>>I simply don't understand the concept with receptor sites that you are
describing with the word "upregulated".
I believe it was Kate Halberg who also said something about receptor sites
"shifting from oxytocin to prl"?
I don't have too much of a base in organic chemistry, but can someone
amplify/simplify some of this for me? Any references I can read?<<
Jean,
I won't pretend to be an expert in this, but I'll do my best to explain what
I've been working to learn and understand.
First, all hormones have receptors, which are usually located in "target
organs;" you could say that they work like locks and keys, the receptors
being the locks and the hormones being the keys. These two parts arise from
mechanisms that may be independent, or may be partially interrelated. The
latter seems to be the case with oxytocin.
We know, for instance, that pregnancy helps develop oxytocin receptors in
the uterus, but that there is a large proliferation of them in the 24-48 hrs
prior to labor--some factor causes an upregulation of the oxytocin receptors
at this time. (This may be why induced labors don't "take" in some women)
"Regulation" refers to a controlling mechanism that either causes or
suppresses proliferation; "upregulate" causes them to proliferate, while
"downregulate" decreases their numbers.
To complicate things, there are hormones that are very close in structure--
oxytocin and ADH, or prolactin & human growth hormone. It seems that in some
instances you can have one hormone but not the other, and still get a
response from the target organ. Do they share the same receptors, or do they
fool each other's receptors in some cases? I don't think we fully understand
all of these nuances.
In regards to regulation of receptors, there are some intriguing
relationships to consider. Testosterone is supposed to downregulate
prolactin and estrogen receptors; oxytocin is supposed to upregulate
oxytocin and estrogen receptors. I am sure that there are many more
interrelationships, but I also have not uncovered them yet. I've asked Dr.
Craig more than once where I can read more on this, but he really couldn't
direct me to any particular reference, referring instead to lesser known
research. I wish there was something that just told me how every hormone can
impact every other hormone's receptor! If someone finds it, please let me
know. In the meantime, I continue to glean info wherever I can.
A note on prolactin...... ever seen a woman whose prolactin levels are
normal for her lactational phase yet she isn't making much milk? I've been
wondering if it is a problem with receptors, which in the case of prolactin
could affect pregnancy breast development and/or milk production.
There is so much to learn!
Lisa Marasco, IBCLC
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