Effect of vitamin- E on cypermethrin induced toxicity in cerebral cortex of wistar albino rats: A histological study

Backgrounds: Cypermethrin, class II pyrethroid pesticides, is commonly used in the agricultural field and house pest controls. Cypermethrin leads to neurotoxicity by crossing the blood-brain barrier, inducing oxygen stress in brain tissue. Vitamin-E is an antioxidant, involving in protecting membrane stability against free radicals induced peroxidants. This study was conducted to see the protective effect of vitamin-E on cypermethrin induced toxicity. Methodology: Fifty healthy Wistar albino rats of either sex weighing 150-200 grams were randomly selected & divided into five groups. Rats in first group served as control. Rats in second and fourth group were given cypermethrin orally at 20 mg/kg/BW for 14 and 28 days respectively. Rats in third and fifth group were give cypermethrin plus vitamin-E 2.5 ml/kg/BW orally for 14 and 28 days respectively. Rats were sacrificed and the brain was removed. Tissue processing was done. Histological analysis was carried out and statistical analysis was performed by the use of SPSS. Result: Cypermethrin treated rats showed decreased body and brain weight with severe neuronal vacuolation and decrease glial cell. While cypermethrin plus vitamin-E treated group showed increased body and brain weight, with normal glial cell and mild neuronal changes were observed. Conclusion: Cypermethrin in combination with vitamin-E minimized its harmful effect which was evidenced by improving body and brain weight gain and histological changes.

Cypermethrin is commonly used synthetic pesticide globally, 1 to control agricultural and household insect pests. 2 Use of cypermethrin in modern agriculture for eradication of rodents, insect 3 has posed potential hazards to all living creatures. 4 It is easily available in local market in the form of concentrate in suspension or mixed with other insecticide. 5 Cypermethrin has be identified as important group of pesticides associated with human health risk. 6,7 Cypermethrin crosses blood brain barrier, inducing free radicals generation which can lead to neurotoxicity in central nervous system. [8][9][10][11][12] Exposure to cypermethrin may show complex syndrome including seizure, numbness, tingling sensation due to dermal exposure. 13 Cypermethrin involve gene expression, 14 reproductive toxicity 15 and immunotoxic effects. 16 Vitamin-E act as an antioxidant 17,18 against free radicals induced. This study aims to observe the histological changes in extent to different exposed periods and to find out the protective effect of vitamin-E on toxic changes caused by cypermethrin. The data on the body weight of different groups at different time frames are summarized in the Table-1 and Table-2  The symbol * indicates paired-t test between the mean body weight before and after the experiment and symbol ** indicates ANOVA between mean group weights before and after the experiment. The symbol * indicates paired-t test between the mean body weight before and after the experiment and symbol ** indicates ANOVA between mean group weights before and after the experiment.

MATERIALS & METHODS
In 14 days experiment group, the mean brain weights were 1.54±0.02, 1.53±0.05 and 1.55±0.01 gram in groups one, two and four respectively. Similarly in 28 days, the mean brain weights were  The symbol * and ** indicates ANOVA between the groups and within a group at different time frames respectively.  In this study it was found that the brain weight of rats treated with cypermethrin for longer duration showed decrease in brain weight. But when vitamin-E was given along with cypermethrin with similar duration showed increase in brain weight in comparison with cypermethrin alone treated group for longer duration. The improvement in the brain weight is probably due to the antioxidant property. Elblehi 21 who reported that histopathological examinations of rat's brain in cypermethrin with vitamin-E treated group showed mild lesion, which was seen as neuronal vacuolation.

Limitation of this study
We have used simple compound microscope with no camera attached so the histological picture taken was not clear as expected. Ultrathin slice of the tissue could not be obtained because of the rotatory machine available.
Less number of sample size was considered.

CONCLUSION
Cypermethrin can induced neurotoxicity and histological changes in brain and is a major concern for human. Since these pesticide are widely used in agricultural field, care must be taken in handling both at home and in work place, as prolonged exposure leads to adverse health effects. Using Vitamin-E in cypermethrin exposed can minimized its toxic effect. Furthermore, restricted sale of these chemicals, user awareness, and avoidance of food contaminated with pesticide and vitamin E rich diet could be beneficial to prevent cypermethrin toxicity.

Acknowledgement
I will like to express my sincere gratitude to Dr Manisha Jha, Saru Bhattarai and