Results
Involvement of Ca2+ on the mechanism of acute Roundup-induced testis toxicity
Initially, rat testes were exposed to glyphosate–Roundup at concentrations ranging from 0.72 to 360 ppm, corresponding to 0.00072 to 0.36 g/L, respectively, and 45Ca2+ uptake was investigated. It is important to emphasize that Roundup is used in agricultural work at dilutions ranging from 10,000 to 20,000 ppm (10 to 20 g/L), concentrations much higher than those described in our results. Results showed that Roundup exposure for 30 min increased the 45Ca2+ uptake at doses ranging from 7.2 to 36 ppm glyphosate; however, 360 ppm Roundup lead to an important decrease in 45Ca2+ influx (Fig. 1A). To investigate whether the alterations in 45Ca2+ uptake were related to cell death, LDH release from the rat testis was measured. Interestingly, we observed an apparent link between 45Ca2+ uptake and LDH release at 36 ppm (0.036 g/L) Roundup (Fig. 1B). Otherwise, at the higher Roundup dose (360 ppm), the LDH release was higher, despite the decreased 45Ca2+ uptake (Fig. 1B). These findings strongly suggest that necrotic cell death could be directly related to Ca2+ toxicity up to 36 ppm of the pesticide. However, at very high concentrations (360 ppm), more complex mechanisms leading to necrotic cell death in the rat testis seem to be elicited by this xenobiotic. Therefore, in this study, we were interested in investigating some mechanisms underlying Ca2+ toxicity in rat testis exposed to 36 ppm Roundup.