Effects of chrysin on testicular damage induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during prepubertal period

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) that persists in the environment for a long time is a prototype of dioxin family that contains 75 distinct compounds having similar biological effects on organisms and causing toxicity with same structural mechanism. TCDD has been employed as a standard in toxicity assays due to its characteristic of being the most toxic one among those compounds. TCDD existing also in exhaust and cigarette smoke is an environmental pollutant which is a by-product of insecticide production and solid waste combustion of municipalities. People generally take TCDD through nutrition and it tends to accumulate in blood and adipose tissues due to its low degradability. International Cancer Research Foundation has described TCDD as group I carcinogenic. TCDD causes inflammation by increasing arachidonic acid from membrane phospholipids and oxidative stress and also cell damage by producing reactive oxygen species (ROS). Being a naturally occurring flavone, chrysin (CH) has antioxidant, antiinflammatory, anti-apoptotic and anti-viral effects. It is also known that chrysin has vascular protective and spasmolytic effects. The present study was designed to investigate the effects of CH on possible oxidative testicular damage induced by TCDD. In this experimental study, 4-week-old 28 Wistar-Albino male rats about 105-130 g weight were used. The rats were grouped into four random groups, i.e. Group I (Control), Group II (TCDD-treated), Group III (TCDD+CH-treated) and Group IV (only CH-treated). Group II and III were treated with 25 μg/kg TCDD once a week intraperitoneally (ip.). In addition, Group III and IV were treated daily with 50 mg/kg CH dissolved in olive oil through gavage feeding. After 5 weeks, all rats were weighed and decapitated under anaesthesia. Testicle tissues were weighed immediately and fixated in Bouin's solution. For biochemical examinations, blood samples were centrifuged and the serums were stored at -20Ԩ for subsequent testosterone assay. Paraffin blocks from testicle tissues were prepared for histological examination. 5 μm-thick cross-sections of paraffin blocks were prepared and stained by using histochemical and TUNEL techniques. When compared with the control group, the groups of TCDD and TCDD+CH showed statistically significant decrease in the percentage of body weight variation and relative testicle weight. The difference between the groups CH and control was found to be insignificant statistically. During the microscope examination, Spermatogenic cells forming seminiferous tubule germinal epithelium and Sertoli cells, interstitial region and Leydig cells were found to have normal appearance in testicular tissues of the control group while atrophy in germinal epithelium, vacuolar degeneration, separation among germ cells, giant spermatid cells and arrest in certain stages of meiosis in some tubules were distinguished in tissues of TCDD-treated group. Relative protective effect was observed in testicular tissues of the CH-treated group against TCDD toxicity. Testicular cross-sections of only CH-treated group was observed normally as in control group. Apoptotic cell death was examined by TUNEL staining and the labelling results were observed as TUNEL (+) for control group, TUNEL (+++) for TCDD group, TUNEL (+) for TCDD+CH and TUNEL (+) for CH group. When compared to the control and CH groups, a significant decrease in serum testosterone levels of the rats treated with TCDD or TCDD+CH was observed. The difference between the control and CH group was found to be insignificant statistically. In conclusion, it was determined that TCDD toxicity decreased serum testosterone level and had a negative impact on spermatogenesis. Moreover, it caused serious cell damage that contain atrophy in seminiferous tubule germinal epithelium and apoptotic cell death. Prominent with its antioxidant effect, CH relatively reduced these negative impacts. These findings suggest that TCDD, an environmental pollutant, can affect male reproductive health individually and there is necessity for taking precautions against this threat.