Differential effects of azinphos-methyl and chlorpyrifos on polyamine oxidative metabolism during the embryonic development of Rhinella arenarum and its relation to oxidative stress.
Pires, N., Maiale, S., Venturino, A. and Lascano, C.
Centro de Investigaciones en Toxicologia Ambiental y Agrobiotecnologia del Comahue (CITAAC), Universidad Nacional del Comahue-Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET). Buenos Aires 1400, 8300 Neuquen, Neuquen, Argentina; Facultad de Ciencias Medicas, Universidad Nacional del Comahue. Toschi y Arrayanes, 8324 Cipolletti, Rio Negro, Argentina.
Instituto Tecnologico Chascomus, Universidad Nacional de General San Martin-Consejo Nacional de Investigaciones Cientificas y Tecnicas (INTECH/UNSAM-CONICET). Av. Intendente Marino, Km 8, 200 CC 164, 7130 Chascomus, Buenos Aires, Argentina.
Centro de Investigaciones en Toxicologia Ambiental y Agrobiotecnologia del Comahue (CITAAC), Universidad Nacional del Comahue-Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET). Buenos Aires 1400, 8300 Neuquen, Neuquen, Argentina; Facultad de Ciencias Agrarias, Universidad Nacional del Comahue. Ruta 151, Km 12,5, 8303 Cinco Saltos, Rio Negro, Argentina.
Centro de Investigaciones en Toxicologia Ambiental y Agrobiotecnologia del Comahue (CITAAC), Universidad Nacional del Comahue-Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET). Buenos Aires 1400, 8300 Neuquen, Neuquen, Argentina; Facultad de Ciencias Agrarias, Universidad Nacional del Comahue. Ruta 151, Km 12,5, 8303 Cinco Saltos, Rio Negro, Argentina. Electronic address: cecilia.lascano@faca.uncoma.edu.ar.
The organophosphorus pesticides azinphos-methyl (AZM) and chlorpyrifos (CPF) exert their toxic action by inhibition of acetylcholinesterase, but non-target processes such as polyamine metabolism can also be affected. Our objective was to evaluate the effects of different concentrations of AZM (0.5-, 2- and 9mgL(-)(1)) and CPF (0.5- and 1mgL(-)(1)) on polyamine oxidative metabolism along Rhinella arenarum embryonic development and to explore its relationship to oxidative stress. Free and conjugated polyamines were measured by HPLC. The activity of spermine oxidase (SMOX), N(1)-acetylpolyamine oxidase (PAOX) and diamine oxidase (DAO) were measured through kinetic spectrofluorometry. Free putrescine and spermine were significantly increased in open mouth embryos exposed to AZM. Free polyamine levels were not affected by CPF exposure. In embryos exposed to AZM, DAO was increased in tail bud stage and SMOX was increased in open mouth stage, while embryos exposed to CPF showed an increase of PAOX activity in tail bud stage and a decrease of DAO and SMOX activity in open mouth stage. Polyamine levels and oxidative degradation enzymes respond differently if R. arenarum embryos are exposed to AZM or CPF, despite that both insecticides belong to the same chemical family. The early increase of DAO and PAOX would play a protective role to guarantee the normal progression of embryonic development. The increased production of reactive species might contribute to an oxidative stress situation generated by exposure to the insecticides and to the alteration of the antioxidant defense system. In tail bud stage embryos, PAOX and SMOX were positively correlated to acetylcholinesterase activity and reduced glutathione levels (GSH), and negatively correlated to the antioxidant enzymes catalase (CAT) and glutathione S-transferase (GST). In complete operculum embryos, a negative correlation between antioxidant parameters and polyamine levels and polyamine oxidative metabolism was observed, except for SMOX, which showed a low positive correlation with CAT and GSH and a negative correlation to PAOX and DAO. We suggest the use of DAO and PAOX as biomarkers of exposure to AZM and CPF, respectively, as they respond earlier than the classical biomarker acetylcholinesterase.
Pesticide Biochemistry and Physiology 163: 14-22 (2020)