Abstract
Objective: Gibberellic acid (GA3) is a plant growth regulator (PGR), largely used in agriculture in many countries including Egypt. The purpose of this study was to investigate the effects of sub-chronic toxicity (8 weeks) of GA3 on testicular function and structure in adult albino rats, and to determine the effects of withholding of GA3 on the affected parameters for another 8 weeks of follow up period. Material and Methods: Forty adult male albino rats were equally divided into four groups; the first group was used as a negative control, the second group received 1ml of 1N NaOH (positive control group), the third group received 75 ppm of GA3 daily in drinking water for 8 weeks (GA3 group), and the last group received the same treatment as the third group for 8 weeks then was left without any treatment for another 8 weeks (recovery group). At the end of the experimental period, rats were sacrificed and the testes were examined by light and transmission electron microscope for detecting the histopathological changes, examination of sperm viability & count and measuring testicular malondialdhyde. Testicular sections were examined immunohistochemically for the detection of the anti-apoptotic Bcl-2 protein. Results: In GA3 treated group, histopathological changes were in the form of regression in spermatogenesis using light microscope, while electron microscopic examination revealed apoptotic changes in the Leydig cells and distortion of the adluminal compartment. These changes were accompanied by significant elevation in testicular malondialdehyde, while Bcl-2 showed week immunoreactions in the layers of spermatids. After the 8 weeks of GA3 withholding, significant improvement in the testicular function and structure with improvement of Bcl-2 immunoreaction. Conclusion: From the previous results, it can be concluded that GA3 exposure can induce reversible toxic changes in the testes of adult albino rats on sub-chronic exposures.
Highlights
Many chemicals are currently used in agriculture, and plant growth regulators (PGRs) are among those which are widely used
The lipid peroxidation end product malondialdehyde (MDA) significantly increased in the liver, lungs, heart and kidneys of rats treated with GA3 (Celik et al, 2007), where these findings indicated promotion of lipid peroxidation content and alteration in the antioxidant systems in the rat's various tissues treated with GA3
The obtained elevation in testicular MDA due to GA3 administration recorded in the present study can be explained by the study of Soliman et al (2010) who stated that PGRs are associated with the generation of reactive oxygen species which interact with tissues leading to numerous pathophysiological alterations
Summary
Many chemicals are currently used in agriculture, and plant growth regulators (PGRs) are among those which are widely used. The amounts of these substances placed into the environment may soon exceed those of insecticides (Celik and Tuluce, 2006). Gibberellins (a group belonging to PGR) are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf & fruit senescence (Fishel, 2006). They were discovered in 1926 by a Japanese scientist, Eiichi Kurosawa, who was studying bakanae, the “foolish seedling” disease in rice. It was first isolated in 1935 by Teijiro Yabuta from fungal strains of Gibberella fujikuroi (Drira, 2006)
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