Serum Levels of C Type Natriuretic Peptide in Different Reproductive Periods

Recent studies have shown that C natriuretic peptide (CNP) is produced from granulosa cells, increasing cumulative guanosine monophosphate (cGMP) production by affecting cumulus cells through natriuretic peptide receptors.It has been suggested that the transport of cGMP to oocyte via gap junctions causes a continuous increase in cyclic adenosine monophosphate (cAMP) levels within the oocyte. An important role of increased cAMP levels in oocyte is shown to suppress meiotic progression. Deoxyribonucleic acid (DNA) studies in animals have shown that expression of the natriuretic peptide precursor increases during the periovulatory period and shows that this increase decreases rapidly after Luteinizing hormone(LH) / human chorionic(hCG) stimulation. Human studies have shown that after ovulation induction, the CNP level in follicular fluid decreases following ovulatory dose of hCG (9).

In this prospective study, 60 patients are planned to recruite. Group 1 consists of 20 healthy reproductive aged women between 18-40 years old, with regular menstruation. Group 2 will include 20 patients in perimenopausal time period between 40-49 ages and in group 3 there will be20 postmenopausal women. Age, gravida, parity and body mass index (BMI) data of all patients will be recorded. BMI is calculated by dividing the body weight in kilograms by the square of the height in meters. All patients will go under ultrasound examination by the same clinician (ACO). The number of antral follicles in group 1 and group 2 will be recorded. In addition, on the 2nd or 3rd day of menstruation, serum FSH, LH and E2 data of the patients in group 1 and 2 will be recorded. For the last 6 months, patients with drug use that may affect menstruation like oral contraceptives, patients with cardiac or renal disease and therefore drug use, causes of infertility other than unexplained infertility, history of ovarian surgery, presence of polycystic ovary syndrome, and patients with irregular menstruation will be excluded for the study. In addition, patients with renal, cardiac, central nervous system and endocrine diseases will be excluded. Morning fasting venous blood samples will be taken from the patients on the 2nd or 3rd day of the menstruation for group 1 and 2. All blood samples will be centrifuged on the day of collection and separated serum samples and will be kept at -80 degrees until the day of CNP test. Serum CNP levels of the patients will be analyzed by an enzyme-linked immunosorbent (ELISA) assay for human CNP in accordance with the manufacturer's instructions (SEA721Hu, ELISA Kit for Human CNP, Wuhan USCN Business Co., Ltd., Cloud-Clone Corp., CCC, USA). Data will be analyzed using Statistical Package for Social Sciences software (SPSS v15, SPSS Inc, Chicago, IL, USA). The variables will be investigated using visual and analytical methods (histograms, homogeneity of variances test, Kolmogorov-Simirnov/Shapiro-Wilk's test) to determine whether or not they are normally distributed. Patient demographics and CNP values will be presented as median ± interquartile range. Gravida and parity will be demonstrated by frequency distribution. The correlation coefficients and their significance will be calculated using the Spearman test. P-values less than 0.05 will be regarded as statistically significant.