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Título

POSSIBLE RELATIONSHIP BETWEEN PRENATAL EXPOSURE TO THE LARVICIDE PYRIPROXYFEN AND DEFICITS IN MOTOR FUNCTION AND IN TIBIALIS ANTERIOR MUSCLE STRUCTURE IN RATS

Resumo

INTRODUCTION: Pyriproxyfen is a pesticide used in Brazil to control the Aedes aegypt mosquitoes. However, this pesticide has a similar molecular structure to the retinoic acid, a vitamin A derivative that regulates neurogenesis, skeletal striated muscle development and expression of myogenic specification genes. In this sense, it is postulated that exposure of pregnant women to this larvicide could interfere with retinoic acid signaling, impairing the motor function and muscle tissue structure. OBJECTIVE: This study aimed to verify if the prenatal exposition to pyriproxyfen can produce motor deficits, as well as damage to the muscular tissue of the offspring. METHODS: Male Wistar rat pups were divided in 3 groups: Negative control (CT-) - offspring of mothers who drunk water during pregnancy; Positive control (CT+) - offspring of mothers who drunk water containing 2 g/L of vitamin A during pregnancy and Pyriproxyfen (PIR) - offspring of mothers who drunk water containing 0.002 g/L of Sumilarv during pregnancy, a pesticide that uses pyriproxyfen as the active ingredient. The gait quality of the experimental animals was evaluated using Basso, Beattie and Bresnahan scale (1996). On the 40th postnatal day, animals were euthanized and the tibialis anterior muscle was dissected. Samples were stained with hematoxylin and eosin for analysis of the peripheral nucleus/muscle fiber ratio, capillary/muscle fiber ratio and cross-sectional area of muscle fibers. RESULTS: In one animal from the PIR and one from the CT+ group it was observed external rotation of the hindlimbs. Deficits in motor coordination were also observed in one animal from the PIR and in four animals from the CT+ group. However, the BBB score was similar between CT-, CT+ and PIR groups. The peripheral nucleus/muscle fiber ratio and cross-sectional area of muscle fibers was also similar in the three experimental groups studied. On the other hand, capillary/muscle fiber ratio was lower in the CT+ and PIR compared to the CT- group. CONCLUSION: The motor and structure damage of the muscle observed in this study were subtle, which may be related to the administration of pyriproxyfen and retinoic acid having been performed on demand. This method of administration was used to mimic what occurs when pyriproxyfen is added to drinking water tanks to control the Aedes Aegypt. More studies are needed to confirm whether maternal exposure to pyriproxyfen produces more severe deleterious effects on the offspring.

Palavras Chave

Teratogenesis; Gait; Tibialis anterior muscle