The effect of Thymol on testicular toxicity caused by subchronical cadmium exposure in the rats

Objective: The aim of this study was to investigate the testicular damage that may occur with subchronical exposure to cadmium, the importance of antioxidant/oxidant balance in this damage and the possible effects of thymol, which has antioxidant properties, against this damage histologically and biochemically. Methods: In our study, 40 male Sprague-Dawley rats aged 6-7 weeks were divided into 4 groups. In our subchronic study, the experimental period was determined as 90 days. During the experimental period, the control group was exposed to 0.08% ethanol, the cadmium group to 50 mg/L cadmium chloride, the thymol group to 111.1 mg/L thymol and 0.08% ethanol, and the cadmium+thymol group to 50 mg/L cadmium chloride, 111 mg/L thymol and 0.08% ethanol containing drinking water ad libitum. The rats were weighed weekly during the experimental period. On day 91, the rats were sacrificed by decapitation under ketamine anaesthesia. The left and right testes were used for histological and biochemical analyses, respectively. The left epididymis was used for sperm analysis, while the right epididymis was used for histological analysis. In histological analysis, haematoxylin & eosin staining was performed on epididymis tissues and haematoxylin & eosin, Masson trichrome, periodic acid-Schiff and TUNEL staining were performed on testicular tissues. In biochemical analysis, testosterone, caspase-3, tumour necrosis factor-alpha, total oxidant status, total antioxidant status, oxidative stress index, glutathione peroxidase levels were determined. Results: According to the data obtained; cadmium decreased body and testicular weight, decreased percentage of sperm vitality, increase in teratozoospermic index relative increase in tail anomalies in the distribution of anomalies, decreased Johnsen's score, increased percentage of lumen with immature cell shedding, increased percentage of tubules with reduced spermatozoa in the lumen and detached epithelium, decreased total seminiferous tubule volume, decreased total seminiferous tubule length and area, It was observed that germinal epithelium thickness to seminiferous tubule diameter ratio and seminiferous epithelium area to seminiferous tubule area ratio decreased, total Sertoli cell count and total round spermatid count decreased, Leydig cell count per interstitial area and round spermatid count per gram testis decreased, daily sperm production and daily sperm production per gram testis decreased, connective tissue area percentage increased. Among these damage parameters caused by cadmium, thymol provided statistically significant improvement only in body mass, sperm vitality percentage and Johnsen score. It caused partial improvement in the percentage of lumen with immature cell shedding, tubules with reduced spermatozoa in the lumen and tubules with epithelial separation, total seminiferous tubule volume, ratio of germinal epithelial thickness to seminiferous tubule diameter and seminiferous epithelial area to seminiferous tubule area, and percentage of connective tissue area. Conclusions: As a result, cadmium decreased body and testicular weight, sperm vitality, Johnsen score, tubular tissue volume, tubule length, tubule area, ratio of germinal epithelial thickness to seminiferous tubule diameter, ratio of epithelial area to seminiferous tubule area, percentage of various testicular cells and connective tissue; teratozoospermic index, percentage of lumen with immature cell shedding, percentage of tubules with reduced spermatozoa in the lumen, percentage of tubules with detached epithelium, while thymol caused significant improvement only in body weight, percentage of sperm vitality and Johnsen score.