5-Hydroxytryptamine2B receptors stimulate Ca2+ increases in cultured astrocytes from three different brain regions.
The expression of 5-hydroxytryptamine-2B (5-HT2B) receptor mRNA has recently been shown in cultured astrocytes. Here the expression of functional 5-HT2B receptors has been studied in cultured astrocytes from rat cerebral cortex, hippocampus, and brain stem. Fluo-3- and fura-2-based microspectrofluorometry was used for measuring changes in intracellular free calcium concentrations ([Ca2+]i). The 5-HT2B agonist alpha-methyl 5-HT (40 nM) produced rapid transient increases in [Ca2+]i in astrocytes from all three brain regions studied, and these responses were blocked by the selective 5-HT2B antagonist rauwolscine (1 microM). The specificity of the responses to alpha-methyl 5-HT was further demonstrated by the failure of 4-(4-fluorobenzoyl)-1-(4-phenylbutyl)-piperidine oxalate (1 microM), a specific 5-HT2A/5-HT2C antagonist, to block these responses. The 5-HT2B-induced increases in [Ca2+]i persisted in Ca2+-free buffer, indicating that the increase in [Ca2+]i results from mobilization of intracellular Ca2+ stores. The expression of 5-HT2B receptors on astroglial cells was further verified immunohistochemically and by Western blot analysis. These results provide evidence of the existence of 5-HT2B receptors on astrocytes in primary culture.
Sandén
N
N
Institute of Neurobiology and Institute of Clinical Neuroscience, Göteborg University, Sweden.
Thorlin
T
T
Blomstrand
F
F
Persson
P A
PA
Hansson
E
E
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D005110:Extracellular Space / Q000378:metabolism; D007150:Immunohistochemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D044403:Receptor, Serotonin, 5-HT2B; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D044403:Receptor, Serotonin, 5-HT2B; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; C042390:alpha-methylserotonin; D012701:Serotonin; D002118:Calcium