The role that the tridecapeptide neurotensin (NT) plays in the modulation of the aminoacidergic transmission is analyzed in different rat brain regions. NT exerts its effects through the activation of different receptor subtypes, NTR1, NTR2 and NTR3. The contribution of NTR1 receptor in modulating and reinforcing glutamate signalling will be shown including the involvement of interactions between NT and N-methyl-D-aspartate (NMDA) receptors. Extracellular accumulation of glutamate and the excessive activation of glutamate receptors, in particular NMDA receptors, is known to represent an important factor in the induction of glutamate-mediated neuronal damage occurring in Parkinson's disease and in pathologic events such as hypoxia and ischemia. An enhancing action of NT on glutamate-induced neurodegenerative effects is shown and NTR1 receptor antagonists could therefore become novel pharmaceutics in the treatment of neurodegenerative disease.