Teratogenicity and Embryotoxicity of two Commonly used Insecticides in MICE

Abstract

The purpose of this study was to asses s the embryotoxic and teratogenic potential of Smithion, an organophosphate insecticide and Furadan, a carbamate insecticide in mice. 1) Toxicity of both the insecticides was determined by the administration of wide range of doses of these insecticides to the pregnant mice on gestational day (GD) 6. The LD50 values of Sumithion and Furadan were calculated as 298 μg/gBW and 158 μg/gBW, respectively. 2) The treated mothers showed various signs of behavioural deviation, following exposure to the both the insecticides. Profuse oral and nasal secretions were observed in both single as well as triple dose groups of Sumithion. Animals exposed to furadan showed signs of poisoning such as shivering, reduced activity, which led to respiratory failure. 3) The results of morphometric studies revealed that both the insecticides affected various morphometric parameters negatively. I. The average crown-rump length and average body weight of the fetuses decreased with the increasing each dose concentration of Sumithion and Furadan. A significant dose dependent decrease in fetal crown ramp length and body weight was evident in high dose of both the insecticides. II. Significant decrease in size of fetal brain, eye, ear, snout, fore limb, hind limbs and tail was observed in doses of 74.5 to 298 μg/gBW of Sumithion. In case of Furadan, a significant decrease in the size fetal brain, eye, ear, snout, fore and hind limb was more evident in 39.50 to 158 μg/gBW dose groups as compared to the control. 4) Morphological examination of the fetuses under stereoscopic research microscope further supported the above-mentioned observations. The development of brain, craniofacial organs and limbs was affected negatively in the various dose group of sumithion and Furadan. In many cases, there was no distinction between fore, mid and hind limbs were rudimentary with incomplete digitation in most the fetuses, however, the number of fetuses malformed per litter increased to doses of 149 to 298 μg/gBW of Sumithion and 79 to 158 μg/gBW of Furadan. 5) Histological studies confirmed the malformations observed in morphological analysis. I. Brain: Distinct atrophy of cells in the walls of brain was observed. Development of eyes was affected and nasal chamber was malformed in most of the fetuses exposed to Sumithion. Fetuses were poorly formed in the various dose groups of Furadan. Ventricles of brain, eye, ear and nasal chamber were also poorly developed and atrophied in many cases. II. Heart: The valves of the heart were atrophied in the fetuses exposed to Sumithion. Ventricular wall was poorly developed and lacked muscle content in most of the fetuses. Ventricular septal defects and severe necrosis in the walls of heart were the main malformations observed in the fetuses exposed to Furadan. III. Liver: In case of Sumithion, degeneration and necrosis of parenchymal cells of liver was the main hepatotoxic effect. The development of liver was affected negatively. There appeared breakdown in the endothelial lining of the hepatic sinuses. Severe vacuolation in cytoplasm a pyknosis of nuclei was observed in different dose groups of Furadan. IV. Limbs: Fore and hind limbs were poorly developed in case of various dose groups of Sumithion. Bone formation was affected to a great extent. Digitation was incomplete. extra digit (Polydactyly) was observed consistently in fetuses exposed to various doses of Sumithion. Fetal limbs in one of the higher dose group of Furadan lacked any digital differentiation; there was no sign of digitation or bone formation. 6) The histological studies on maternal liver showed various degenerative changes which indicted the toxicity of insecticides. A considerable degree of vacuolation and distension of blood vessels was observed in the liver of different mothers exposed to Sumithion and Furadan. 7) Following exposure to sumithion and Furadan, the percentage absorbed or dead fetuses increased in dose related manner. The histological analysis of these fetuses clearly indicated the presence of embryonic body remnants within a highly vascularized uterine cavity.