Determination of estrous period in female rats (Rattus norvegicus) by fourier transform infrared (FTIR) spectroscopy through identification of reproductive hormone in blood samples

Some methods in fertility study have been developed until now. One of the methods is determining estrous cycle by analyzing the concentration of reproductive hormones. Generally, hormone analysis method is destructive, difficult and expensive. Condition of fertility was analyzed by determining the concentration of progesterone using FTIR spectroscopy in this research. Blood samples were taken from ten rats during three estrous and non-estrous phases. The proportion of vaginal epithelium cells were qualitatively observed by vaginal smear to get the cycle phases determined. Blood samples were analyzed by FTIR, scanned in 400-4000 cm ^-1. RIA was used as a comparison method to analyze the samples. FTIR spectra were used to determined progesterone concentration in blood. Absorbance values of functional groups which represented progesterone such as ketone (1724 cm ^-1), methyl (1375 cm ^-1) and methyl-ketone (1354 cm ^-1) were compared to hemoglobin's (1425 cm ^-1) absorbance value which has relatively constant value during the cycles. RIA has confirmed progesterone concentration during the cycles. Estrous condition was achieved at level 17,593 ± 4,246 ng/ml blood (FTIR relative absorbance to hemoglobin = 0,853 ± 0,310). Non-estrous condition was achieved at level 76.218 ± 4.687 ng/ml blood (FTIR relative absorbance to hemoglobin = 1,024 ± 0.268).