[A study on membrane fluidity of thyroid gland in rats with iodine deficiency or iodine excess].
OBJECTIVE
To explore the effect of iodine deficiency and excess on thyroid membrane fluidity and its pathogenesis.


METHODS
Wistar rats were fed different levels of iodine in the diet (normal iodine as control, low iodine and excess iodine). Serum T4 and T3 levels, thyroid superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and malondialdehyde (MDA) content were determined, and two parameters of polarization (Pr) and micro-viscosity (eta) using DPH as a florescence probe were tested.


RESULTS
Serum T4 and T3 levels in the low iodine (LI) group were markedly decreased, and the thyroid SOD and GPx activities and MDA content were significantly increased compared with the other two groups. However no changes were found in the high iodine (HI) group. There were no differences in Pr and eta values among three groups at 12th week of experiment, but at 24th week, both Pr and eta values in LI group were increased significantly compared to the other two groups. But the effect of iodine excess as expected was not found in this study.


CONCLUSIONS
Long-term iodine deficiency caused a marked increase of membrane micro-viscosity and decrease of membrane fluidity in rat thyroid gland. Oxidative damage of thyroid by free radicals and retardation of lipid metabolism are considered as two important pathogenesis factors.
Yan
Y
Y
Institute of Endocrinology, Tianjin Medical University, Tianjin 300070, China.
Fang
H
H
Xiang
J
J
D000818:Animals; D005260:Female; D007455:Iodine / Q000172:deficiency* / Q000494:pharmacology; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013961:Thyroid Gland / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood
D007455:Iodine; D013974:Thyroxine