Modulation of Electrically Evoked Serotonin Release in Cultured Rat Raphe Neurons.
From: Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Laboratory of Neuropharmacology, Freiburg, Germany.
Journal of neurochemistry
- Publish Date: Mar 2007
- ISSN: 0022-3042
- Volume: 100
- Issue: 6
- Pages: 1613-25
- Medium: Print
- Language: English
- Citation (JAMA): Birthelmer Anja, Ehret Andreas, Riegert Céline, et al. Modulation of Electrically Evoked Serotonin Release in Cultured Rat Raphe Neurons.. J. Neurochem. Mar 2007;100:1613-25
Abstract
Electrically evoked release of serotonin (5-HT) and its modulation via 5-HT autoreceptors and alpha(2)-heteroreceptors was studied in primary cell cultures prepared from the embryonic (ED 15) rat mesencephalic brain region comprising the raphe nuclei. Cultures were grown for up to 3 weeks on circular glass coverslips. They developed a dense network of non-neuronal and neuronal cells, some of which were positive for tryptophan hydroxylase. To measure 5-HT release, the cultures were pre-incubated with [(3)H]5-HT (in the presence of the selective noradrenaline reuptake inhibitor oxaprotiline [1 micromol/L]), superfused with modified Krebs-Henseleit medium containing 6-nitroqipazine [1 micromol/L] and electrically stimulated using two conditions. Condition A: 360 pulses, 3 Hz, 0.5 ms, 90 mA, or condition B: 4 pulses 100 Hz, 0.5 ms, 90 mA (a condition which diminishes interactions with endogenously released transmitters during ongoing stimulation). After only 1 week in culture, the electrically evoked overflow of [(3)H] was Ca(2+) dependent and tetrodotoxin sensitive, suggesting an action-potential-induced exocytotic release of 5-HT. Using stimulation condition A in cultures grown for 2 weeks, both basal and evoked 5-HT release were strongly enhanced by methiotepine (1 micromol/L) but unaffected by the 5-HT(1B) autoreceptor agonist CP-93, 129 (1 micromol/L) and the alpha(2)-adrenoceptor agonist UK-14, 304 (1 micromol/L). Conversely, using stimulation condition B, not only CP-93, 129 (IC(50) 8.1 +/- 1.4 nmol/L) and UK-14, 304 (IC(50) 14.9 +/- 1.6 nmol/L) had inhibitory effects on cells grown for 2 weeks, but also the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)tetralin. In conclusion, we describe for the first time electrically evoked release of 5-HT from primary cultures of fetal raphe cells and its modulation via 5-HT(1B) and 5-HT(1A) auto- and alpha(2)-heteroreceptors. Such cultured raphe cells may represent a suitable model to study expression and development of presynaptic receptors on serotonergic neurons in-vitro.
Mesh Headings (Keywords): Animals, Calcium, Cells, Cultured, Chromatography, High Pressure Liquid, Electric Stimulation, Embryo, Mammalian, Female, Hydroxyindoleacetic Acid, Immunohistochemistry, Maprotiline, Nerve Tissue Proteins, Neurons, Pregnancy, Raphe Nuclei, Rats, Serotonin, Serotonin Uptake Inhibitors, Time Factors, Tritium, Tryptophan Hydroxylase
Check for Full Text / PubMed Unique Identifier (PMID): 17348865
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