To investigate whether the formation of vascular endothelial growth factor (VEGF) influences erythropoietin (EPO) expression in physiological conditions, we injected into the left lateral cerebral ventricle of the Mongolian gerbil an adeno-associated virus (AAV) vector capable of expressing the 165-amino-acid isoform of VEGF (VEGF165). Twelve and 18 days after AAV vector injection, the experimental animals were sacrificed and expression of EPO was evaluated through immunohistochemical analysis of both the hippocampus and the frontal cortex. We observed that VEGF165 induces EPO expression in the hippocampal pyramidal layers and in the frontal cortex of the gerbil, particularly after the 18th day following treatment with the vector, which suggests that VEGF165 could act as a hypoxic-like signal for EPO production. This finding could help to clarify the functional role of EPO and the molecular mechanisms by which VEGF might mediate its effects in the brain.
