Histopathological Changes in the Brain, Heart and Lungs of Wistar Rats Exposed to Sub-Lethal Dose of a Locally Formulated Pesticide Ota-Piapia

This study presented histopathological changes in the brain, heart and lungs of Wistar rats exposed to sub-lethal doses of a local pesticide Ota-piapiaused to control mosquitoes in Nigeria. A total of 24 rats of both sexes weighing between 180-200g were used for this study. The rats were acclimatized for four weeks, fed twice daily and water givenadlibitum. After acclimatization, the rats were randomly divided into four groups; 1, 2, 3, and 4, with six rats per group. Group1 served as control with no treatment administered. Rats in groups 2, 3 and 4 were exposed to 5 ml, 8 ml and 10ml sub-lethal doses (for 4 hours) of Ota-piapiarespectively for twelve weeks at interval of three days. Twelve of the rats were kept for additional four weeks after ceasation of exposure. Twenty four hours after the last exposure, the animals were anesthetized using chloroform and euthanized by cervical dislocation. Sections of the brain, heart and lungs were harvestedin 10 % buffered neutral formalin and processed for histopathology. Result revealed congestion, necrosis of neurons and vacuolation in brain; congestion, haemorrhage and necrosis of cardiac muscle fibres. In the lung, there were thickened inter-alveolar walls, massive infiltration of the bronchiole by inflammatory cells, congestion and haemorrhages. There were no significant observable differencesin the histopathological findings in the animals kept for the additional four weeks without treatment. Therefore, it was concluded that locally formulated Ota-piapiapesticides are hazardous to the health of the test animals and the use of insecticides treated mosquito nets should be used rather than pesticides.

Keywords: Histopathological changes, sub-lethal,Ota-piapia, congestion, haemorrhage.