Expression of calbindin D9k and vitamin D receptor in the uterus of Egyptian buffalo during follicular and luteal phases.
Uteri of mature Egyptian buffalo cows (5 10 years old) were collected at follicular (n=12) and luteal (n=16) phases of estrous cycle to investigate the expression of calbindin D9k (CaPB 9k) and vitamin D receptor (VDR) This study was done using avidin biotin immunohistochemistry method. In addition, blood levels of calcium (Ca) vitamin D3 (Vit D) estrogen (E2) and progesterone (P4) were measured. The immunohistochemical findings restricted the expressions of CaBP 9k and VDR to the luminal and glandular epithelia of the endometrium implicating the importance of CaBP 9K and VDR in the function of endometrial epithelium, especially the glandular one, in order to prepare a receptive uterus. On the other hand, the myometrium did not express CaBP 9k or VDR that denies the potential role of CaBP 9k and VDR in the uterine contractility during the estrous cycle of Egyptian buffalo. All of Ca, Vit D, and P4 blood levels significantly (P<0.05) increased during luteal phase however, blood level of E2 significantly (P<0.05) increased during follicular phase. The expressions of CaBP 9k and VDR in the uterus of Egyptian buffalo were significantly (P<0.05) higher during luteal (P4 dominant) phase than during the follicular (E2 dominant) phase indicating that P4 up regulates the expressions of CaBP 9k and VDR. In view of these observations, this study represents the first characterization of CaBP 9K and VDR expression in the uterus of Egyptian buffalo and suggests the pivotal role of CaBP 9k and VDR in the uterine receptivity. Furthermore, it demonstrates the regulatory role of P4 for expressions of CaBP 9k and VDR in buffalo uterus.
Acta histochemica