Evaluation of neurotoxic effect of synthetic pyrethroids: comparative characteristics of neurotoxic action of cypermethrin and zeta-cypermethrin in pre- and postnatal period

Abstract

Synthetic pyrethroids (SPs) are insecticides used in everyday life, in rural and forestry farms. The wide use of SPs is due to their ability to rapidly biodegradate, relatively low toxicity to mammals and high insecticidal activity. Due to the similarity of neurochemical processes, these compounds may also exhibit their neurotoxic properties in non-target objects, in addition to the effects on pests. An overview ofscientific literature has shown that the best biological model for investigating the potential neurotoxic effects of SPs and extrapolation of obtained experimental data to humans is the rat. Objective — to investigate the effect of cypermethrin and zeta-cypermethrin in pre- and postnatal development; to conduct a comparative study of the neurotoxic properties of cypermethrin and zeta-cypermethrin. Methods —the article presents the data of two conducted experiments studying the neurotoxic activity of representatives ofpyrethroid insecticides — cypermethrin and zeta-cypermethrin. Results — it was found that cypermethrin and zeta-cypermethrin exhibit gender-related sensitivity: young male rats were more susceptible to cypermethrin and zeta-cypermethrin compared to females. The effect of cypermethrin and zeta-cypermethrin in the pre-and postnatal period is dose-dependent. Effect of cypermethrin in doses of 17,5 and 35 mg/kg and zeta-cypermethrin at a dose of 12,5 mg/kg in the pre- and postnatal period does not cause a neurotoxic effect in offspring. Cypermethrin exposure at a dose of 70 mg/ kg and zeta-cypermethrin exposure in doses of 35 and 70 mg/kg causes changes in behavioural reactions of offspring of both genders. Administration of cypermethrin at a dose of 70 mg/kg in the- pre and postnatal period affects motor activity and cognitive activity of young male rats (in terms of increasing the latent period of the first movement and decreasing the number of crossed squares). Administration of zeta-cypermethrin at a dose of 70 mg/kg causes in the offspring of both genders disorders in the psycho-emotional state (decrease in the parameters of the grooming), inhibition of motor and cognitive activity (decrease of the number of crossed squares and pointing for males, decrease of the number of crossed squares for females), and reduction of adaptive properties (increase of latent period of the first movement for males). Under the action of zeta-cypermethrin at a dose of 35 mg/kg in males, an increase in anxiety was observed (decrease in the total duration of the grooming). Zeta-cypermethrin showed a greater neurotoxicity on offspring compared with cypermethrin. Key words: pesticides, synthetic pyrethroids, cypermethrin, zeta-cypermethrin, nervous system, prenatal period, postnatal period, behavioural reactions.