Hormone Replacement Therapy Good?

Recent research proposes that estrogen is neither good or bad in terms of physiological effects. In the past, estrogen produced favorable effects on plasma lipid profiles, increased fibrinolysis, and acted as a vasodilator to lower systemic blood pressure and increase organ blood flow. An important action of estrogen is to stimulate NO synthse (NOS) activity. It is the disposition of nitric oxide(either coupled or uncoupled) that will then determine which product predominates and therefore , whether the overall effect of estrogen will be beneficial or harmful. As a woman ages there is a decline in factors critical for maintaining NOS in the 'coupled' state. Uncoupled oxidation generates Oc rather than NO. O2 has been suggested to play a role in age-related increased corocary vascular resitance and mediates the contractile response of estrogen on vessels.

Researchers used consisted of in vitro cell cultures, western blot analysis, and flourescence studies. The experiments indicate that estrogen can either relax or contract the arterial system depending on whether NOS activity is coupled or uncoupled to NO production, with either NO orO2, respectively, exerting the predominate influence. Yet, in aging women, NOS activity is ucoupled, resulting in a contractile response to the estrogen.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16162867&dopt=Citation