TAC1 and Parkinson disease: Even though the pleiotropic (and homeostatic) effects of the neuropeptides imply that their action have to be analyzed carefully in each specific pathological condition (see, e.g., the neuroprotective effect of a substance P antagonist in a Parkinson's model [187]), it can be suggested that the neuropeptides are well suited to act as inhibitors of microglia activation in different brain disease models in vivo.