Bee venom induced in vivo ultrastructural reactions of cells involved in the bone marrow erythropoiesis and of circulating red blood cells.

Ultrastructural answer of bone marrow erythroid series and of red blood cells (RBCs) in Wistar rats to bee venom (BV) was analyzed by transmission and scanning electron microscopy, and corroborated with hematological data. A 5-day and a 30-day treatment with daily doses of 700 μg BV/kg and an acute-lethal treatment with a single dose of 62 mg BV/kg were performed. The 5-day treatment resulted in a reduced cellularity of the bone marrow, with necrosed proerythroblasts, polymorphous erythroblasts, and reticulocytes with cytoplasmic extensions, and a lower number of larger RBCs, with poikilocytosis (acanthocytosis) and anisocytosis, and reduced concentrations of hemoglobin. After the 30-day treatment, the bone marrow architecture was restored, but polymorphous erythroblasts and reticulocytes with thin extensions could still be observed, while the RBCs in higher number were smaller, many with abnormal shapes, especially acanthocytes. The acute treatment produced a partial depopulation of the bone marrow and ultrastructural changes of erythroblasts including abnormal mitochondrial cristae. The RBCs in lower number were bigger and crenated, with reduced concentrations of hemoglobin. Overall, BV was able to promote stress erythropoiesis in a time- and dose-related manner, mitochondrial cristae modification being a critical factor involved in the toxicity of the BV high doses.