Adverse testicular effects of Botox® in mature rats

Botox® injections are taking a consistently increasing place in urology. Intracremasteric injections, particularly, have been applied for cryptorchidism and painful testicular spasms. Studies outlining their safety for this use are, however, scanty. Thus, the present study aimed at evaluating possible testicular toxicity of Botox® injections and their effect on male fertility. Mature rats were given intracremasteric Botox® injections (10, 20 and 40 U/kg) three times in a two-week interval. Changes in body and testes weights were examined and gonadosomatic index compared to control group. Semen quality, sperm parameters, fructose, protein, cholesterol and triglycerides contents were assessed. Effects on normal testicular function were investigated by measuring testosterone levels and changes in enzyme activities (lactate dehydrogenase-X and acid phosphatase). To draw a complete picture, changes in oxidative and inflammatory states were examined, in addition to the extent of connective tissue deposition between seminiferous tubules. In an attempt to have more accurate information about possible spermatotoxic effects of Botox®, flowcytometric analysis and histopathological examination were carried out. Botox®-injected rats showed altered testicular physiology and function. Seminiferous tubules were separated by dense fibers, especially with the highest dose. Flowcytometric analysis showed a decrease in mature sperms and histopathology confirmed the findings. The oxidative state was, however, comparable to control group. This study is the first to show that intracremasteric injections of Botox® induce adverse testicular effects evidenced by inhibited spermatogenesis and initiation of histopathological changes. In conclusion, decreased fertility may be a serious problem Botox® injections could cause.