Analysis of the correlation between lipotoxicity and pituitary-thyroid axis hormone levels in men and male rats

// Jianmei Yang 1,2,3 , Xiaoming Zhou 1,2,3 , Xu Zhang 1,2,3 , Jianting Hu 4 , Ling Gao 2,3,5 , Yongfeng Song 1,2,3 , Chunxiao Yu 1,2,3 , Shanshan Shao 1,2,3 , Zhongshang Yuan 6 , Yan Sun 7 , Huili Yan 2,3 , Guimei Li 7 and Jiajun Zhao 1,2,3 1 Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China 2 Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong, China 3 Shandong Clinical Medical Center of Endocrinology and Metabolism, Jinan, Shandong, China 4 Shandong Academy of Pharmaceutical Sciences, Jinan, Shandong, China 5 Scientific Center, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China 6 Department of Epidemiology and Biostatistics, School of Public Health, Shandong University, Jinan, Shandong, China 7 Department of Pediatric Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China Correspondence to: Jiajun Zhao, email: // Guimei Li, email: // Keywords : lipotoxicity; high-fat lard diet; hypertriglyceridemia; anterior pituitary hormones; pituitary-thyroid axis; Pathology Section Received : February 29, 2016 Accepted : June 03, 2016 Published : June 14, 2016 Abstract Lipotoxicity seriously harms human health, but it is unclear whether lipotoxicity is detrimental to the pituitary. We investigated the correlation between serum triglyceride and pituitary axis hormone levels in epidemiological and animal studies. In the epidemiological study, serum thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were greater in male patients with isolated hypertriglyceridemia than in controls, whereas adrenocorticotropin (ACTH) levels were lower in the patients with hypertriglyceridemia. Pituitary hormone levels correlated with triglyceride levels, even after adjustment for potential confounders. In the animal study, male rats were fed a high-fat or control diet for 28 weeks. As the duration of high-fat feeding increased, the serum and pituitary triglyceride concentrations increased. At early times, the high-fat diet elevated serum TSH and triiodothyronine. At later times, much higher serum TSH levels coupled with reduced thyroxine were observed in the high-fat group. Serum levels of pituitary-gonadal and pituitary-adrenal axis hormones were not affected by the diet. The mRNA and protein expression of Tshβ were greater in the high-fat group than in the control group, whereas expression of Fshβ , Lhβ and Acth had no difference between the groups. Overall, serum triglyceride levels were associated with pituitary-thyroid axis hormone levels.