Effects of cortisol on tesicular apoptosis in goldfish (Carassius auratus)

Apoptosis is a programmed cell death that has been attributed to the action of stress hormones, such as cortisol. We investigated the in vitro effect of cortisol in goldfish (Carassius auratus) mature (GSI: ۲.۷۵-۴.۶۵) or immature (GSI: ۱.۹۴-۲.۴) testes. Testes were taken out and transferred into culture medium (M ۱۹۹), cut into ۲۰ mm thick slices and supplemented with fetal bovine serum (FBS), added different doses of cortisol (۰, ۵۰, ۱۰۰, ۲۰۰, ۴۰۰, ۷۵۰ and ۸۰۰ ng/ml) and incubated for ۲۴h, ۴۸h or ۷۲h at ۱۸°C. Samples were rinsed and homogenized with phosphate buffered saline (PBS) after incubation period. Duplicates or triplicates processed for caspase-۳ activity. The results showed a significant increase in caspase-۳ activity in immature testes after ۷۲h treatment with ۷۵۰ng/ml of cortisol (P<۰.۰۵), and also at ۴۰۰ng/ml (P<۰.۰۵). In contrast, no significant differences were observed between non-treated and cortisol-treated samples from mature goldfish testes. In this study we have demonstrated, for the first time that the stress hormone cortisol induces apoptosis in the goldfish testis in a stage-specific manner (immature testis).