Gestational hypothyroidism elicits more pronounced lipid dysregulation in mice than pre-pregnant hypothyroidism.

Thyroid hormone is crucial for regulating lipid and glucose metabolism, which plays essential role in maintaining the health of pregnant women and their offspring. However, the current literature is just focusing on the development of offspring born to the untreated mothers with hypothyroidism, rather than mothers themselves. Additionally, the interaction between hypothyroidism and pregnancy, and its impact on the women's health are still elusive. Therefore, this study was designed to compare the metabolic differences in dams with hypothyroidism starting before pregnancy and after pregnancy. Pre-pregnant hypothyroidism was generated in 5-week-old female C57/BL/6J mice using iodine-deficient diet containing 0.15% propylthiouracil for 4 weeks, and the hypothyroidism was maintained until delivery. Gestational hypothyroidism was induced in dams after mating, using the same diet intervention until delivery. Compared with normal control, gestational hypothyroidism exhibited more prominent increase than pre-pregnant hypothyroidism in plasma total cholesterol and low-density lipoprotein cholesterol, and caused hepatic triglycerides accumulation. Similarly, more significant elevations of protein expressions of SREBP1c and p-ACL, while more dramatic inhibition of CPT1A and LDL-R levels were also observed in murine livers with gestational hypothyroidism than those with pre-pregnant hypothyroidism. Moreover, the murine hepatic levels of total cholesterol and gluconeogenesis were dramatically and equally enhanced in two hypothyroid groups, while plasma triglycerides and protein expressions of p-AKT, p-FoxO1 and APOC3 were reduced substantially in two hypothyroid groups. Taken together, our current study illuminated that gestational hypothyroidism may elicit more pronounced lipid dysregulation in dams than dose the pre-pregnant hypothyroidism.