Figure 1.

The effects of progesterone (P4) on uterine contraction and oxytocin sensitivity. (A) After a stable response was obtained, spontaneous contractions were measured. Uterine contractions were recorded with a force transducer, and the power was determined by calculating the AUC (area under the contraction curve) at the final 5 min. (B) The mean AUC of spontaneous contractile activity was decreased by 37% in the Porphyromonas gingivalis (P.g.) + P4 group (n = 6) compared to the P.g. group (n = 8) at day 18.0 of gestation. (C) Mean AUC values for uterine contractions induced by various oxytocin concentrations. Oxytocin was added to the tissue organ bath at 20 min intervals in increasing concentrations from 1 pM to 300 nM. Experiments were performed in duplicate using 6–8 independent tissue samples. Statistical analysis was performed using the Mann–Whitney U test. Statistical significance was set at *: p < 0.05. Values represent mean  ±  SD (n  = 6–8).