Cytogenetic evaluation of patients in relation to the use of oral contraception

Assessment of DNA damage in women using oral contraceptives

The effect of the use of an oral contraceptive (OC) on the frequency of sister chromatid exchanges (SCEs) and on the response in the alkaline comet assay (single-cell gel electrophoresis (SCGE)) was investigated in 18 women taking contraceptive pills daily for 24 months. As controls, fertile women were included with regular menstrual cycles who received no OC drugs. A significant increase in the number of lymphocytes with DNA migration and an increased frequency of SCE per metaphase were observed in OC users as compared with their age-matched untreated controls (P<0.005). As higher incidences of spontaneous SCEs in peripheral blood lymphocytes have been reported to occur in females during pregnancy due to profound changes in the levels of certain sex hormones such as progesterone and estrogen, particularly during the last trimester, 17 pregnant women served as positive controls in this study in order to test the rate of genetic damage due to those changes. Higher frequencies of SCEs and comet responses were observed in pregnant women than in their matched controls. However, no statistically significant difference in DNA damage was observed between OC users and pregnant women (P>0.05). This study underscores the fact that prolonged and extensive use of these drugs in our daily life may be hazardous and also, that OC users should be aware of multifactorial risk factors (environmental, genetic and life style patterns) that may be responsible for additional DNA damage.

Sister-chromatid exchange frequencies in postmenopausal hormone replacement patients

Our objective was to evaluate the frequency of sister-chromatid exchange (SCE) during hormone replacement therapy in postmenopausal women. Thirty-four asymptomatic postmenopausal women with a minimum 12 months since last menstrual period and surgical menopausal women were included in the study. Seventeen patients who were in spontaneous menopause were administered conjugated estrogen and medroxyprogesterone acetate (group A), and the others who were in surgical menopause were given 17beta-estradiol only (group B). Peripheral lymphocytes were obtained at the beginning and at the end of the third month of therapy. The mean age of the patients was 50. 67+/-4.79. There were statistically significant differences in terms of SCE frequencies between pre- and posttreatment levels of both groups (p<0.001 and p=0.003, respectively). It is likely that estrogens with or without progesterone have an effect in increased SCE frequency and this issue may be an evidence for the increased potential for malignancies.

Genotoxic effect of Anovlar 21, an oral contraceptive, on mouse bone marrow

Anovlar 21, a combination drug containing the oestrogen ethinyloestradiol and the progestin norethisterone acetate, was studied for its in vivo genotoxic effect on the bone marrow cells of Swiss albino mice. The chromosomal aberration assay and the micronucleus test were employed for the study. 0.08, 0.4, 0.8, 1.6, 3.2, 4.8, 6.4 and 8.0 mg/kg/day of the drug was orally administered for 15 consecutive days to mice. Bone marrow preparations were made 24 h after the final feeding. The lowest dose, 0.08 mg/kg, represents the human therapeutic range. Marrow preparations of mice fed 0.8 mg/kg/day for 15 days were made at 6, 12, 24, 48 and 96 h, and 1, 2 and 3 weeks and a time-yield analysis was carried out. Statistically significant increases in chromosomal aberrations were observed in animal groups fed doses of greater than or equal to 0.4 mg/kg/day. In the time-response study, the maximum frequency of aberrations was noted at 24 h, thereafter decreasing gradually with increasing time. But the drug did not induce a significant increase in the number of micronuclei in bone marrow erythrocytes at any of the doses or time intervals studied.

Steroid hormones enhanced sister-chromatid exchange in cultured CHO cells

The influence of steroid hormones on the induction of sister-chromatid exchange (SCE) in cultured CHO cells was studied. It was observed that estradiol-17 beta, estriol, estrone and ethynyl estradiol treatments enhanced SCE rates compared to the controls. Overall, these compounds produced a dose response effect. The importance of a detailed study on the long-term genetic effects of steroids on mammalian cells is emphasized.

Possible effects of hormonal contraceptives on human mitotic chromosomes

Chromosome breakage, as an indicator of genetic damage, was assessed in peripheral blood lymphocytes of 44 women using different types of hormonal contraceptives (HC) for various periods of time, as well as on 44 matched controls. The selection of individuals for this study was preceded by the completion of a questionnaire to avoid, as far as possible, all cases subjected to known clastogenic agents. 48-h cultures were established by standard techniques and every sample from each "study" individual and her own matched "control" were simultaneously and similarly processed. The use of HC was found to be associated with a highly significant increase of chromosome aberrations in this in vivo study (p less than 0.001). The likelihood that the association found is a causal one is suggested and the theoretical clinical implications of these findings are discussed.

Inducibility of chromosome aberrations by steroid hormones in cultured Chinese hamster ovary cells

The effect of steroid hormones on the chromosomes of cultured Chinese hamster ovary (CHO) cells was studied. It was noticed that estradiol-17 beta, estrone, estriol and ethynyl estradiol were effective in producing various types of chromosome aberrations. The percentage of these abnormalities increased with increasing concentrations of steroids used. The importance of detailed and long-term investigations on the influence of these compounds on mammalian chromosomes is discussed.

Further investigations on the cytological effects of some contraceptives

Anovlar induces a mitodepressive effect, producing abnormal prophases and a considerable number of micronuclei, i.e. Anovlar can produce major cytological abnormalities. On the other hand, Lyndiol induces minor abnormalities leaving the process of mitosis to proceed almost normally. Microgynon 30 did not show any effect on any of the mitotic stages. Our conclusion may offer an explanation for the contradictory results found in the literature upon the cytological effect of oral contraceptives, although the major chemical constitution of all contraceptives used is the same, still there are minor differences in their chemical structure. These minor differences in chemical structure may be the deciding cause whether or not a contraceptive is harmful.

The chromosomal effects of the oral contraceptive

A general review of reports on the chromosomal effects of oral contraceptive has been undertaken, and it is quite apparent that there is a scarcity of literature on these very important investigations. Also, those that have been undertaken, cannot be properly assessed on account of, one supposes, subjects' background and lack of numbers, differences in techniques and, above all, the small number of metaphases analyzed. Apart from the report by Mills and colleagues [16], none of the reports mentioned exogenous agents to which the subjects might have been exposed, especially in cases where there has been an increased frequency of chromosomal aberrations. All these considerations must be taken into account for, as yet, the reports are too conflicting to 'indict' the oral contraceptive as having chromosome-breaking properties.