Kasim, Fazlina
(2010)
The effects of acute malathion
exposure on the cerebellum of female
rats
The effects of acute malathion
exposure on the cerebellum of female
rats.
Masters thesis, Universiti Sains Malaysia.
Abstract
Malathion is an organophosphate pesticide which is used for agricultural pest
control and dengue control in Malaysia. As pesticides use is on the rise to augment
agricultural productivity in Malaysia, there is also evidence of an increasing trend of
pesticide poisoning. Malathion irreversibly inhibits acetylcholinesterase resulting in an
impairment of numerous body functions. Even though there is sufficient information
about the neurotoxicity of organophosphates , there is limited information on the effects
of malathion on the cerebellum. This study is conducted to determine the effects of acute
malathion exposure on the estimated total number ofPurkinje cells; and the thickness of
the granular and molecular layers in the cerebellum of rats. Ten adult female Wistar rats
were administered 250 mg/kg intraperitoneal malathion (corresponding to 0.2 of
malathion's LD50) daily for seven consecutive days. In the control group, ten rats
received equivalent volumes of 0.9% sodium chloride instead. Body weight was
monitored daily. Twenty-four hours after the seventh dose of malathion, the rats were
sacrificed and their cerebellum taken for analyses. Each cerebellum was sampled
systematically and randomly by applying the fractionator method and stained with cresyl
fast violet. Subsequently, Purkinje cells nucleoli were counted to obtain an estimation of
the total number of Purkinje cells in each cerebellum. The thicknesses of the granular
and molecular layers were measured using an image analyser. Data obtained were analysed using the Statistical Package for Social Science, version 12. Rats exposed to
malathion showed significant deficits in body weight compared to rats in the control
group (t = 4.27, p < 0.001 ). There is no statistically significant difference in the
estimated total number of Purkinje cells between the malathion-exposed group and the
control group. The thickness of the granular and molecular layers was also not
significantly different between the two groups. It is concluded that the dose of malathion
used in this experiment did not have any significant effect on the total numbers of
Purkinje cells and the thickness of the granular and molecular layers in the cerebellum of
rats. Further studies on the effects of malathion on the cerebellum will be conducted by
applying a higher dose of malathion or a longer duration of malathion exposure.
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