LAUSR

Significance Vascular endothelial growth factor (VEGF) plays a critical role in motoneurons. Low levels of VEGF lead to motoneuron degeneration in mutant mice, which can be alleviated by VEGF delivery. We have recently shown that axotomy-induced alterations in abducens motoneurons recover completely after VEGF administration. Therefore, we tested, in vivo, whether retrograde VEGF blockade could affect the physiology of intact, uninjured abducens motoneurons. By means of extracellular single-unit recordings and immunocytochemistry, we have found that VEGF blocking produces a marked reduction in motoneuronal firing and eye-movement–related sensitivities, as well as a profound synaptic stripping. Altogether, our findings point to VEGF as an essential retrograde neurotrophic factor for extraocular motoneurons.