Methimazole-Induced Hypothyroidism Increases the Content of Glycogen and Changes the Expression of LDH, GLUT4, and Aromatase in the Pregnant Uterus of Rabbits

<b>Objective</b>: To determine the impact of hypothyroidism on uterine glycogen accumulation during pregnancy. <b>Methods</b>: Non-pregnant and pregnant (days 5, 10, and 20) rabbits were grouped into control and methimazole (MMI) groups. In rabbits, serum concentrations of thyroxine (T4), triiodothyronine, glucose, insulin, progesterone, and estradiol were quantified. In uterine inter- and implantation sites, the glycogen content and expression of lactate dehydrogenase (LDH), GLUT4, and aromatase were quantified via Western blot. Fetuses’ characteristics at 20 days of pregnancy were analyzed. Two-way ANOVA was used to compare variables between groups. <b>Results</b>: Pregnancy reduced T4 concentrations but not T3. In virgin groups, MMI treatment significantly reduced the concentrations of T4 and T3 and increased the expression of GLUT4 and aromatase in the uterus compared to the control group. In pregnant groups, T4, T3, glucose, insulin, progesterone, and estradiol levels were similar between control and MMI-treated rabbits. Compared to controls, MMI treatment in pregnant rabbits (a) reduced GLUT4 expression on inter-implantation sites on day 5; (b) increased glycogen content on implantation sites but reduced GLUT4 expression on inter-and implantation sites on day 10; (c) increased glycogen content and LDH and aromatase expression but reduced GLUT4 on inter-implantation sites; and (d) increased glycogen content and the expression of LDH, GLUT4, and aromatase on day 20 on implantation sites. Moreover, the fetus characteristics were similar between groups. <b>Conclusions</b>: MMI-induced hypothyroidism is associated with changes in the uterine content of glycogen and the expression of LDH, GLUT4, and aromatase during pregnancy.