NO NEURONAL REGULATION OF MURINE BONE-MARROW FUNCTION

Bone marrow is innervated by efferent (sympathetic) and afferent nerve s, but it is not clear whether these nerves affect cell formation or r elease in any significant way. To elucidate this problem, we studied m ice neonatally sympathectomized with 6-hydroxydopamine and adult mice in which one hind limb was surgically denervated. Progenitor and trans it cell numbers and proliferative activity were estimated in bone marr ow, blood, and spleen. In addition, we performed unilateral electrical stimulation of nerve fibers to tibial marrow and applied a cell mobil izing stimulus (bleeding, granulocyte colony-stimulating factor inject ion, or intraperitoneal injection of a chemotactic substance) to inves tigate cell egress from the marrow. Blood flow to hindleg bone marrow was assessed with the radioactive microsphere technique. Except for a smaller bone marrow cell population and lower body weight in neonatall y sympathectomized mice, we found no clear indications that bone marro w innervation influenced cell production. Also, the innervation did no t detectably affect cell release from the marrow. Electrical stimulati on of hind limb nerves did not change the blood flow to the marrow, wh ereas it markedly decreased blood flow to the overlying muscle. We the refore conclude that no obvious function can be ascribed to tibial mar row innervation in the mouse. (C) 1998 by The American Society of Hema tology.