Distribution of voltage-dependent Na+ channels identified by high-affinity receptors for tetrodotoxin and saxitoxin in rat and human brains: quantitative autoradiographic analysis.
The localization of a putative voltage-dependent Na+ channel in adult rat and human brain was studied by light microscopic quantitative autoradiography using a tritiated derivative of tetrodotoxin ([3H]enTTX) and tritiated saxitoxin [( 3H]STX). Equilibrium binding experiments in the whole rat brain gave dissociation constants of 7.0 nM ([3H]enTTX) and 5.0 nM ([3H]STX). The dissociation constant for the binding of [3H]STX in the different human brain regions was near 1.5 nM. Autoradiograms demonstrated a heterogeneous distribution of toxin binding sites in the brain with a very good correlation of the mapping of tetrodotoxin and saxitoxin receptors. With the exception of a few regions, the same type of cartography was observed for human and rat brain structures. If toxin receptors were present in all brain regions, their density was particularly important in cerebral cortex, hippocampus, lateral septum and molecular layer of cerebellar cortex. Conversely, the medulla oblongata contained only low amounts of binding sites.
Mourre
C
C
Centre de Biochimie du C.N.R.S., Nice, France.
Moll
C
C
Lombet
A
A
Lazdunski
M
M
D000328:Adult; D029845:Amphibian Proteins; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D051381:Rats; D011919:Rats, Inbred Strains; D012530:Saxitoxin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels; D013045:Species Specificity; D013779:Tetrodotoxin / Q000378:metabolism*; D014316:Tritium
D029845:Amphibian Proteins; D002352:Carrier Proteins; D007473:Ion Channels; D015222:Sodium Channels; C027525:saxitoxin-binding protein, Rana catesbeiana; C023790:tetrodotoxin-binding protein; D014316:Tritium; D012530:Saxitoxin; D013779:Tetrodotoxin; D012964:Sodium