Enhanced expression of P2X4 and P2X7 purinergic receptors in the myometrium of pregnant rats in preterm delivery models.

The expression levels of P2X purinergic receptors were determined in the myometrium of pregnant rats using the quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). The messenger RNAs (mRNAs) of P2X4 and P2X7 were expressed most strongly. The expression levels of these receptors increased during the late stages of pregnancy; at the time of delivery, the mRNA levels of P2X4 and P2X7 had increased to 1.9 and 3.2 times the day 19 values, respectively. We also explored the roles of P2X receptors in hormone-induced and inflammation-induced preterm delivery models. In the former, mifepristone caused the P2X4 and P2X7 mRNA levels to increase to 2.1 and 4.1 times the control values, respectively. In the latter, lipopolysaccharide (LPS) caused the mRNA levels of P2X4 and P2X7 to increase dramatically to 7.4 and 18.6 times the control values, respectively. These findings suggest that increased P2X4 and P2X7 receptor expression in pregnant rats is related to uterine contraction leading to term and preterm delivery.