Objectives: To study the correlation of the expression of Lipin1 in visceral adipose tissue and Lipin2 in liver tissue with hepatic fat content in rats with intrauterine growth retardation (IUGR).
Methods: Pregnant rats were given a low-protein (10% protein) diet during pregnancy to establish a model of IUGR in neonatal rats. The pregnant rats in the control group were given a normal-protein (21% protein) diet during pregnancy. The neonatal rats were weighed and liver tissue was collected on day 1 and at weeks 3, 8, and 12 after birth, and visceral adipose tissue was collected at weeks 3, 8, and 12 after birth. The 3.0T 1H-magnetic resonance spectroscopy was used to measure hepatic fat content at weeks 3, 8, and 12 after birth. Real-time PCR was used to measure mRNA expression levels of Lipin2 in liver tissue and Lipin1 in visceral adipose tissue. Western blot was used to measure protein levels of Lipin2 in liver tissue and Lipin1 in visceral adipose tissue. A Pearson correlation analysis was performed to investigate the correlation of mRNA and protein expression of Lipin with hepatic fat content.
Results: The IUGR group had significantly higher mRNA and protein expression levels of Lipin1 in visceral adipose tissue than the control group at weeks 3, 8, and 12 after birth (P<0.05). Compared with the control group, the IUGR group had significantly lower mRNA and protein expression levels of Lipin2 in liver tissue on day 1 after birth and significantly higher mRNA and protein expression levels of Lipin2 at weeks 1, 3, 8, and 12 after birth (P<0.05). At week 3 after birth, there was no significant difference in hepatic fat content between the IUGR and control groups (P>0.05), while at weeks 8 and 12 after birth, the IUGR group had a significantly higher hepatic fat content than the control group (P<0.05). The protein and mRNA expression levels of Lipin1 were positively correlated with hepatic fat content (r=0.628 and 0.521 respectively; P<0.05), and the protein and mRNA expression levels of Lipin2 were also positively correlated with hepatic fat content (r=0.601 and 0.524 respectively; P<0.05).
Conclusions: Upregulation of the mRNA and protein expression levels of Lipin1 in visceral adipose tissue and Lipin2 in liver tissue can increase hepatic fat content in rats with IUGR and may be associated with obesity in adulthood.
目的: 探讨宫内发育迟缓（intrauterine growth retardation，IUGR）大鼠肝脏Lipin2基因和内脏脂肪组织Lipin1基因的表达与肝脏脂肪含量的相关性。方法: 使用母孕期低蛋白（10%蛋白）饮食法喂养孕鼠制造IUGR仔鼠模型，对照组孕鼠在孕期使用正常蛋白饲料喂养（蛋白含量21%）。分别在两组仔鼠生后1 d、1周、3周、8周和12周时称体重并留取仔鼠的肝脏组织，在生后3周、8周和12周留取两组仔鼠的内脏脂肪组织。采用3.0T氢质子磁共振波谱法检测两组大鼠生后3周、8周、12周时肝脏脂肪含量；采用Real-time PCR法检测两组大鼠各时间点肝脏组织Lipin2、内脏脂肪组织Lipin1基因的mRNA表达水平；采用Western blot法检测两组大鼠肝脏组织Lipin2、内脏脂肪组织Lipin1蛋白表达水平。采用Pearson相关分析Lipin mRNA及其蛋白表达与肝脏脂肪含量的相关性。结果: 生后3周、8周、12周时，IUGR组仔鼠内脏脂肪组织Lipin1 mRNA及其蛋白表达水平均高于对照组（P<0.05）。生后1 d时IUGR组肝脏组织Lipin2 mRNA及其蛋白表达水平低于对照组（P<0.05），而生后1周、3周、8周、12周时Lipin2 mRNA及其蛋白表达水平均高于对照组（P<0.05）。生后3周时IUGR仔鼠和对照组肝脏脂肪含量比较差异无统计意义（P>0.05），生后8周、12周时IUGR组仔鼠肝脏脂肪含量显著高于对照组（P<0.05）。Lipin1蛋白和mRNA表达与肝脏脂肪含量呈正相关（分别r=0.628、0.521，P<0.05），Lipin2蛋白和mRNA表达与脂肪含量呈正相关（分别r=0.601、0.524，P<0.05）。结论: IUGR大鼠内脏脂肪组织Lipin1和肝脏组织Lipin2 mRNA及其蛋白表达上调可引起肝脏脂肪含量增加，可能与导致IUGR大鼠成年期肥胖有关。.
Keywords: 1 H-magnetic resonance spectroscopy; Intrauterine growth retardation; Lipin1; Lipin2; Rat.