Acid, basic and neutral soluble and membrane-bound aminopeptidase activities after lidocaine administration in discrete areas of the rat brain.

It has been suggested that aminopeptidase activity could play an important role in the regulation and biotransformation of several neuroactive peptides. Lidocaine is a local anesthetic widely used in therapeutics and as antiarrhythmic agent. However, information concerning possible alterations in the neuropeptide metabolism after treatment with this anesthetic is lacking. This being the case, in the present paper we have studied the activities of three aminopeptidases (Asp-, Leu- and Lys-aminopeptidase) in several brain areas after lidocaine administration. The study includes the activities of the soluble and membrane-bound forms. Soluble neutral and basic aminopeptidase activities show significant decreases after lidocaine administration in the frontal cortex. Soluble Lys-aminopeptidase also shows a significant decrease in the pituitary gland. On the other hand, membrane-bound Leu-aminopeptidase activity shows significant decreases not only in the frontal, but also in the parietal cortex and in the thalamus. These data might suggest that the neuropeptide transmission and/or modulation could be activated by lidocaine.