Suceptibility of early stages of Bufo arenarum embryos to photodynamic therapy whit methylene blue (AM).

LOPEZ, V ; PAISIO, C,; BERTUZZI, M, ; RIVAROLA, V

Villa Giardino, Córdoba,

Congreso; Villa Giardino, Córdoba,; 2005

SBC

The photodynamic therapy is an antineoplasic treatment in which a photosensitizer, oxygen and visible light are involved. It is important to investigate the toxic activity of new photosensitizer to know their reach and limitations as potential therapeutic compounds. The aim of this work was to evaluate the different susceptibility of Bufo arenarum embryos stages to the photosensitizer AM, standardizing an embryotoxic test. Embryos in gastrula, bud fin back and open mouth stages were used. The CL50 values and malformation in darkness and the phototoxic CL50 (irradiation 30 min.) were obtained beginning from the maximum no-toxic dose in darkness. For 24 h of exposure to AM+ in darkness, the CL50 were 2 and 1,2 mM to gastrula and open mouth stages respectively. Bud fin back couldn?t be measured because the high density of the environment exceeded viability. This stage was exposed to 36 and 48 h. obtaining the CL50 of 713 and 120 μM respectively. The malformation occurred in all the tested embryonic stages. The more frequent were incurvated axis and general edema. In the light test, for 24 h. of incubation gastrula and open mouth CL50 were 760 and 50 μM; and for 36 and 48 h. in bud fin back were 60 and 20 μM respectively. The results indicate that AM+ and visible light combination is responsible for embryos death while the drug in darkness caused malformation at all developmental stages evaluated. The sensibility is related to the developing stage and the drug time exposition. This experimental model could be adapted to lethal and teratogenic tests with new photosensitizing drugs studied in PTD.