Intranasal deferoxamine reverses iron-induced memory deficits and inhibits amyloidogenic APP processing in a transgenic mouse model of Alzheimer's disease.

Increasing evidence indicates that a disturbance of normal iron homeostasis and an amyloid-ß (Aß)-iron interaction may contribute to the pathology of Alzheimer's disease (AD), whereas iron chelation could be an effective therapeutic intervention. In the present study, transgenic mice expressing amyloid precursor protein (APP) and presenilin 1 and watered with high-dose iron served as a model of AD. We evaluated the effects of intranasal administration of the high-affinity iron chelator deferoxamine (DFO) on Aß neuropathology and spatial learning and memory deficits created in this AD model. The effects of Fe, DFO, and combined treatments were also evaluated in vitro using SHSY-5Y cells overexpressing the human APP Swedish mutation. In vivo, no significant differences in the brain concentrations of iron, copper, or zinc were found among the treatment groups. We found that high-dose iron (deionized water containing 10 mg/mL FeCl(3)) administered to transgenic mice increased protein expression and phosphorylation of APP695, enhanced amyloidogenic APP cleavage and Aß deposition, and impaired spatial learning and memory. Chelation of iron via intranasal administration of DFO (200 mg/kg once every other day for 90 days) inhibited iron-induced amyloidogenic APP processing and reversed behavioral alterations. DFO treatment reduced the expression and phosphorylation of APP protein by shifting the processing of APP to the nonamyloidogenic pathway, and the reduction was accompanied by attenuating the Aß burden, and then significantly promoted memory retention in APP/PS1 mice. The effects of DFO on iron-induced amyloidogenic APP cleavage were further confirmed in vitro. Collectively, the present data suggest that intranasal DFO treatment may be useful in AD, and amelioration of iron homeostasis is a potential strategy for prevention and treatment of this disease.

[Effects of selenium supplementation on antibodies of autoimmune thyroiditis].

OBJECTIVE: To evaluate the effects of selenium (Se) supplementation on concentrations of thyroid peroxidase antibodies (TPOAb) and TPOAb IgG subclasses in autoimmune thyroiditis (AIT) patients with different thyroid functional status. METHODS: A blind and placebo-controlled prospective study was performed for a total of 134 cases with AIT and thyroid peroxidase antibodies above 300 U/ml. Their mean age was 41 years (range: 15-70). All of them were recruited from Department of Endocrinology, First Affiliated Hospital of China Medical University from June 2008 to June 2009 and divided into 2 groups according to thyroid function: euthyroidism or subclinical hypothyroidism (n = 89) and hypothyroidism (n = 45). Then they were randomized into 2 groups: selenium-treated and placebo-treated. And 49 cases in subclinical autoimmune thyroiditis group and 28 cases in hypothyroidism group received 200 µg oral selenium yeast daily for 6 months while others placebo. Serum concentrations of TPOAb, TPOAb IgG subclasses, thyroid-stimulating hormone (TSH), free thyroxine (FT(4)) and Se were measured at baseline and after 3 and 6 months of follow-up. RESULTS: The TPOAb levels showed an overall decrease of 4.3% at 3 months and of 12.6% at 6 months (both P < 0.05) post-supplementation in subclinical autoimmune thyroiditis patients. In overt hypothyroidism patients, the overall decrease of TPOAb concentrations was 21.9% at 3 months and 20.4% at 6 months (both P < 0.05) compared with those at pre-treatment. The predominant TPOAb IgG subclasses in sera from the AIT patients were IgG1, IgG3 and IgG4 and the positive percentages 72%, 41% and 72% respectively. The positive rate and concentrations of IgG3 in the patients with hypothyroidism were significantly higher than those of subclinical autoimmune thyroiditis (P < 0.05). Significant decreases in IgG1 and IgG3 levels were noted in subclinical autoimmune thyroiditis group at 6 months post-supplementation (P < 0.05). IgG1 levels in overt hypothyroidism decreased significantly compared with those at pre-supplementation (P < 0.05). In all patients with supplementation (n = 77), the TPOAb levels decreased in 52 at 6 months while increase or no change occurred in 25. The positive percentage and concentrations of IgG1 in patients whose TPOAb levels decreased at 6 months post-supplementation were markedly higher than those whose TPOAb levels increased (P < 0.05). CONCLUSION: Se is effective in reducing TPOAb concentrations and the predominant decreasing TPOAb IgG subclasses are IgG1 and IgG3. And a high level of IgG1 subclass may explain the difficult decline of TPOAb.

[Effect of chronic mild and moderate iodine excess on thyroid anti-oxidative ability of iodine deficiency and non-iodine deficiency Wistar rats].

