milk intake,liver and fat pad (epididymal and retroperitonea) weight,and hepatic histological anal-ysis were recorded in week 2 and week 3,respectively. The levels of lipids were detected by the automatic biochemical analyzer. The mRNA expressions of acetyl-CoA carboxylase ( ACC) ,lipoprotein lipase ( LPL) ,liver-type fatty acid-binding protein (L-FABP), carnitine palmitoyltransferase 1(CPT1),microsomal triglyceride transfer protein (MTP), sterol regulatory element-binding protein-1c (SREBP-1c) and peroxisome proliferator activated receptorα(PPARα) in liver were determined by real time PCR;the protein expressions of SREBP-1c and PPARα were determined by Western lot. Results As early as week 2,the body weight of rats in SL group began to elevate (t=-5. 997,P<0. 001) and food intake (t=-3. 462,P=0. 002) compared with the rats in NL group,and persistent to weaning (body weight:t=-17. 019,P<0. 001;food intake:t=-2. 276,P=0. 031). By the time of 3 weeks old,SL rats increased visceral fat pad [ret-roperitonea (t=-7. 643,P<0. 001),epididymal (t=5. 997,P=0. 001)],liver weight (t=-7. 812,P<0. 001),hepatosomatic index (t=-3.829,P=0. 003) and serum triglyceride (TG) level (t=-2. 703,P=0. 022) compared with those of NL rats,as well as the level of hepatic ACC mRNA (t=-3. 751,P=0. 007),LPL (t=-2. 721,P=0. 017) and L-FABP mRNA (t=-2. 521,P=0. 026) . While CPT1 mRNA (t=-1. 531,P=0. 155) and MTP mRNA (t=-1. 741,P=0. 098) levels remained unchanged in both groups. Hepatic SREBP-1c mRNA expression increased in SL rats after 2 to 3 weeks (t=-2. 836,P=0. 016),paralleled with ACC and LPL mRNA expression;while the mRNA and protein expression of PPARα re-mained unchanged (t=-0. 854,P=0. 411). Conclusions Postnatal overfeeding can promote higher liver pad and dyslip-idemia at the time of weaning. The process may be regulated by up-regulated expression of ACC, LPL and L-FABP. SREBP-1c may be participated in the regulation of ACC,a rate-limiting enzyme involved in lipogenesis.