Evidence that administration of an antioxidant with anticancer properties can prevent cyclophosphamide gonadotoxicity by modulating early ovarian response to oxidative stress

Study question: This work investigates whether oral administration of a natural carotenoid affects ovarian early response to cyclophosphamide (CPM) and prevents gonadotoxicity in female mice. Summary answer: Crocetin administration prior to CPM prevents gonadotoxic effect on ovarian reserve by modulating SIRT1 levels and mitochondrial damage. What is known already: Although oxidative stress (OS) is considered one of the mechanisms involved in CPM ovarian toxicity, the efficacy of in vivo antioxidant interventions has been poorly investigated. Dietary intake of some carotenoids, including saffron-derived crocetin, is known to exert potent anti-tumor effects and to protect non-malignant tissues against CPM toxicity throughout antioxidant and anti-inflammatory effects. An early sensor of OS is SIRT1, a deacetylase activated in response to changes in the redox state due to ROS increase and mitochondrial failure. By activating numerous targets SIRT1 orchestrates early response to OS and promotes cell survival or apoptosis. Study design, size, duration: Eighteen CD-1 female mice were divided in three groups and received a single intraperitoneal injection of 100 μl of PBS (CTRL), or an equal volume containing CPM (100 mg/kg) (CPM) or crocetin extracted from saffron (100 mg/kg) per os for 15 days prior to CPM administration (Crocetin+CPM). Participants/materials, setting, methods: Ovaries were analysed at 24 h post-CPM for SIRT1, SOD2, PGC1alpha, pAKT and pFOXO3a expression by Western blotting (WB). At 7 days post CPM ovaries were monitored for relative abundance of ovarian follicles by hematoxylin and eosin staining. Main results and the role of chance: Crocetin administration prior to CPMtreatment decreased follicles loss and inhibited PI3K/PTEN/AKT pathway involved in activation of follicle recruitment. Primordial and antral follicles were significantly increased in the crocetin+CPM group when compared with CPMmice (One-way ANOVA and Student–Newman–Keuls Multiple comparison p < 0.001). SIRT1 expression in CPM-mice was found to increase revealing the occurrence of OS. Mitochondrial superoxide dismutase SOD2 and the mitochondrial biogenesis activator PGC1alpha decreased suggesting that CPM-induced OS was associated with mitochondrial damage. Crocetin administration under conditions preventing follicle damage allowed the maintenance of basal levels of SIRT1 suggesting that preservation of redox balance can help the ovary counteracting ovarian damage by CPM. We also found that SOD2 and PGC1alpha were increased in crocetin + CPM mice providing evidence for mitochondrial protection. Limitations, reasons for caution: The main limitation of this study was the absence of direct quantification of SIRT1 enzymatic activity. Results can be translated to humans with caution. Wider implications of the findings: Our results aim to increase the knowledge of mechanisms underlying ovarian damage by CPM and will be helpful to develop new therapeutic opportunities for preserving fertility in cancer patients based on administration of antioxidants with anticancer properties. SIRT1 may be a biomolecular marker for evaluating cytotoxicity of other chemotherapeutic agents. Trial registration number: Not required.