Effect of acute lithium administration on pyroglutamyl-aminopeptidase I activity in several brain areas of the rat.

Lithium (CAS 7439-93-2) is widely accepted as an effective treatment in acute mania. A considerable body of literature exists on the effects of lithium on the central nervous system. However, the neurochemical mechanism of the ion action remains still relatively obscure. In the present work, the effect of acute lithium administration on pyroglutamyl-aminopeptidase I activity in discrete areas of the rat brain, including the hypothalamic-pituitary axis, is described. Increases of the enzyme activity in the striatum and the hypothalamus after lithium treatment were observed. It is suggested that this enzyme activity plays a part in the lithium action mechanism, possibly through the regulation of the activity of TRH (Thyrotropin Releasing Hormone) and/or histidyl-proline diketopiperazine.