Author(s): Gupta A, Nigam D, Gupta A, Shukla GS, Agarwal AK
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Abstract Pesticides have been implicated in various neurological disorders in humans and experimental animals. Our earlier studies have demonstrated a high vulnerability of developing blood-brain barrier (BBB) towards very low level exposure of quinalphos, cypermethrin and lindane. Earlier it has been observed that a cypermethrin-induced increase in the BBB permeability of neonatal rats was found to be persistent, requiring a longer period of withdrawal for complete recovery. These observations lead us to investigate the effect of a commonly available liquid mosquito repellent (MR) containing a pyrethroid compound, allethrin (3.6\% w/v), on the functional integrity of the developing BBB and on certain parameters of oxidative damage in brain, liver and kidney. Two-day-old rat pups were allowed to inhale the MR (18 h per day) for 8 days (postnatal days (PND) 2-9). Rats exposed to MR were further withdrawn from the exposure for 8 days (PND 10-17) to study whether the changes induced following inhalation are reversible. Results of the study have shown a significant increase in the BBB permeability (45\%) of the MR-exposed rat pups to a micromolecular tracer, sodium fluorescein (mol. wt. 376), used for the quantitative assessment of the BBB permeability, suggesting a delayed maturity of the BBB system. Brain glutathione (GSH) levels were also decreased (17\%) in the exposed individuals. The oxidatively damaged end-products of lipids, measured as lipid hydroperoxides and conjugated dienes, were found to be increased in brain (42\%, 16\%), liver (34\%, 20\%) and kidney (68\%, 29\%), respectively. The oxidative product of protein, measured as protein carbonyls, was also increased significantly in liver (43\%) and kidney (16\%) of the MR-exposed rat pups as compared to age-matched controls. The biochemical changes that occurred in the BBB permeability and the oxidatively damaged end-products following MR inhalation in neonatal rats were, however, found to be completely recovered except for an increase in brain GSH (28\%) level. The results suggest the possibility of health risk due to exposure to pesticide-based mosquito repellents, especially when exposure takes place in individuals at an early age.
This article was published in J Appl Toxicol
and referenced in Journal of Veterinary Science & Technology