Anti-B-50 (GAP-43) antibodies decrease exocytosis of glutamate in permeated synaptosomes.
The involvement of the protein kinase C substrate, B-50 (GAP-43), in the release of glutamate from small clear-cored vesicles in streptolysin-O-permeated synaptosomes was studied by using anti-B-50 antibodies. Glutamate release was induced from endogenous as well as 3H-labelled pools in a [Ca(2+)]-dependent manner. This Ca(2+)-induced release was partially ATP dependent and blocked by the light-chain fragment of tetanus toxin, demonstrating its vesicular nature. Comparison of the effects of anti-B-50 antibodies on glutamate and noradrenaline release from permeated synaptosomes revealed two major differences. Firstly, Ca(2+)-induced glutamate release was decreased only partially by anti-B-50 antibodies, whereas Ca(2+)-induced noradrenaline release was inhibited almost completely. Secondly, anti-B-50 antibodies significantly reduced basal glutamate release, but did not affect basal noradrenaline release. In view of the differences in exocytotic mechanisms of small clear-cored vesicles and large dense-cored vesicles, these data indicate that B-50 is important in the regulation of exocytosis of both types of neurotransmitters, probably at stages of vesicle recycling and/or vesicle recruitment, rather than in the Ca(2+)-induced fusion step.
Hens
J J
JJ
Department of Medical Pharmacology, Rudolf Magnus Institute for Neurosciences, Utrecht University, The Netherlands.
Ghijsen
W E
WE
Weller
U
U
Spierenburg
H A
HA
Boomsma
F
F
Oestreicher
A B
AB
Lopes da Silva
F H
FH
De Graan
P N
PN
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005089:Exocytosis; D019922:GAP-43 Protein / Q000276:immunology / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D013301:Streptolysins / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D019922:GAP-43 Protein; D013301:Streptolysins; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D002118:Calcium; D009638:Norepinephrine