title: Transcriptomic analysis of hepatic responses to testosterone deficiency in miniature pigs fed a high-cholesterol diet.
abstract: BACKGROUND
  Recent studies have indicated that low serum testosterone levels are associated with increased risk of developing hepatic steatosis; however, the mechanisms mediating this phenomenon have not been fully elucidated. To gain insight into the role of testosterone in modulating hepatic steatosis, we investigated the effects of testosterone on the development of hepatic steatosis in pigs fed a high-fat and high-cholesterol (HFC) diet and profiled hepatic gene expression by RNA-Seq in HFC-fed intact male pigs (IM), castrated male pigs (CM), and castrated male pigs with testosterone replacement (CMT).
  
  
  RESULTS
  Serum testosterone levels were significantly decreased in CM pigs, and testosterone replacement attenuated castration-induced testosterone deficiency. CM pigs showed increased liver injury accompanied by increased hepatocellular steatosis, inflammation, and elevated serum alanine aminotransferase levels compared with IM pigs. Moreover, serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were markedly increased in CM pigs. Testosterone replacement decreased serum and hepatic lipid levels and improved liver injury in CM pigs. Compared to IM and CMT pigs, CM pigs had lower serum levels of superoxide dismutase but higher levels of malondialdehyde. Gene expression analysis revealed that upregulated genes in the livers of CM pigs were mainly enriched for genes mediating immune and inflammatory responses, oxidative stress, and apoptosis. Surprisingly, the downregulated genes mainly included those that regulate metabolism-related processes, including fatty acid oxidation, steroid biosynthesis, cholesterol and bile acid metabolism, and glucose metabolism. KEGG analysis showed that metabolic pathways, fatty acid degradation, pyruvate metabolism, the tricarboxylic acid cycle, and the nuclear factor-kappaB signaling pathway were the major pathways altered in CM pigs.
  
  
  CONCLUSIONS
  This study demonstrated that testosterone deficiency aggravated hypercholesterolemia and hepatic steatosis in pigs fed an HFC diet and that these effects could be reversed by testosterone replacement therapy. Impaired metabolic processes, enhanced immune and inflammatory responses, oxidative stress, and apoptosis may contribute to the increased hepatic steatosis induced by testosterone deficiency and an HFC diet. These results deepened our understanding of the molecular mechanisms of testosterone deficiency-induced hepatic steatosis and provided a foundation for future investigations.
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. zwc_zjtcm@hotmail.com.
authors.forename: Zhaowei
authors.initials: Z
authors.lastname: Cai
authors.affiliation: Department of Cancer Genetics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY, 14263, USA. xiaoling.jiang@roswellpark.org.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. yongmp@163.com.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. chl810@foxmail.com.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: College of Animal Science, Nanjing Agricultural University, Nanjing, 310058, China. lfzhang777@163.com.
authors.forename: Lifan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. zjzygyz@126.com.
authors.forename: Keyan
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. cyq810@hotmail.com.
authors.forename: Yueqin
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. lyun1983@163.com.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ling
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. ucika@sina.com.
authors.forename: Fangming
authors.initials: F
authors.lastname: Chen
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. labanim1983@sina.com.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Xu
authors.affiliation: Laboratory Animal Research Center, Zhejiang Chinese Medical University, Hangzhou, 310053, China. cml-zjtcm@hotmail.com.
authors.forename: Minli
authors.initials: M
authors.lastname: Chen
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000008:administration & dosage / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism; D005234:Fatty Liver / Q000378:metabolism / Q000473:pathology; D050155:Lipogenesis; D008077:Lipoproteins, LDL / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018384:Oxidative Stress; D013552:Swine; D013556:Swine, Miniature / Q000235:genetics* / Q000378:metabolism; D013739:Testosterone / Q000172:deficiency* / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D008077:Lipoproteins, LDL; D014280:Triglycerides; D013739:Testosterone; D002784:Cholesterol