Investigating the Effects of Hydro-alcoholic Urtica Dioica Extract and Retinoic Acid on Follicular Development: An Animal Study

Background: Urtica dioica (UD), as a natural antioxidant, has positive effects on oocyte maturation. This study aimed to investigate the effects of hydro-alcoholic UD extract and retinoic acid on follicular development in an in vitro fertilization (IVF) condition.    Methods: A total of 40 female Wistar rats were randomly divided into 5 groups: group 1 received normal saline, group 2 was given 25 mg/kg retinoic acid, group 3 was administered with 100 mg/kg UD extract, group 4 was treated with retinoic acid plus UD extract, and group 5 received 10 mg/kg olive oil. The histomorphometric parameters were analyzed, including the number of follicles, follicular atrophy, fertilized oocytes, 2-cell embryos, dead embryos, and blastocysts.    Results: Retinoic acid caused a significant increase in the primary, preantral, and atretic follicles and a substantial decrease in the corpus luteum compared with the control group (p<0.001). The number of preantral, antral follicles, and corpus luteum was significantly higher in group 3 compared with group 1 (p<0.001). Moreover, coadministration of UD plus retinoic acid (group 4) significantly reduced the atretic follicles (p<0.05).    Conclusion: Based on the results, UD herbal extract, as a natural antioxidant agent, could reduce the adverse effects of retinoic acid on oocyte maturation in an IVF condition.