Effect of progestin on thyroid function in female Wistar rats.

Introduction: To characterize the influence of female-specific hormones on women's thyroid function, the study investigated the influence of extra progestin from oral contraceptives on inducing thyroid dysfunction. Methods: Sixty female Wistar rats were divided into six groups based on levonorgestrel or desogestrel administration as the main active agents: control, low (0.0039 mg*20-fold), medium (0.0039 mg*100-fold), high (0.0318 mg*100-fold) levonorgestrel (pure product); and low (0.0083 mg*20-fold) and high (0.0083 mg*100-fold) desogestrel (pure product). Progestin was administered by gavage every 4 days for 1 month. Statistical analysis was performed using one-way analysis of variance and the Kruskal-Wallis test. Results: Following levonorgestrel gavage, serum free T4 and thyroidstimulating hormone levels were significantly lower in the experimental group than that in the control group (p=0.013 and 0.043). After desogestrel gavage, the serum free T4 and free T3 levels were lower in the experimental group than that in the control group (p=0.019 and 0.030). Thyroid hormone antibody concentrations were lower in rats administered levonorgestrel and desogestrel than that in control rats. Moreover, exposure to progestin upregulated the expression of the thyroid-stimulating hormone receptor and sodium iodide symporter in thyroid. Discussion: Progestin stimulation enhanced the proliferation of follicular epithelial cells in rat thyroid tissues. Progestin exposure could cause thyroid dysfunction by upregulating the transcription of thyroid-stimulating hormone receptor and sodium iodide symporter in thyroid, thus inducing pathomorphological changes in rats' thyroid.

Protection of Vitamin C on Oxidative Damage Caused by Long-Term Excess Iodine Exposure in Wistar Rats.

Vitamin C was reported to be able to protect against oxidative damage due to its reducibility. 120 Wistar rats were randomly divided into 4 × 2 groups, including normal iodine (NI), high iodine (HI), low vitamin C (HI + LC), and high vitamin C (HI + HC); potassium iodide (KI) and potassium iodate (KIO3) were commonly used as additives for iodized salt, so every group was also divided into KI and KIO3 groups. After 6 months' feed, the activities of antioxidant enzymes and Lipid Peroxide (MDA) content in serum, liver, kidney, brain, thyroid and lens were determined. In serum, for males, long-term excess iodine intake caused oxidative damage; in the liver, male rats in the HI + LC group had the highest MDA content, which showed that low-dose vitamin C might promote oxidative damage; in kidneys, the MDA content in the HI and HI + LC groups of females was higher; in the brain, high-dose vitamin C could increase the activity of superoxide dismutase (SOD), which was decreased by high iodine intake, and it also decreased MDA content; in the thyroid, for KIO3, the activity of SOD in the HI group was lower than NI and HI + LC; in the lens, the MDA content in females was lower than males. Long-term excess iodine exposure caused oxidative damage and showed sex difference, and vitamin C had a protective effect on it, especially for high-dose vitamin C.

The relationship between different iodine sources and nutrition in pregnant women and adults.

Background: Different iodine supplement measures emerge along with the economy development in China. The article objectives are to compare and explore the relationship between iodine sources and nutrition of pregnant women and adults. Methods: A total of 2,145 pregnant women and 1,660 adults were investigated by multi-stage random method. Questionnaire was used to collect basic information and the consumption of food, water, and iodine preparations. Household salt and individual urine and blood samples were collected, and thyroid function and morphology of pregnant women were measured. Results: The median urinary iodine concentration (MUIC) of pregnant women (164.49 µg/L) was lower than adults (187.30 µg/L, p < 0.05). Iodine supplement with IS (iodized salt) was the main measure for pregnant women and adults, and the difference was mainly on the consumption of iodine preparations between pregnant women (5.19%) and adults (0.85%). Moreover, adults' dietary iodine intake from food (100.6 µg/day), IS (140.8 µg/day), and drinking water (6.0 µg/day) was higher than those of pregnant women (86.5, 107.2, and 3.5 µg/day, respectively). Compared with iodine supplement with IS, ISFP (IS + iodine-rich food + iodine preparations) could reduce the risk of iodine deficiency for pregnant women. The MUICs for pregnant women and adults of iodine supplements with IF (iodine-rich food) and ISF (IS + iodine-rich food) were lower. For pregnant women, thyroid nodule (11.90%) and peroxidase antibody (TPOAb) positive (9.32%) were high prevalent thyroid diseases, and habitation (urban/rural), gestation, annual income, and drinking water type would affect them. Conclusion: Pregnant women and adults had adequate iodine nutrition in four provinces. Their iodine supplement measures were different, the consumption of iodine preparations in pregnant women was higher, and their dietary iodine intake was lower than adults. ISFP was an effect measure for pregnant women to supplement iodine.