Expression of cyclooxygenase-1 and -2 in the porcine endometrium during the oestrous cycle and early pregnancy.
Cyclooxygenase (COX) is the rate-limiting enzyme that catalyses the initial step in prostaglandins (PGs) production. In the present studies, endometrial COX-1 and COX-2 expression throughout the oestrous cycle and early pregnancy was analysed in pigs using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot and immunohistochemistry. There were no changes in messenger RNA (mRNA) and protein expression for COX-1 in cyclic pigs. In pregnant animals, mRNA levels of this enzyme increased on days 22-25 (p < 0.001). However, no upregulation of COX-1 protein was detected. Quantification of COX-2 mRNA expression during the oestrous cycle revealed significant increases on days 10-12 and 14 (p < 0.001 and p < 0.01 vs days 2-4, respectively). Protein levels were also increased on day 14 when compared with days 2-12 and 18-20 after oestrus. In pregnant animals, the patterns of both COX-2 mRNA and protein expression were similar. Messenger RNA levels were higher on days 16 and 22-25 (p < 0.01 vs day 10). Moreover, the protein content tended to increase on days 16 and 22-25. COX-1 and COX-2 were localized in the luminal and glandular epithelium as well as in the uterine stroma. In contrast to COX-1, a positive immunostaining reaction for COX-2 was detected only on days 12-16 after ovulation and on days 14-16 of pregnancy. In conclusion, these results indicate specific patterns of COX-1 and COX-2 expression in the porcine endometrium throughout the oestrous cycle and early pregnancy. COX-2 rather than COX-1 seems to be the primary enzyme responsible for modulated PGs production at the time of luteolysis in cyclic and during implantation in pregnant animals.
Blitek
A
A
Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Poland. agas@pan.olsztyn.pl
Waclawik
A
A
Kaczmarek
M M
MM
Stadejek
T
T
Pejsak
Z
Z
Ziecik
A J
AJ
D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D051545:Cyclooxygenase 1 / Q000235:genetics / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D004717:Endometrium / Q000201:enzymology*; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine
D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2