5-Hydroxytryptamine release in dorsal hippocampus of freely moving rats: modulation by pindolol.
1. The aim of the present study was to investigate the origin and modulation of 5-hydroxytryptamine release in dorsal hippocampus of freely moving rats using brain microdialysis. 2. Basal release of 5-hydroxytryptamine and 5-hydroxyindole-acetic acid was 3.0 +/- 0.2 pg/15 min and 519 +/- 18 pg/15 min, respectively. Stimulation by 60 mM K+ increased 5-hydroxytryptamine release by 66%. Inclusion of 10 microM tetrodotoxin in the perfusion medium reduced 5-hydroxytryptamine release to approximately 5% of basal levels. 3. In addition, release could be modulated by the 5-hydroxytryptamine receptor agonist 8-hydroxy-2-(di-N-propylamino)-tetralin (50 % decrease) and this effect was completely blocked by the 5-hydroxytryptamine-1 receptor antagonist pindolol. 4. These data are in concordance with results from the ventral hippocampus and indicate that release of 5-hydroxytryptamine is predominantly of neuronal origin. In contrast with other studies, the authors found the non-selective 5-hydroxytryptamine-1 antagonist, pindolol, to increase 5-hydroxytryptamine release by 65% following systemic administration. This may hint at a different autoreceptor control in serotonergic fibers ascending from the median raphe as compared to the dorsal raphe nucleus.
Bosker
F J
FJ
Department of Biological Psychiatry Academic Hospital Utrecht, The Netherlands.
Donker
M G
MG
Klompmakers
A A
AA
Kurata
K
K
Westenberg
H G
HG
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010869:Pindolol / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D011985:Receptors, Serotonin; D012701:Serotonin; D013779:Tetrodotoxin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D010869:Pindolol; D011188:Potassium