Love Hormone

             Over eighteen million people die each year from cardiovascular complications, such as coronary artery disease, which causes heart attacks.  Interruption of blood supply to the heart by blockage of coronary vessels deprives the cardiac tissue of oxygen and vital nutrients that can lead to cell death and loss of function, often with fatal consequences.  One of the great medical challenges has been to limit the extent of tissue damage during heart attacks and find a way to replace the dead cells with functional ones.  Due to the scarring that develops in these damaged cells (called cardiomyocytes), scientists have historically assumed they are not replaceable, though a smattering of evidence exists to suggest that these cells may still have some capacity to divide.                       

To address this issue, a research team at Michigan State University recently tested a battery of twenty important neuroendocrine hormones for their ability to stimulate heart epicardial stem cells to regenerate functional cells.  One of these hormones stood out: oxytocin.            

I’ve written before about oxytocin, a naturally occurring hormone produced in the hypothalamus region of the brain best known for controlling aspects of female reproduction such as contraction of the uterus during childbirth and milk release following lactation.  It is also involved in human behavior and has earned the name “love hormone” for its role in mother-infant bonding and romantic attachment.  Even positive social interaction between people and dogs (an action as simple as petting the dog) stimulates mutual release of this feel-good molecule.            

In the Michigan State study, both isolated human tissue and zebrafish were used to show how adult stem cells derived from heart epicardium (the outer layer of the heart) are reprogrammed by oxytocin into stem cells that can differentiate into a variety of cell types. These stem cells migrate into the deeper layers of the injured heart and repair damaged tissue by releasing healing factors and transforming into new cardiomyocytes (myo = muscle), blood vessels and fibroblasts (vital connective tissue cells).            

The head of the research team remarked that, “Oxytocin and several analogs are already employed in the clinic for other conditions, so it is easy to see it as a potential medication that could be administered to people right after myocardial infarction to boost endogenous regeneration, either as an injection in the bloodstream or maybe a pill using small molecule drugs.”          

 This is an exciting start, but it is still a long way from achieving similar effects in intact humans.  One of the challenges is the short half-life of oxytocin in the bloodstream.  However, it may be possible to create drugs with higher potency and longer half-lives.  Another issue is potential negative side effects of high dose oxytocin treatment.  Further, the understanding of what stimulating factors and chemicals are required for a long-term change needs to be maximized.            

Final thought: Since the most common role of oxytocin relates to bonding and pleasure, being in a caring and loving environment may promote heart healing.