Nitric oxide causes apparent release of zinc from presynaptic boutons

One of us showed preciously [Cuajungeo and Lees (1998) Brain Res. 799. 188-129] that nitric oxide injected into the cerebrum vivo causes zinc staining to appear in the somata of neurons and suggested that this staining of somata might be accompanied by a depletion (release) of zinc from axon terminals. In the present studs. we confirm earlier results and report that there is a dramatic loss (apparent release) of histologically reactive zinc from the boutons of zinc-containing axons induced by infusion of nitric oxide into the brain in vivo. Rats were anesthetized with halothane and a cannula was inserted into the hippocampus, Either nitric oxide donor (spermineNONOate, 100 mM/2 mul) or control (spermine. 100 mM/2 1) was infused into the hippocarripus or the cerebellar cortex. Two hours after infusion, methox 1-8-quinolyl)-para-toluenesulfonamide (TSQ) staining For zinc in the brains revealed that sperminenitric oxide, but not control (spermine only) produced tip to 95% depletion of zinc staining from the zinc-containing boutons. TSQ-positive e neurons were also conspicuous throughout injection sites, in both the cerebral cortex and in the cerebellar cortex,,A here the Purkinje neurons were especially vivid, despite the scarcity of zinc-containing axonal boutons. It is suggested that the TSQ-stainable zinc in somata might represent intracellular stores mobilized from within or permeating extracellular stores, (C) 2002 IBRO. Published by Elsevier Science Ltd, All rights reserved.