Red blood cells
Researchers say they have uncovered a new function of arginine vasopressin (AVP).
It seems this hormone does more than maintain fluid balance for the kidneys.
AVP also stimulates the proliferation and differentiation of red blood cell precursors and improves recovery from anemia, according to the researchers.
The group speculates that drugs targeting an AVP receptor could be used to replenish red blood cells lost due to bleeding or treatment toxicity.
Eva Mezey, MD, PhD, of the National Institutes of Health in Bethesda, Maryland, and her colleagues conducted this research and reported the results in Science Translational Medicine.
The team uncovered the unexpected role for AVP by examining clinical data from 92 patients with central diabetes insipidus, a condition that causes AVP deficiency.
Of those individuals, 87% of males and 51% of females had anemia. In comparison, anemia rates in the US general population range from 1.5% to 6% for men and 4.4% to 12% for women.
The researchers also found that all 3 AVP receptors are present on human and murine hematopoietic stem and progenitor cells.
One of these receptors, AVPR1B, plays a predominant role in red blood cell production.
Further experiments revealed that AVP-deficient rats had delayed recovery from anemia, but treatment with AVP or the AVPR1B agonist d(Leu4Lys8)VP was able to speed up anemia recovery in mice.
The researchers tested AVP and the AVPR1B agonist in mouse models of hemorrhage. Compared to vehicle-treated mice, AVP-treated mice had an increase in hematocrit and reticulocyte numbers by day 2. Mice that received d(Leu4Lys8)VP only had an increase in reticulocytes.
The team also tested mice exposed to sublethal irradiation. When the mice received AVP for 2 days, they saw increases in hematocrit and corrected reticulocyte numbers.
The researchers then tested splenectomized mice subjected to hemorrhage. AVP-treated mice had an increase in hematocrit that was similar to that observed in non-splenectomized mice.
Finally, the researchers found that AVP’s effect on hematocrit is independent of erythropoietin. The team said AVP “appears to jump-start peripheral blood cell replenishment,” but later, erythropoietin seems to take over.
