Relationship Between Uterine Development, mRNA and Protein Expression of FSH and LH Receptors in New Zealand White Rabbits

Abstract

| Gonadotropin receptors; follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR), are well known for their indispensable function in female reproductive regulation. LHR and FSHR were previously thought to have only gonadal tissue expression, however it has recently been discovered that they are expressed in a range of extragonadal tissues. However, whether these receptors play a role in rabbit uterine development is uncertain. The objective of this study was to investigate the relationship between uterine development and mRNA and protein expression of FSHR and LHR in the New Zealand white rabbits. Uteri were collected from thirty New Zealand rabbits at Day 0, week (W) 2, W4, W16, and Day18 of pregnancy (n = 6/group), and ovarian histology, gene as well as protein expression were investigated using light microscopy, real-time PCR and Western blot, respectively. The findings revealed that uterus was not yet differentiated into its definite three layers, and there was no evidence of glandular development at birth. Primordium of uterine gland formation was first observed at W 2. By W16, extensive tubular glands underwent branching and coiling within the stroma. At pregnancy, endometrial glands became abundant. No significant changes in FSHR and LHR mRNA and protein expression were detected from birth to W16 which was not compatible with the linear increase of histological features of the rabbit uterus during developmental stages. However, the mRNA and protein for these receptors during pregnancy were significantly (p < 0.05) increased. In conclusion, there was no relation between rabbit uterine developmental changes and FSHR and LHR expression, suggesting that these receptors are not involved in regulating rabbit uterine development and that uterine development is controlled by other factors.