Effect of lithium treatments on the tyrosine-aminopeptidase activities in the rat brain and the pituitary gland.

J M de Gandarias, J Irazusta Astiazaran, A Varona, D Fernández, J Gil, L Casis

Index: Arzneimittelforschung 49 , 816-819, (1999)

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Abstract

Lithium (CAS 7439-93-2) is being utilized widely for the treatment of manic-depressive illness. However, the neurochemical mechanism of the ion action still remains relatively obscure. In the present work, the effect of acute lithium administration on soluble and membrane-bound enkephalin-degrading tyrosine-aminopeptidase activities in discrete brain areas and the pituitary gland is described. Tyrosine-aminopeptidase activities have been measured fluorometrically using Tyr-beta-naphthylamide as substrate and puromycin as selective inhibitor of one of the two membrane activities. Soluble and membrane-bound puromycin-insensitive Tyr-aminopeptidase activities are greater in the pituitary gland after treatment with 5 and 10 meq/kg of lithium. It is suggested that these enzyme activities could play a part in the lithium action mechanism.