Folic acid and beta-carotene decrease sister chromatid exchange (SCE) rate in patients undergoing controlled ovarian hyperstimulation (COH)

Abstract

One of the commonly used methods to determine the DNA damages of mammalian cells is SCE. We1 had previously reported an association between DNA damage in infertile women’s lymphocytes with exogenous gonadotropins. Thus the aim of this study is to evaluate DNA repairing effect of antioxidant agents (Folate and beta-carotene) in patients undergoing COH. Prospective case-control study. A total of 20 women undergoing IVF/ICSI with standard luteal long GnRH-a suppression (leuprolide acetate) and step-down protocols (recombinant FSH) were included in the study. The inclusion criteria were the absence of any malignancy, no history of chemotherapy or radiotherapy or no smoking. All patients underwent ICSI cycle and maximum 3 embryos were transferred on day 3. Three heparinized peripheral blood samples from these patients were obtained at different time intervals referring as the baseline (prior to COH) (Time I), at the day of human chorionic gonadotropin injection (Time II) and 12 days after ET (Time III). Peripheral blood lymphocytes from each sample taken above mentioned time intervals were cultured in three different tubes. For each patient, folic acid (2.27×10-7 M) (Group 1) and beta-carotene (1×10-6 M) (Group 2) were added to tube 1 and tube 2 respectively after 24 hours of the culture, and 3rd tube added noting referred as control tube (Group 3). Chromosome harvesting was performed to each tube for a single patient after addition of colcemide at 68th hour. Differential staining of chromatids at the time of metaphase plaque was done with Hoechst-Giemsa treatment and SCE values for each sample were analyzed. The presence of disturbed color continuity and color changes between the opposite paired chromatids were assessed as a break. The scoring unit for SCE was the average of the chromatid changes per metaphase plaques after 200 metaphase plaques were counted. Values were expressed as mean ± SD. Mann-Whitney U and Wilcoxon-Sign rank tests were used to analyze data. Type 1 error was set at 0.05. Mean age±S.D. of the patients was 29.7±5.9. Mean duration of gonadotropin stimulation was 9.1±1.1 days and mean total dose of gonadotropins used was 1597.9±247.1 IU and mean estradiol level on the day of hCG administration was 1251.1±773.2 pg/ml. Although all tree groups had comparable mean number of SCE at the baseline, a statistically significant increment of SCE score was noted in control group when compared to group I and group II at both time I and II. All values of the SCE were given in Table 1. Increased DNA damage may indicate the increased potential for malignancies after superovulation. However, supplementation of patients with folic acid or beta-carotene may decrease this potential toxic effect. 1 Baltaci V, Zeyneloglu HB. Increased frequency of sister-chromatid exchange and altered alkaline comet assay scores in superovulation cycles for unexplained infertility. Eur J Obstet Gynecol Reprod Biol 2004;113:73.