[Reproductive and developmental toxicity studies of paclitaxel. (I)--Intravenous administration to rats prior to and in the early stages of pregnancy]

Effect of intraperitoneal docetaxel on ovarian function in mice

Taxanes are important chemotherapeutic agents used to manage breast cancer and gynaecological malignancies. However, ovarian toxicity induced by the taxane docetaxel (DOC) is of great concern. We investigated DOC-induced toxicity in the ovaries of female CD1 strain mice. The mice were divided into control (saline), DOC-5 (5 mg/kg DOC), and DOC-10 (10 mg/kg DOC) groups and administered saline or DOC on the first day of the study and two weeks later. Two weeks after the second dose, the ovaries were removed for analysis after inducing superovulation. Ovary weight, the number of secondary follicles, and the total number of follicles were reduced after DOC administration. Additionally, the expression levels of caspase-3 and the pro-apoptotic protein Bcl-2 interacting mediator of cell death (BIM) increased. Our findings suggest that high-dose DOC induces damage to growing follicles; however, it may not affect primordial follicles.Impact statementWhat is already known on this subject? Docetaxel (DOC) is one of the most effective chemotherapeutic agents used to manage various cancers. Some in-vitro studies have examined paclitaxel-induced ovarian toxicity; however, limited research on DOC is available.What do the results of this study add? We investigated DOC-induced ovarian toxicity in female CD1 strain mice at 5 mg/kg and 10 mg/kg. We found that DOC reduced ovary weight, the number of secondary follicles, and the total number of follicles, with the higher dose having a higher effect.What are the implications of these findings for clinical practice and/or further research? We believe that our study makes a significant contribution to the knowledge about the effect of DOC on ovarian function.

Transient impact of paclitaxel on mouse fertility and protective effect of gonadotropin‑releasing hormone agonist

Paclitaxel (PXL) is a chemotherapeutic agent widely used in solid tumors. However, whether PXL causes premature ovarian insufficiency in women of reproductive age remains controversial. The aim of the present study was to answer how and for how long PXL affects fertility, and to identify the protective effect of gonadotropin-releasing hormone agonist (GnRHa) in mice. A single dose of PXL was administered to 7-week-old female ICR mice. Mice were treated with GnRHa for 1 estrous cycle prior to chemotherapy, and for another following chemotherapy. On the days 1, 6, 11 and 16 following the administration of PXL, mice were assessed by ovarian histology, ovarian stimulation and mating experiment. Multiple doses of PXL were also administered to verify the duration of the gonadotoxicity of PXL. It was determined that PXL only destroyed antral follicles on day 1 following chemotherapy without reducing primordial follicles. In vitro experiments revealed that PXL impaired oocytes in metaphase, excluding those at the germinal vesicle stage. The number and quality of retrieved metaphaseII(MII) oocytes in PXL-exposed mice were reduced on day 1 following chemotherapy, which was recovered on day 11. MII oocytes from mice pretreated with GnRHa recovered on day 6 following chemotherapy. Following 3 estrous cycles in mice after the last dose of the 3-dose paclitaxel administration, follicles in all stages and retrieved MII oocytes were recovered. It was concluded that the impairment caused by PXL on follicles and oocytes in mice lasted for <3 estrous cycles, which was shortened by pretreatment of GnRHa.

What lies behind chemotherapy-induced ovarian toxicity?

Seminal advances in anticancer therapy as well as supportive care strategies have led to improved survival rates, posing an emphasis on preserving an optimum quality of life after cancer treatment. This recognition has paved the way to an increasing research of long-term side effects, both clinical and preclinical and to an ongoing design of a supportive care system to evaluate and treat long-term adverse effects of anticancer treatments, including the impact on fertility. As with many adverse effects induced by anticancer treatments, the literature comprised mostly clinical data with regard to chemotherapy-induced gonadotoxicity, while understanding of the biological mechanism is lagging. The impact of anticancer treatments on female fertility depends on the women's age at the time of treatment, the chemotherapy protocol, the duration, and total cumulative dose administered. Several suggested mechanisms that underlie chemotherapy-induced gonadotoxicity have been described. This review illustrates the clinical evidence, as well as its supportive preclinical studies, while proceeding from the 'bedside to the bench work' and provides an insight to what lies behind chemotherapy-induced gonadotoxicity.

The rat spermatogenesis after injection of paclitaxel (antitumor agent)

Morphological and functional characteristics of spermatogenesis in rats were studied during the early and delayed periods after single injection of paclitaxel (antitumor agent) in the maximum tolerated dose. The drug induced structural changes in the gonads associated with oligospermia and increased number of pathological forms of spermatozoa with reduced functional activity.

Effect of chemotherapy on primordial follicular reserve of rat: an animal model of premature ovarian failure and infertility

AIM

To determine the effect of paclitaxel and cisplatin in the reduction of primordial follicular reserve in rat.

MATERIAL AND METHODS

Thirty young female rats were divided randomly into three groups of 10 rats each. Paclitaxel 7.5 mg/kg and cisplatin 5 mg/kg were administered intraperitoneally in a single dose sterile technique to paclitaxel (n=10), and cisplatin (n=10) groups, and sterile saline solution was given to a control group (n=10). To assess the effects of chemotherapeutic agents on the primordial follicles, the rats were oophorectomised 7 days after the administration of chemotherapeutic agents. Haematoxylin and eosin staining was used to determine the number of primordial follicles. Primordial follicles were identified by the presence of an oocyte encapsulated partially or completely by a single layer of flattened follicular cells without a theca layer at the ovarian cortex.

RESULTS

The number of primordial follicles in the control group was 23.1 +/- 16.1 follicles. The number of primordial follicles were decreased significantly in both paclitaxel and cisplatin groups compared to control group (10.3 +/- 13.0 and 13.9 +/- 15.2 follicles, respectively) (P=0.001 and P=0.01, respectively). The difference in the number of primordial follicles between the paclitaxel and cisplatin groups was insignificant (P=0.465).

CONCLUSION

The administration of high dose paclitaxel and cisplatin to young rats causes the depletion of primordial follicles. However, no significant difference was observed between the two agents.