Immunohistochemical Detection of Receptors for Oestrogen and Progesterone in Endometrial Glands and Stroma during the Oestrous Cycle in Nelore (Bos taurus indicus) Cows

Abstract

The aim of the present study was to monitor endometrial distribution and concentrations of oestrogen receptors alpha (ER alpha) and progesterone receptors (PR) by immunohistochemistry in Nelore cows (Bos taurus indicus) during the oestrous cycle. Blood samples were collected for progesterone measurement and endometrial samples were taken from the uterine horn contra lateral to the corpus luteum in 16 cows at days 0 (ovulation), 5, 9, 13 and 19 of the oestrous cycle. Immunostaining evaluation for ER alpha and PR in the glandular epithelium and uterine stroma was performed by two methods: positive nuclei counting and staining intensity of the nuclei. Specific positive staining reactions for both receptors were limited to cell nuclei and they were not identified in the cytoplasm. The proportion of ER alpha positive nuclei had a temporal variation throughout the oestrous cycle in both cell types evaluated and was higher in uterine stroma than the glandular epithelium (p < 0.05). The greatest proportion of ER alpha stained nuclei was observed at oestrus and during the initial and mid luteal phase (days 5, 9 and 13) (p < 0.05) in the glandular epithelium and at days 0, 5 and 9 in the uterine stroma (p < 0.01). The proportion of PR positive nuclei remained constant throughout the entire oestrous cycle for both cell types evaluated (p > 0.05). A higher proportion of PR positive nuclei was measured in the uterine stroma compared with the glandular epithelium (p < 0.05). Intensity of staining for ER alpha and PR varied throughout the oestrous cycle (p < 0.01). There was a higher staining intensity at days 0 and 5 in the stroma for ER alpha (p < 0.01) and PR (p < 0.01) and in the glandular epithelium at days 0, 5, 9 and 13 for ER alpha (p < 0.01) and at days 0, 5 and 9 for PR (p < 0.01) when compared with the other evaluated days. These data demonstrate that ER alpha and PR expression varied throughout the oestrous cycle in Nelore cows, in general with highest concentrations at oestrus and the lowest during the luteal phase. This is similar to patterns observed in Bos taurus taurus.

Detecção imunoistoquímica de receptores de estrógeno e progesterona no endométrio de vacas Nelore (Bos taurus indicus) durante o anestro pós-parto

“…Por ser uma técnica semiquantitativa, a presença e a intensidade da marcação refletem, respectivamente, a positividade da célula e a concentração destes receptores (Martin et al, 2008). Neste estudo, optou-se pela realização de duas avaliações: contagem de núcleos positivos e negativos e escore representativo da porcentagem de núcleos fortemente marcados.…”

“…Esse mesmo comportamento foi observado em animais Bos taurus indicus da raça Nelore (Martin et al, 2008).…”

“…Os receptores endometriais de progesterona (RP) apresentaram a mesma dinâmica de modificação ao longo do ciclo estral observada para os RE (Boos et al, 1996, Robinson et al, 2001, Martin et al, 2008.…”

Effect of endometrial biopsy on uterine health in tropically adapted beef cattle

“…According to Figueiredo et al (1997), P4 concentration increased steadily from the second day post-ovulation and reached a plateau at approximately Days 8 to 16, remaining elevated until luteolysis, which occurred between Days 16 and 19 of the oestrous cycle (Sartori and Barros, 2011). Martin et al (2008) characterised the circulating P4 during the normal oestrous cycle in Nellore heifers. P4 increased from low concentrations at Day 0 (0.09 ± 0.13 ng/ml) and went up to concentrations above 1 ng/ml during early dioestrus at Day 5 (1.92 ± 1.17 ng/ml), reaching the maximum plateau from Day 9 (3.20 ± 1.46 ng/ml) to Day 13 (3.30 ± 1.41 ng/ml).…”

Efeito do tratamento com progesterona e do diâmetro folicular nas características histológicas e moleculares uterinas em vacas Nelore em anestro pós-parto

“…Em bovinos, a expressão dos ER uterinos apresenta alterações temporais e espaciais ao longo do ciclo estral porém, de maneira geral e simplista, a expressão dos ER uterinos é diretamente proporcional às concentrações circulantes de E2 e inversamente proporcional às concentrações circulantes de P4, estando portanto, mais expressos durante o proestro e estro do que durante a fase luteal (BOOS et al, 1996;ROBINSON et al, 2001;MARTIN et al, 2008 …”