Evaluation of the genotoxic effects of thyroxine using in vivo cytogenetic test on Swiss albino mice

The aim was to study the genotoxic effect of high concentration of thyroxine (T4) in vivo in peripheral blood lymphocytes (PBL) of the patients suffering from thyroid disorders. The effect was compared by performing in vitro experiments with addition of increasing concentration of T4 (0.125-1 µM) in whole blood samples from healthy donors. Cytokinesis-blocked micronuclei (CBMN) assay method was used to assess the DNA damage in the PBL. The study included 104 patients which were grouped as control (n = 49), hyperthyroid (n = 31) and hypothyroid (n = 24). A significant increase in micronuclei (MN) frequency was observed in hyperthyroid patients when compared with the hypothyroid and euthyroid group thereby suggesting increased genotoxicity in hyperthyroidism (p < 0.001). A significant increase in MN frequency was observed at T4 concentration of 0.5 µM and above when compared to lower T4 concentrations (0.125 and 0.25 µM) and basal in in vitro experiments (p = 0.000). The results indicate that the T4 in normal concentration does not exhibit the genotoxic effect, as observed in both the in vivo and in vitro experiments. The toxicity of T4 increases at and above 0.5 μM concentration in vitro. Therefore acute T4 overdose should be handled promptly and effectively so as to avoid the possible genotoxic effect of high concentration of T4 in vivo.

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Effect of l-Thyroxine on Micronuclei Frequency in Peripheral Blood Lymphocytes in Clinical and Experimental Conditions

Raut

Bhartiya

Kand

et al. 2015

Ind J Clin Biochem

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Dry Olive Leaf Extract Counteracts L-Thyroxine-Induced Genotoxicity in Human Peripheral Blood LeukocytesIn Vitro

Topalović

Živković

Čabarkapa

et al. 2015

Oxidative Medicine and Cellular Longevity

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The thyroid hormones change the rate of basal metabolism, modulating the consumption of oxygen and causing production of reactive oxygen species, which leads to the development of oxidative stress and DNA strand breaks. Olive (Olea europaea L.) leaf contains many potentially bioactive compounds, making it one of the most potent natural antioxidants. The objective of this study was to evaluate the genotoxicity of L-thyroxine and to investigate antioxidative and antigenotoxic potential of the standardized oleuropein-rich dry olive leaf extract (DOLE) against hydrogen peroxide and L-thyroxine-induced DNA damage in human peripheral blood leukocytes by using the comet assay. Various concentrations of the extract were tested with both DNA damage inducers, under two different experimental conditions, pretreatment and posttreatment. Results indicate that L-thyroxine exhibited genotoxic effect and that DOLE displayed protective effect against thyroxine-induced genotoxicity. The number of cells with DNA damage, was significantly reduced, in both pretreated and posttreated samples (P < 0.05). Comparing the beneficial effect of all tested concentrations of DOLE, in both experimental protocols, it appears that extract was more effective in reducing DNA damage in the pretreatment, exhibiting protective role against L-thyroxine effect. This feature of DOLE can be explained by its capacity to act as potent free radical scavenger.

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Evaluation of the effects of ephedrine on human lymphocytes in the comet assay

Radaković¹,

Djelić²,

Stanimirović³

et al. 2011

Acta vet. (Beogr.)

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Ephedrine, a natural alkaloid from plants of the genus Ephedra, has a chemical structure similar to catecholamines. It is well established that catecholamines (adraneline, noradrenaline and dopamine) cause genotoxic and mutagenic effects. Therefore, the objectives of this investigation were to examine weather ephedrine can exhibit genotoxic effects on isolated human lymphocytes in the Comet assay. Dose-response of human lymphocytes was determined at the concentration range of ephedrine from 0.0005 μM to 500 μM. Three concentrations of ephedrine (1, 50 and 300 μM) which had acceptable cell viability (over 90%) were used for further experiments with inhibitors of DNA reparation (cytosine arabinoside and hydroxyurea). The obtained results showed that ephedrine did not induce DNA damage in isolated human lymphocytes. However, co-treatment of the negative control with DNA repair inhibitors caused a slight but significant increase of DNA damage, due to an endogenous DNA damage. Interestingly, cells treated with ephedrine and DNA repair inhibitors did not express increased DNA damage. On the basis of the obtained results it can be concluded that ephedrine did not exhibit genotoxic effects on isolated human lymphocytes. This result is in accordance with previous investigations showing negative genotoxicological results for ephedrine using bacterial gene mutation test-systems and in vitro cytogenetic analysis

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Evaluation of the genotoxic effects of thyroxine using in vivo cytogenetic test on Swiss albino mice

Cited by 4 publications

References 29 publications

Effect of l-Thyroxine on Micronuclei Frequency in Peripheral Blood Lymphocytes in Clinical and Experimental Conditions

Effect of l-Thyroxine on Micronuclei Frequency in Peripheral Blood Lymphocytes in Clinical and Experimental Conditions

Dry Olive Leaf Extract Counteracts L-Thyroxine-Induced Genotoxicity in Human Peripheral Blood LeukocytesIn Vitro

Evaluation of the effects of ephedrine on human lymphocytes in the comet assay

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