OBJECTIVE: To investigate the effects of chronic mild and moderate iodine excess on thyroid oxidative injury and anti-oxidative ability of iodine deficiency and non-iodine deficiency Wistar rats. METHODS: Four-week-old Wistar rats were fed with iodine deficient diet for three months to make iodine deficient goiter models, then divided randomly into three groups: iodine deficient control group (Group IDC) fed with double distilled water, iodine-supplement group I (Group IS I) fed with potassium iodate solutions with the iodine concentrations of 100 microg/L, and iodine-supplement group II (Group IS II), fed with potassium iodate solution with the iodine concentrations of 330 microg/L. Another four-week-old Wistar rats were fed with normal diet for three months, and then divided randomly into three groups: normal control group (NC) fed with double distilled water, iodine-excess group I (IEI) fed with potassium iodate solution with the iodine concentration of 300 microg/L, and iodine-excess group II (Group IEII), fed with potassium iodate solution with the iodine concentration of 660 microg/L. 1, 2, 4, 8, and 24 weeks after treatment samples of urine were collected to detect the median urine iodine (MUI), samples of plasma were collected from the hearts of 8-14 rats from each group and then rats were killed. Their thyroid glands were taken out to measure the wet weight and made into homogenate. Biochemical method was used to measure the activities of glutathione-peroxidase (GSH-P(X)) and superoxide dismutase (SOD) as well as the contents of malonyldialdehyde (MDA) and H2O2 in the homogenates of thyroid glands. RESULTS: The GSH-P(X) activity 2 weeks after treatment of Group IS II was significantly lower than that of Group IDC (P < 0.05), and the GSH-P(X) activity 4 weeks after treatment of Group IS I was significantly lower than that of Group IDC (P < 0.001). The activities of GSH-P(X) 4, 8, and 24 weeks after treatment of Groups IS I and IS II were all lower than those of Group C at the same time points significantly (P < 0.001, < 0.01, and < 0.05 respectively). The activities of SOD were decreased gradually in Groups IS I and IS II and were significantly lower than those of Group IDC since 8 weeks after treatment (P < 0.001 or < 0.05). The SOD activities in thyroid glands of Groups IEI and IEII since 8 weeks after treatment decreased significantly in comparison with Group NC (all P < 0.01 or < 0.001). The contents of H2O2 in thyroid glands of Groups IS I and IS II were significantly lower than those of Group IDC at different time points (P < 0.001, < 0.01, or < 0.05), and were significantly lower than those of Group NC 8 and 24 weeks after treatment (P < 0.001 or < 0.01). The contents of MDA in thyroid glands since 2 weeks after treatment of Group IEI were all significantly lower than those of Group IDC at the same time points (all P < 0.05), and the content of MDA in thyroid glands since 1 week after treatment of Groups IS II were all significantly lower than those of Group IDC at the same time points (all P < 0.05). CONCLUSION: Supplementation of 100 microg/L and 330 microg/L iodine on iodine deficiency Wistar rats may alleviate the oxidative injury but weaken the anti-oxidative protection of thyroid. The anti-oxidative protection of thyroid glands of non-iodine deficiency Wistar rats may also be weakened by supplementation of 300 microg/L and 660 microg/L iodine.

Multivariate analysis of relationships between iodine biological exposure and subclinical thyroid dysfunctions.

OBJECTIVE: To assess the relationships between iodine biological exposure and subclinical thyroid dysfunctions. METHODS: The cross-sectional survey was performed to obtain the epidemiologic data of population in three communities with different iodine biological exposure: mild iodine deficiency [median urinary iodine concentration (MUI) of 50-99 microg/L], more than adequate iodine intake (MUI of 200-299 microg/L), and excessive iodine intake (MUI over 300 microg/L). Univariate and multivariate analysis (logistic regression analysis) were used to analyze the risk factors of subclinical hypothyroidism and subclinical hyperthyroidism. RESULTS: Logistic regression analysis with sex and age controlled suggested that more than adequate iodine intake (OR = 3.172, P = 0.0004) and excessive iodine intake (OR = 6.391, P = 0.0001) increased the risk of subclinical hypothyroidism, while excessive iodine intake decreased the risk of subclinical hyperthyroidism (OR = 0.218, P = 0.0001). Logistic regression analysis including interaction of iodine intake and antibodies [thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb)] suggested that excessive iodine intake was an independent risk factor of subclinical hypothyroidism (OR = 6.360, P = 0.0001), but independent protect factor of subclinical hyperthyroidism (OR = 0.193, P = 0.0001). More than adequate iodine intake and it's interaction with TgAb increased the risk of subclinical hypothyroidism independently, in addition, it decreased the risk of subclinical hyperthyroidism at the present of TPOAb. CONCLUSION: Both excessive iodine intake and more than adequate iodine intake could increase risk of subclinical hypothyroidism, supplement of iodine should be controlled to ensure MUI within the safe range.