Asari, Mohd Asnizam and Ismail, Zul lzhar Mohd and Mansor, Othman
(2009)
The effect of early postnatal exposure to pyrethroid
(deltamethrin) and pyrethroid-based mosquito repellent
on the cerebellum of rats.
The effect of early postnatal exposure to pyrethroid (deltamethrin) and pyrethroid-based mosquito repellent on the cerebellum of rats.
Abstract
Deltamethrin is a widely used type II pyrethroid-based insecticide. Studies
indicated that neonatal exposure to deltamethrin even at relatively low dose
resulted in behavioral and neurological changes. In the present study, the effect
of early neonatal exposure to low dose deltamethrin on the histogenesis of the
cerebellar cortex was investigated. Sprague Dawley male pups were exposed
to deltamethrin in a dose of 1 mg/kg/day via intraperitoneal injection from 2"d to
5lh postnatal day and sacrificed on postnatal day 6, 14 and 21. The cerebellum
was removed, processed, embedded with paraffin wax and serially sectioned.
Cerebelar tissue sections were stained with Harris hematoxylin and eosin and
anti-synaptophysin immunohistochemistry. The thickness of the different layers
of the cerebellar cortex and the optical density of the molecular layer were
measured using Image Proplus software. The results showed no differences in
the measured thickness of the external granular, molecular and internal
granular layers between the deltamethrin-treated and the control animals in all
age groups studied. There were significant upregulation of the synaptophysin
immunoreactivity in the molecular layer when examined at postnatal day 6, but
not at postnatal day 14 and 21. In conclusion, the present study showed that
neonatal administration of the deltamethrin at the current dosage did not
significantly affect the morphogenesis of the cerebellar cortex.
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