Expression of Cyclooxygenase-1 and Cyclooxygenase-2 in Rabbit Endometrium during Early Pregnancy and in Early Stage Embryos

Cyclooxygenase is a rate limiting enzyme that converts arachidonic acid to prostaglandin.It exists as two isoforms:cyclooxygenase 1(Cox 1) and cyclooxygenase 2(Cox 2),which are encoded by separate genes.RT PCR method is used to study the expression of Cox 1 and Cox 2 in rabbit endometrium during early pregnancy by semi quantitative method and to study their expression in early stage embryos by qualitative method.Cox 1 is constitutively expressed in the endometrium during early pregnancy and it can be detected in every stage of early embryos.There is obvious change for Cox 2 expression in the endometrium.A high level of Cox 2 expression is detected on day 1 of pregnancy,it decreases from day 2 to 5,increases again from day 6,and reaches its highest level on day 8.Cox 2 can only be detected in expand blastocyst and hatched blastocyst.The stage specific expression of Cox 2 may be related to embryo hatching and implantation.