Finally, we further demonstrated that brain-derived neutrophic factor (BDNF), a trophic molecule recently found to induce PACAP expression in rat sensory and motor neurons after nerve injury [34] is likewise able to increase the expression of endogenous PACAP, PAC1 receptor and in turn of tPA in our cell system, likely acting as a booster of the endogenous PACAP/PAC1 signaling system. Here, BDNF is linked to injury.