Progesterone is known to have anti-inflammatory action. This study looked at the anti-inflammatory action of progesterone on the myometrium of the uterus during pregnancy. The anti-inflammatory effect, in this study, was through Progesterone Receptor B. There was a change in the dominance to PR A late in pregnancy. This would promote inflammatory signaling and thus contractions with the onset of labor.
good discussion on progesterone receptors, coactivators, corepressors and their impact on breast cancer. The question is, do these findings have applications to non-disease.
study shows that mice lacking PR-A and PR-B (progesterone receptors) have increased uterine inflammation. Again, the inflammatory/pro-inflammatory effects of hormones may be regulated through receptors. This may be the reason that different stages of life elicit a different response with the same hormone.
Progesterone receptor (PR) shown to provide an important anti-inflammatory role in breast cancer in this study. PR shown to increase NF-kappaB inhibitor IkBalpha, shown to inhibit aromatase activity, shown to inhibit COX-2 expression and shown to inhibit HER-2/neu expression.
knowledge of progesterone and its metabolites are important in the use of hormones. As the authors concluded here: "natural steroids should not be disparaged...an update on endocrinological knowledge and experience is rather mandatory for gynecologists". There in lies the problem. The IOM has shown that the average physician practices at a level of 17 years behind the current scientific knowledge and the environment created by medical governing bodies discourages questions, so as to protect the system.