Effects of gestational age and labor on expression of prostanoid receptor genes in baboon uterus

We determined the effect of gestational age and labor on the regional expre ssion of prostanoid receptor genes in baboon myometrium. Cesarean hysterect omy was performed on 15 pregnant baboons of known gestational age in the la st third of pregnancy, five of them during spontaneous term labor Expressio n of prostanoid receptor genes was studied using Northern blot analysis. Tr anscripts of similar size to the human were detected for prostanoid EP1, EP 2, EP3, EP4, IP FP, and TP receptor genes using Northern blot analysis. The re were no gestational age-related changes in expression of these genes. Ex pression of EP1, EP3, and IP receptor RNA mRNA was significantly higher in myometrium from the fundus (compared with the lower segment), whereas EP2 g ene expression was significantly lower in the fundus. Labor was associated with a reduction in the regional variation of both EP1 and IP receptor gene expression, but not EP1 and EP3 expression. Labor was also associated with an overall lower level of expression of EP2 receptor mRNA. We conclude tha t regional and labor-related variation in myometrial expression of prostano id receptor genes may have a key role in primate parturition.