I have no direct answer to Debbi's question: < Is there such a thing as
lack of oxytocin receptors?>
Rather than go too far over my head in responding to this question, I
will reply with some observations and further questions.
You say this mother received pitocin, which for induction is diluted in
intravenous fluid so as to be able to regulate the amount of uterine
response with more precision.
It's administration, in IV solution, is often continued for at least a
short while after delivery to guard against hemorrhage. (I am not even
taking into account here the IV fluids administered solely to avoid
hypotension from an epidural.)
I hope someone more knowledgeable has some explanation or references
regarding the chemical similarity of antidiuretic hormone (ADH) and
competition for binding sites.
Perhaps the answer to your question lies not in any lack of oxytocin
receptors/binding sites, but in competition with ADH for those sites.
Though they are both secreted from the same lobe of the pituitary and
have some chemical similarities, the main purpose of ADH is in helping
regulate the salt and fluid balance of the body, so that every cell in
the body has the optimum range of sodium for cell function. Oxytocin
itself has some slight tendency to effect homeostasis in the same way as
ADH.
Therefore mothers who have had pitocin induction have at least two
factors that affect the breast and seem to make engorgement more severe:
1) the competition with ADH for binding sites, and interference with
natural balance of diuresis. 2) overhydration due to more fluid on board
than nature intends.
These mothers seem to experience more prolonged swelling all over their
bodies. It is especially noticeable in their lower extremities, their
brains, as well as their breasts. This swelling does not seem to
resolve/diurese completely until 2 weeks or so after birth. (Many HCP's
caring almost exclusively for mothers whose labor is managed this way,
probably consider this as the norm, since they see it so often.)
Also, though pitocin is artficially manufactured, it is supposed to be
chemically the same as natural oxytocin except for the part that could
elevate blood pressure. Can we be certain whether it has the same effect
on binding sites as natural oxytocin, especially when the arbitrary
amount administered may cause a distorted feedback to the pituitary
affecting the amount of ADH secreted? IME, there seems to be a direct
correlation between the severity of engorgement with the length of the IV
pitocin induction.
Is its entrance directly into the blood stream causing the same effect on
the brain that oxytocin being secreted via the pituitary does?
This is an important part of the history that the LC needs to know: what
labor interventions/anesthetics did the mother receive? Mothers who
deliver at home, or at birthing centers usually do not receive IV's and
probably not much, if any, pitocin. I would like to hear some midwives
who care for mothers with both kinds of births about any contrast in the
amount of edema present in the breasts in the first 7-14 days.
Did I answer your question? No. Did my additional questions stimulate
anyone else to comment? I hope so.
Jean
********
K. Jean Cotterman RNC, IBCLC
Dayton, Ohio, USA
(whose 6 kids surprised her last week with an advance birthday present
for her big 70 in the fall - a BRAND NEW COMPUTER WITH ALL THE BELLS AND
WHISTLES! (Now all I have to do is learn to use it better!)
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