Re: Stimulus for the release of erythropoietin

There is a connection between the brain and the production of erythropoietin
the way there is, essentially, a connection between the brain and just about everything 
your body does.  Actual secretion of the hormone is from the kidney, but it 
is in response to lowered blood levels of oxygen - due to hemorrhage, or impeded
blood flow or blood pressure (especially if it occurs in the renal circulatory system somewhere).
Erythropoietin (EPO) secretion can also be stimulated by an overall reduction 
in number of red blood cells (or a reduction in their oxygen-carrying capacity), 
or simply by moving to a high altitude.  These, however, aren't the only things that 
will stimulate release of EPO, that release can also be secondary to release of something
like growth hormone (GH) - which is secreted from the pituitary, which is in the brain.
Obviously, as an organism grows larger, so does the circulatory capacity, hence the effect of
GH on EPO.  However these and any other stimuli for release of EPO will only be
secondary.  Certain androgens can also have a secondary effect on EPO, as can thyroxine, 
a metabolic hormone produce by the thyroid gland.  And of course, without the
essential components necessary for construction of red blood cells, erythropoeisis
cannot occur; that is, you need iron and vitamins - things you can only get from the 
stomach.

Human physiology is all tightly interconnected - it would be VERY difficult to 
dissect out one tiny little part of it that would NOT have a tremendous, and probably
lethal, effect on everything else.  So is the brain involved?  Yes, it would have to be,
if only in an apparently secondary way.

I have taught human A&P for years.  When I discuss EPO, I typically only mention
decreased oxygen levels (and their possible causes) in the blood.

Good question!