tokens: In the present study , we found that fluvoxamine ( but not sertraline or paroxetine ) and the sigma - 1 receptor agonists ( SA4503 , PPBP , DHEA - sulfate ) could potentiate NGF - induced neurite outgrowth in PC12 cells , and that the effects of these drugs were blocked by co - incubation with the selective sigma - 1 receptor antagonist NE - 100 .