الفهرس 
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Abstract
Excessive use of malathion as an organophosphorus pesticide without control induces toxicological effects on animals and the environment, hence it is crucial to evaluate its effects, especially after chronic exposure.
The current study was designed to evaluate the efficacy of Selenium nanoparticles on Malathion on the male reproductive system of adult Sprague Dawley rats through assessment of body weight, testes and epididymis weight, oxidative stress activity, hormonal levels, epididmal sperm parameters, and histopathological changes in testes.
Forty adult mature male Sprague Dawley rats were divided into four groups (10 rats each). G1 was without any treatment just take 0.2 ml/kg of corn oil as a control for 8 weeks, G2 exposed to Malathion 27 mg/kg body weight (1/50 LD50) with stomach gavage 2-3 times weekly for 8 weeks, G3 exposed to low effective dose of Selenium Nanoparticles 0.4 mg/kg body weight before taken Malathion at dose of 27 mg/kg body weight with stomach gavage 2-3 times weekly for 8 weeks and G4 exposed to high effective dose of Selenium Nanoparticles 4.0 mg/kg body weight before taking malathion at dose of 27 mg/kg body weight with stomach gavage 2-3 times weekly for 8 weeks.
Blood samples were collected from the medial canthus of the orbital cavity of rats in vacutainer tubes without anticoagulant to obtain serum after centrifugation at 4500 rpm for 30 minutes for hormonal estimation. Rats were scarified by cervical dislocation for tissue sample collection. Testes were collected from each rat. The left one was used for evaluation histopathological changes, while the right testis was preserved at -20 ºC after scarification for homogenate preparation for measuring oxidative stress and enzyme activity. The epididymis was incised with a sharp scalpel to examine the sperm parameters.
The obtained results showed a significant increase (p ≤0.05) in the body weight of rats in G4 in comparison with G1 and other treatment groups. While there was a nonsignificant difference in absolute and relative testes weight in all groups.
Testosterone hormone in the serum of adult male rats showed a significant decrease (p ≤0.05) in G2 and G3 in comparison with G1 and other treatment groups. While the level of testosterone in G4 was higher than in G1.
LH levels showed a significant decrease (p ≤0.05) in G2 and G3 in comparison with G1 and G4, while non-significant differences were observed between the G1 and G4 groups.
FSH levels showed a significant decrease (p ≤0.05) in all treatment groups in comparison with G1.
ACP in testis homogenate showed a non-significant difference (p ≤0.05) between G1 and other treatment groups, while a significant decrease was observed between G2 and G3 in comparison with G4.
GPx in testicular tissue showed a highly significant decrease in all treatment groups in comparison with control groups.
GSH in testicular tissue showed a significantly higher (p ≤0.05) level in G4 than in G1, while showing a highly significant decrease between G2 and G3 in comparison with G1 and G4.
SOD activity in testicular tissue showed a highly significant decrease in G1 in comparison with other treatment groups.
MDA level in testicular tissue showed a highly significant increase (p≤0.05) in G2 in comparison with G1 and other treatment groups.
Sperm counts showed a significant decrease (p ≤0.05) in G2 compared to G1, while they showed a significant increase in G4 compared to G1.
The percentage of sperm abnormality showed a significant increase (p≤0.05) in G2 in comparison with the G1 group, while there was a no significant difference between G1 and G3,4. It is worth noting that there are a few abnormal sperm that appear with double heads, tailless, flat heads, and bent necks, especially in G2 of the experiment.
The percentage of dead spermatozoa showed a significant increase (p≤0.05) in G2 in comparison with G1, 3, and 4 groups, while non-significant between G1 and G3,4.
DNA integrity % of sperms showed a significant decrease (p ≤0.05) in G2 in comparison with G1, 3, and 4 groups, while non-significant differences were recorded between G1 and G3,4. Sperm with native double-stranded and normal DNA are represented by a green head, while sperm with denatured or single-stranded DNA are represented by a yellow to red head. Thus, AO reflects the sperm chromatin denaturation level.
Histopathological examination of testes showed no marked differences in terms of testicular architecture and germ cell layer maturation among the four groups.
It could be concluded that the chronic exposure of male albino rats to malathion resulted in biochemical and hormonal changes which were not associated with histopathological changes. However, when using Selenium nanoparticles at a high dose (4.0 mg/kg b.w.), it improves sperm parameters, hormonal and oxidative stress changes.
The results showed that selenium nanoparticles could be used as a prophylactic agent with precautions depending on dose. It is worth noting that further studies are required to confirm the idea of autophagia study.