Study of the 6-propyl-2-thiouracil (PTU) as a Radioprotector for the Thyroid Gland.

PERONA, M; DAGROSA, MA; PAGOTTO, R; CASAL, M; PIGNATARO, O; PISAREV, M; JUVENAL, GJ

Gramado, Brasil

Congreso; XIII Congreso Sociedad Latinoamericana de Tiroides Congreso; 2009

Sociedad Latinoamericana de Tiroides

Introduction: epidemiologic studies have shown that the exposition to high external radiation doses increases thyroid neoplastic frequency, especially when given during childhood or adolescence. The use of radioprotectors, drugs that protect cells from the damage caused by radiation therapy, could be useful to prevent the development of thyroid tumors in patients treated with this therapy. Objective: To study the effect of propylthiouracil as a radioprotector in the thyroid gland. Methods: FRTL-5 cells were exposed to ã-irradiation at different doses (1 to 8 Gy) in the presence or absence of PTU (0.5 and 1mM). Cell surviving fractions (SF) were determined by the standard in vitro colony formation assay. Results: Cell viability was evaluated by MTT assay. PTU didn’t affect the viability “per se”. The SF was increased in the presence of PTU, in both concentrations. The ratio PTU vs control (5Gy) was 1.3 and 1.5 respectively. cAMP levels were measured after incubating the cellular line with different concentrations of PTU (0; 0.1 mM; 0.5 mM) at different times (5, 24, 48 and 72 hours). A peak was observed at 24 hs in extracelullar levels when cells were incubated with PTU 0.5 mM (52.67 ± 5.55 fmol/µg prot vs control: 41.91 ± 6.01 fmol/µg prot). Catalase activity was increased in irradiated cells (1 and 5 Gy) treated with PTU. Conclusion: PTU is a radioprotector for thyroid cells and could exert its effect through cAMP increasing the activity of antioxidant enzymes.