Physiological changes of adipokines during the menstrual cycle
Background. The cyclical effects of hormones during the menstrual cycle (MC) are responsible for driving ovulation. The information about roles of adipokines within the scope of MC are not definite. Leptin plays a role in sexual function and regulating the onset of puberty. Thin girls often fail to ovulate or release an egg from an ovary during menstruation cycles. Leptin also acts on specific receptors in the hypothalamus to inhibit appetite. Levels of leptin are increased in women suffering from premenstrual syndrome. Aim. The aim of our study was to describe physiological changes of selected steroids and adipokines at healthy women during the MC. Methods. Twenty-seven women with regular menstrual cycles were included in the study. Each sample was collected in cooled EDTA tubes, centrifuged at 2000 rpm in a refrigerated centrifuge, and stored at -80 °C. For all samples we measured luteinizing hormone (LH), follicularstimulating hormone (FSH), sex hormone-binding globulin (SHBG), testosterone, dehydroepiandrosterone (DHEA), estradiol, 7α-DHEA, 7β-DHEA, 7-oxoDHEA, 17-hydroxyprogesterone (17-OH P), progesterone, cortisol, adrenocorticotropic hormone (ACTH) by RIA and IRMA. Levels in plasma of hormones associated with food intake (c-peptide, ghreline, GIP, GLP, GLP-1, glucagon, insulin, leptin, PAI-1, resistin and visfatin) were measured using magnetic bead-based multiple assays (x-MAP technology, Luminex Corporation). Two kits were used: the 10-plex Bio-Plex Pro Human Diabetes assay and the 2-plex Bio-Plex Pro Human Adiponectin and Adipsin assay (both Bio-Rad Laboratories). Patient. Twenty-seven women with regular menstrual cycles (cycle length 28±2 days) were included in the study. The average age of the women was 31.8±3.56, and average BMI 22.9±2.8. The women used no hormonal contraceptives or other medicines influencing the production of steroid hormones, and were non-smokers. Before enrollment in the study, all signed informed consent that was approved by the local ethical committee of the Institute of Endocrinology. Intervention. Fasting blood samples were taken in the morning between 7 and 8 am. The first sampling was done at the start of the menstrual cycle (1st or 2nd day). Subsequent samples were taken at regular intervals every three days, for a total of 10 samples taken during the study. Main outcome measures. During the MC we found increased levels of testosterone, estradiol, progesterone, and 17-hydroxyprogesterone during ovulation. SHBG gradually increased after ovulation. There was a significant decrease in resistin levels during ovulation, followed by an increase in the latter part of the cycle. Adipsin showed a notable increase during ovulation, but this increase was not statistically significant. Results. Classical changes in gonadotropins, estrogens and progesterone during the menstrual cycle are accompanied by less striking but significant changes in 17-hydroxyprogesterone and testosterone. No significant changes show dehydroepiandrosterone and its 7-oxygenated metabolites. Adipokines show a tendency to increase during ovulation, while ghrelin and resistin decrease. There is also a remarkable association of sex hormone binging globuline (SHBG) on the day of the cycle. Conclusions. Our results demonstrate that changes to adipokines during the menstrual cycle are not substantial. Differing leptin levels are characteristic for premenstrual syndrome. Precise descriptions of physiological changes in healthy women are important in helping us understand the significance of the changes accompanying various pathological states.