Journal of Food, Agriculture and Environment

Effects of dietary protein levels and genetic background on enzyme and transcription factor mRNA expression in subcutaneous adipose tissues in swine

Author(s):

Wanting Gu ^{1, 2#}, Peng Ying ^3#, Min Gong ^{1, 4#}, Zheng Ruan ^1*, Yongfei Wang ⁵, Ronghua Yin ⁵, Xugang Shu ⁶, Mingzhe Fan ⁷, Zhi-qiang Liu ^2*

Recieved Date: 2010-07-22, Accepted Date: 2010-11-06

Abstract:

The aim of this study was mainly to investigate the effects of dietary crude protein (CP) levels on growth and carcass performance, serum parameter and the mRNA expression of enzymes and transcription factors in subcutaneous adipose tissues in obese and lean swine. Twenty seven obese-type Ningxiang breed fattening pigs and thirty six lean-type hybrid (Duroc×Landrace×Yorkshire) fattening pigs were randomly allocated to three by two groups, fed low, middle and high CP diets, respectively, for a 46-day period. The CP levels in the diets were 10.41% (low), 12.91% (middle) and 15.43% (high) for Ningxiang; 12.91% (low), 15.43% (middle) and 19.66% (high) for the hybrid according to their own standard maintenance requirement, respectively. All diets were identical in calories. On day 46, blood samples were collected for analysis of serum lipoprotein, total cholesterol, triglycerides and leptin levels. Following the blood collection, 4 pigs from each group were killed and subcutaneous adipose tissues were collected for the analysis of mRNA expression of lipogenic and lipolytic enzymes and transcription factors. Results indicated that dietary CP levels had no significant effect on growth and carcass performance, serum parameter and mRNA expression of lipogenic and lipolytic key enzymes and transcription factors except leptin and sterol regulatory element-binding protein-1c (SREBP-1c). Increases in dietary CP levels resulted in the increase of leptin and decrease of SREBP-1c mRNA expression in subcutaneous adipose tissues. However, there were marked differences in growth and carcass performance, serum parameter and mRNA expression of lipogenic and lipolytic key enzymes and transcription factors between the two breed. The percentage of fat and feed gain ratio, serum triglycerides, total cholesterol, low density lipoprotein and leptin content and the levels of hormone-sensitive lipase (HSL), lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor-γ (PPARγ) mRNA in subcutaneous adipose tissues were significantly higher in Ningxiang pigs. The average fat thickness was positively correlated with the abundance of HSL, LPL, leptin, PPARγ and liver X receptor-α (LXRα) mRNA in subcutaneous adipose tissues. Furthermore, leptin was positively correlated with LPL and LXRα, and was negatively correlated with SREBP-1c of mRNA expression in subcutaneous adipose tissues. These findings suggest that obese and lean genotype fattening pigs have distinct manners in lipid metabolism, the Ningxiang deposited higher energy than hybrid. Some lipid key enzymes (HSL, LPL) and transcription factors (PPARγ, SREBP-1c, LXRa) may participate in the regulation of lipid metabolism via leptin signaling. Dietary protein may indirectly act on these enzymes and transcription factors to influence the subcutaneous lipid metabolism.

Keywords:

Dietary protein, fattening pigs, Ningxiang breed, Duroc×Landrace×Yorkshire hybrid, subcutaneous, mRNA expression

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Journal: Journal of Food, Agriculture and Environment
Year: 2010
Volume: 8
Issue: 3&4
Category: Food and Health
Pages: 56-65

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