Nitric oxide causes apparent release of zinc from presynaptic boutons.
One of us showed previously [Cuajungco and Lees (1998) Brain Res. 799, 188-129] that nitric oxide injected into the cerebrum in 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 study, 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 microl) or control (spermine, 100 mM/2 l) was infused into the hippocampus or the cerebellar cortex. Two hours after infusion, N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) staining for zinc in the brains revealed that sperminenitric oxide, but not control (spermine only) produced up to 95% depletion of zinc staining from the zinc-containing boutons. TSQ-positive neurons were also conspicuous throughout injection sites, in both the cerebral cortex and in the cerebellar cortex, where 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.
Frederickson
C J
CJ
Center for Biomedical Engineering, and Department of Anatomy and Neuroscience, University of Texas Medical Branch, 625 Jennie Sealy Hospital, Galveston 77555, USA. chris@neurobiotex.com
Cuajungco
M P
MP
LaBuda
C J
CJ
Suh
S W
SW
D000818:Animals; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D019581:Neuropil / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015032:Zinc / Q000378:metabolism*
D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; D015032:Zinc