Effects of excessive iodide intake during pregnancy and lactation on lipid metabolism in offspring male rats / 中华地方病学杂志

ABSTRACT

Objective:To study the impact of excessive iodide intake during pregnancy and lactation on lipid metabolism in offspring male rats.Methods:Forty-eight six-week-old Wistar rats (half male and half female) were fed adaptively for one week. The cage was closed according to the ratio of male and female 1∶1. The pregnant rats were divided into two groups according to their weight (220-240 g) by random number table. (1) 10 times high iodine (10 HI) intake during pregnancy and lactation until the postnatal day 21 (PN21) of their offspring pregnant rats were divided into normal iodine group (NI group, drinking deionized water), 10 HI group (drinking potassium iodide solution with iodine content of 2 250 μg/L). Breast milk was used to feed the offspring rats to PN21, and the offspring male rats were taken as the research subjects, with 6 rats in each group. (2) 100 times high iodine (100 HI) intake during pregnancy and lactation to the offspring postnatal day 120 (PN120) pregnant rats were divided into NI group (drinking deionized water) and 100 HI group (drinking potassium iodide solution with iodine content of 24 750 μg/L). After feeding the offspring rats with breast milk until PN21, the offspring were continued to drink potassium iodide solution with the same iodine content as the mother's to PN120. The offspring male rats were taken as the research subjects, with 6 rats in each group. The levels of free triiodothyronine (FT 3), free thyroxine (FT 4), thyrotropin (TSH) in serum, low-density lipoprotein cholesterol (LDL-C), triglyceride (TG) and total cholesterol (TC) in serum and liver tissue homogenates were measured by enzyme-linked immunosorbent assay (ELISA). The mRNA expression of cholesterol 7α-hydroxylase (CYP7A), low-density lipoprotein receptors (LDLR), sterol regulatory element-binding protein (SREBP)-1c, malic enzyme (ME) and thyroid hormone receptor β (TRβ) in the liver tissue were measured by real-time quantitative PCR. Results:(1) Effects of 10 HI intake during pregnancy and lactation on PN21 offspring male rats compared with NI and 10 HI groups, the serum FT 3 [(7.53 ± 0.74), (8.88 ± 0.99) pmol/L], FT 4 [(5.58 ± 0.56), (7.68 ± 0.30) pmol/L], TSH levels [(16.69 ± 1.05), (14.49 ± 0.16) ng/ml] of offspring male rats were statistically significant ( t=- 2.91,-8.76, 3.59, P < 0.05). The levels of LDL-C, TG, TC in serum and liver of offspring male rats of 10 HI group were significantly lower than those of NI group ( t=3.28, 8.71, 3.44, 3.70, 3.49, 2.74, P < 0.05). The differences of mRNA expression levels of LDLR, ME, SREBP-1c in the liver of PN21 offspring male rats of 10 HI and NI groups were statistically significant ( t=- 3.50,-3.92, 5.58, P < 0.05). Among them, the levels of LDLR and ME in 10 HI group were higher than those in NI group, while the level of SREBP-1c in 10 HI group was lower than that in NI group. There no significant difference in CYP7A and TRβ mRNA levels between the two groups ( t=- 2.44, 3.20, P > 0.05). (2) Effects of 100 HI intake during pregnancy and lactation on PN120 offspring male rats there were significant differences in serum FT 3, FT 4 and TSH levels of offspring male rats between 100 HI and NI groups ( t=- 4.39,-3.19, 4.72, P < 0.05). The levels of serum FT 3 and FT 4 in 100 HI group were lower than those in NI group, and the level of TSH in 100 HI group was higher than that in NI group ( P < 0.05). Compared with NI group, the serum and liver LDL-C, TG and TC levels in the offspring male rats of 100 HI group were significantly higher ( t=4.49, 12.85, 16.62, 4.35, 11.04, 16.01, P < 0.05). The differences of CYP7A, LDLR, ME, TRβ and SREBP-1c mRNA levels in liver of PN120 offspring male rats of 100 HI and NI groups were statistically significant ( t=26.40, 54.85,-10.98, 32.52, 10.50, P < 0.05). Among them, the CYP7A, LDLR, ME and TRβ mRNA levels in 100 HI group were lower than those of NI group, while the SREBP-1c mRNA level was higher than that of NI group ( P < 0.05). Conclusions:10 HI intake during pregnancy and lactation to the offspring male rats PN21 showed the serological changes of hyperthyroidism, the levels of blood lipids and liver lipids decreased, the levels of LDLR and ME mRNA increased, and SREBP-1c mRNA decreased in liver. However, 100 HI intake during pregnancy and lactation to the offspring male rats PN120 showed serological changes of hypothyroidism, the levels of blood lipids and liver lipids increased, the levels of CYP7A, LDLR, ME mRNA decreased, and SREBP-1c mRNA increased in liver.