5-Hydroxytryptamine sub(2B) receptors stimulate Ca super(2+) increases in cultured astrocytes from three different brain regions

• Published in: Neurochemistry international Vol. 36; no. 4-5; pp. 427 - 434
• Main Authors: Sanden, N, Thorlin, T, Blomstrand, F, Persson, PAI, Hansson, E
• Format: Journal Article
• Language: English
• Published: 01-04-2000
• ISSN: 0197-0186

The expression of 5-hydroxytryptamine-2B (5-HT sub(2B)) receptor mRNA has recently been shown in cultured astrocytes. Here the expression of functional 5-HT sub(2B) 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 ([Ca super(2+)] sub(i)). The 5-HT sub(2B) agonist alpha -methyl 5-HT (40 nM) produced rapid transient increases in [Ca super(2+)] sub(i) in astrocytes from all three brain regions studied, and these responses were blocked by the selective 5-HT sub(2B) antagonist rauwolscine (1 mu M). 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 mu M), a specific 5-HT sub(2A)/5-HT sub(2C) antagonist, to block these responses. The 5-HT sub(2B)-induced increases in [Ca super(2+)] sub(i) persisted in Ca super(2+)-free buffer, indicating that the increase in [Ca super(2+)] sub(i) results from mobilization of intracellular Ca super(2+) stores. The expression of 5-HT sub(2B) receptors on astroglial cells was further verified immunohistochemically and by Western blot analysis. These results provide evidence of the existence of 5-HT sub(2B) receptors on astrocytes in primary culture.