Inhibition by nitric oxide of the uptake of [3H]serotonin into rat brain synaptosomes.
[3H]Serotonin (5-HT) uptake by synaptosomes of rat brain was dose-dependently inhibited by nitric oxide (NO) donors such as sodium nitroprusside (SNP), 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamin e, 3-morpholinosydnonimine and S-nitroso-L-cysteine (NO-CYS). The inhibitory effect was blocked by reduced hemoglobin. The effect was not mimicked by ferrocyanide and ferricyanide. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-bromo cGMP) did not affect [3H]5-HT uptake into rat cortical synaptosomes. The reduced activity of [3H]5-HT uptake into the cortical synaptosomes pretreated with NO-CYS was partially reversed by washing the preparation after the treatment. Kinetic analysis showed that NO-CYS (100 microM) decreased the Vmax value without any change in the Km value. NO-CYS did not affect the specific binding of [3H]paroxetine, a ligand that binds to the 5-HT transporter, in membranes. NO-CYS and SNP, like iodoacetic acid and sodium cyanide, decreased the ATP content in cortical synaptosomes, but the effect on ATP content was not related to that on [3H]5-HT uptake. These findings suggest that NO inhibits reversibly [3H]5-HT uptake into rat brain synaptosomes without affecting the recognition site of the 5-HT transporter in a cGMP-independent manner, and the observed effect is not due to its metabolic effect.
Asano
S
S
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Japan.
Matsuda
T
T
Nakasu
Y
Y
Maeda
S
S
Nogi
H
H
Baba
A
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009569:Nitric Oxide / Q000494:pharmacology*; D017374:Paroxetine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism
D002352:Carrier Proteins; D006454:Hemoglobins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D012701:Serotonin; D017374:Paroxetine; D000255:Adenosine Triphosphate; D006152:Cyclic GMP