Sex Hormone Disruption and Histological Changes in Testes on Chronic Dichlorvos Exposure in Animal Model

Background: Dichlorvos is an organophosphate used indiscriminately as a pesticide in homes and for agricultural purposes. This study evaluated the effects of its low dose sub-lethal chronic exposure on male reproductive function using an animal (Rattus norvegicus) model.

Methodology: Three groups of rats were given dichlorvos at the dosages of 0.28 mg/kg, 0.56 mg/kg and 1.68 mg/kg respectively on alternate days. The control group was given only plain drinking water. The experiment lasted for 50 weeks.

Results: Dichlorvos induced a dosage variation effect on blood levels of follicle stimulating hormone but this was insignificant on levels of luteinizing hormone, oestrogen, progesterone and dihydrotestosterone. Prolonged treatment with dichlorvos had no overall influence on luteinizing hormone levels. The major histological findings in descending order of frequency included tubular atrophy and degeneration, germ cell depletion, germ cell exfoliation, tubular necrosis, spermatid retention and Leydig cell hyperplasia, each scored on a semi-quantitative scale. After 50 weeks of dichlorvos treatment, progesterone and oestrogen blood levels both had strong positive correlations with the frequency of germ cell exfoliation and residual bodies in the testes. In contrast, there was no statistically significant correlation between blood levels of follicle stimulating hormone, luteinizing hormone and dihydrotestosterone and the histological findings.

Conclusion: This research evaluated the chronic effect of low dichlorvos exposure on reproductive function using an animal model. There was a strong positive correlation between progesterone and germ cell exfoliation and residual bodies. Oestrogen also correlated with germ cell exfoliation, depletion and presence of residual bodies. Furthermore, the correlation between the blood hormone levels and histological changes in the testes was largely unpredictable.