Hyperthyreosis effects on the learning and glial intermediate filaments of rat brain
AbstractThe influence of hyperthyreosis on oxidative stress, state of glial intermediate filaments and memotry was investigated. Significant increasing of lipid peroxidation products into both hippocampus and cortex and change for the worse of memory was observed. Analysis of the behavioral reactions of rats in the test of passive avoidance conditioned reflex showed that the acquisition of skills of all groups of animals did not differ by time waiting period (latent period). Time saving memory test conditioned reflex of passive avoidance was excellent in the group of rats treated with thyroxine compared with controls. The change of polypeptide GFAP was observed in hippocampus and cortex. Both soluble and filamentous forms of GFAP increased in hippocampus of rat with hyperthyreosis. In filament fractions, increase in the intensity of 49 kDa polypeptide band was found. In the same fraction of insoluble cytoskeleton proteins degraded HFKB polypeptides with molecular weight in the region of 46–41 kDa appeared. Marked increase of degraded polypeptides was found in the soluble fraction of the brain stem. The intensity of the intact polypeptide (49 kDa), as well as in the filament fraction, significantly increased. It is possible that increasing concentrations of soluble subunits glial filaments may be due to dissociation of own filaments during the reorganization of cytoskeleton structures. Given the results of Western blotting for filament fraction, increased content of soluble intact 49 kDa polypeptide is primarily the result of increased expression of HFKB and only partly due to redistribution of existing filament structures. Calculation and analysis of indicators showed high correlation between the increase in content and peroxidation products of HFKB. These results indicate the important role of oxidative stress in the induction of astroglial reactive response under conditions of hyperthyroidism. This data shows the possibility of the glial cell cytoskeleton reconstruction under effect of thyroid hormones.
Andres-Barquin, P.J., Fages, C., Le Prince, G., Rolland, B., Tardy, M., 1994. Thyroid hormones influence the astroglial plasticity: Changes in the expression of glial fibrillary acidic protein (GFAP) and of its encoding message. Neurochem. Res. 19(1), 65–69.
Baydas, G., Koz, S.T., Tuzcu, M., Etem, E., Nedzvetsky, V.S., 2007. Melatonin inhibits oxidative stress and apoptosis in fetal brains of hyperhomocysteinemic rat dams. J. Pineal. Res. 43(3), 225–231.
Baydas, G., Donder, E., Kiliboz, M., Sonkaya, E., Tuzcu, M., Yasar, A., Nedzvetskii, V.S., 2004. Neuroprotection by α-lipoic acid in streptozotocin-induced diabetes. Biochem. (Mosc.) 69(9), 1233–1238.
Bernal, J., 2005. Thyroid hormones and brain development. Vitam. Horm. 71, 95–122.
Bernal, J., 2007. Thyroid hormone receptors in brain development and function. Nat. Clin. Pract. Endocrinol. Metab. 3(3), 249–259.
Bernal, J., Nunez, J., 1995. Thyroid hormones and brain development. Europ. J. Endocrinol. 133(4), 390–398.
Eng, L.F., Ghirnikar, R.S., Lee, Y.L., 2000. Glial fibrillary acidic protein: GFAP-thirty-one years (1969–2000). Neurochem. Res. 25(9), 1439–1451.
Farvell, K., Tranter, C., Leonard, J.L., 1995. Thyroxin-edependent regulation of integrin-laminin interaction in astrocytes. Endocrinology 136(9), 3909–3915.
Haddad, F., Arnold, K., Zeng, M., Boldwin, K., 1997. Interaction of thyroid state and denervation on skeletal myosin heavy chain expression. Muscle Nerve 20(12), 1487–1496.
Hattori, F., Oikawa, S., 2007. Peroxiredoxins in the central nervous system. Subcell. Biochem. 44, 357–374.
Miller, G.L., 1959. Protein determination for large numbers of samples. Anal. Chem. 31(5), 964–966.
Motomura, K., Brent, G.A., 1998. Thyreotoxicosis. Endocrinol. Metab. Clin. North Am. 27(1), 1–23.
Nedzvetskii, V.S., Tuzcu, M., Yasar, A., Tikhomirov, A.A., Baydas, G., 2006. Effects of vitamin E against aluminum neurotoxisity in rats. Biochem. (Mosc.) 71(3), 239–244.
Nunez, J., 1985. Microtubules and brain development: The effects of thyroid hormones. Neurochem. Int. 7(6), 959–968.
Nunez, J., Couchie, D., Aniello, F., Bridoux, A.M., 1992. Thyroid hormone effects on neuronal differentiation during brain development. Acta Med. Austriaca. 19(1), 36–39.
Trentin, A.G., De Aguiar, C.B., Garcez, R.C., Alvarez-Silva, M., 2003. Thyroid hormone modulates the extracellular matrix organization and expression in cerebellar astrocyte: Effects on astrocyte adhesion. Glia 42(4), 359–369.
Venero, C., Herrero, A.I., Touyarot, K., Cambon, K., Lopez-Fernandez, M.A., Berezin, V., Bock, E., Sandi, C., 2006. Hippocampal up-regulation of NCAM expression and polysialylation plays a key role on spatial memory. Eur. J. Neurosci. 23(6), 1585–1595.
Zamoner, A., Funchal, C., Jacques-Silva, M.C., Gottfried, C., Barreto Silva, F.R., Pessoa-Pureur, R., 2007. Thyroid hormones reorganize the cytoskeleton of glial cells through Gfap phosphorylation and Rhoa-dependent mechanisms. Cell Mol. Neurobiol. 27(7), 845–865.
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