The comparison of reproductive hormone receptor expressions of the sheep ovary and hormone concentrations in two Chinese breeds

Abstract

The aim of this research was to investigate the changes in reproductive hormone receptor expressions of the ovary and hormone concentrations between oestrous cycle pattern of two different sheep breeds in China. Ovarian tissues were collected from Chinese Merino (Junken type) and Hu sheep with different reproductive states in spring and autumn. Serum samples were assayed for oestrogen (E2), progesterone (P), luteinizing hormone (LH) and follicle‐stimulating hormone (FSH) concentrations by radioimmunoassay during spring. The ovarian expression of hormone receptors (ERα, ERβ, PR, LHR and FSHR) was analysed using real‐time reverse transcription polymerase chain reaction (RT‐PCR). In Chinese Merino, there was no corpora lutea and ovulation point on the surfaces of ovaries in spring and low basal levels of both LH and P in serum. ERα, ERβ and FSHR were expressed significantly higher in Merino ovaries during anoestrus compared with oestrous or luteal phases of Hu sheep (p < 0.05 or p < 0.01). However, both varieties of sheep exhibited a similar tendency to secrete E2 and FSH. Compared with Hu sheep, FSH levels were slightly higher in Merino serum. In Hu sheep, ERα, ERβ, FSHR, LHR and PR expressed in luteal phase ovaries during spring were significantly lower (p < 0.05, p < 0.01 or p < 0.001) than autumn. Interestingly, LHR and PR expressed in anoestrous ovaries were similar to that in oestrous phase of both sheep breeds. The above results suggest that seasonal reproductive sheep increased the expression of E2 and FSH receptors in ovary during spring may enhance the effects of E2 and FSH on follicular development. It is likely that this enhancement prevents the ovary from progressing to the luteal phase.

Regulation of uterine function during estrous cycle, anestrus phase and pregnancy by steroids in red deer (Cervus elaphus L.)

“…Our results have clearly shown that LH concentration in hinds’ plasma was at a similar level during all analyzed seasons, but we did not analyze the preovulatory outflow period. Nevertheless, our results differ from the results obtained by Li et al 9 . In anestrus sheep, the concentration of LH in the serum was lower than during the reproductive season.…”

“…In the uterus and ovary, progesterone (P4) plays key physiological roles under the control of the pituitary hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH) 9 and it affects the release of mature oocytes, supports implantation, maintains of pregnancy, and inhibits contractions of the myometrium 10 . During pregnancy, this steroid is synthesized by the corpus luteum, however, in the further stages of pregnancy, the placenta produces it in most mammal species, such as cow 11 , pig 12 , roe deer 13 , and human 14 .…”

Regulation of Uterine Function During Estrous Cycle, Anestrus Phase and Pregnancy by Steroids in Red Deer (Cervus elaphus L.)

“…Our results have clearly shown that LH concentration in hinds' plasma was at a similar level during all analyzed seasons, but we did not analyze the preovulatory out ow period. Nevertheless, our results differ from the results obtained by Li et al [9]. In anestrus sheep, the concentration of LH in the serum was lower than during the reproductive season.…”

“…Low levels of P4 during anestrus in goats and high levels of P4 in the luteal phase in sheep, during the middle of reproductive season, were observed by Thimonier [38]. In turn, Li et al [9] did not observe a luteal P4 peak in sheep during anestrus.…”

Regulation of Uterine Function During Estrous Cycle, Anestrus Phase and Pregnancy By Steroids in Red Deer (Cervus Elaphus L.)

“…Low levels of P4 during anestrus in goats and high levels of P4 in the luteal phase in sheep, during the middle of reproductive season, were observed by Thimonier 38 . In turn, Li et al 9 did not observe a luteal P4 peak in sheep during anestrus. In comparison, our results showed a signi cant increase in P4 concentrations during the 13th day of the estrous cycle, while in the anestrus phase, this hormone's level was the lowest.…”