N. Sanden et al., 5-Hydroxytryptamine(2B) receptors stimulate Ca2+ increases in cultured astrocytes from three different brain regions, NEUROCHEM I, 36(4-5), 2000, pp. 427-434
The expression of 5-hydroxytryptamine-2B (5-HT2B) receptor mRNA has recentl
y been shown in cultured astrocytes. Here the expression of Functional 5-HT
2B receptors has been studied in cultured astrocytes from rat cerebral cort
ex, hippocampus, and brain stem. Fluo-3- and fura-2-based microspectrofluor
ometry was used for measuring changes in intracellular free calcium concent
rations ([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 r
egions studied, and these responses were blocked by the selective 5-HT2B an
tagonist rauwolscine (1 mu M). The specificity of the responses to alpha-me
thyl 5-HT was further demonstrated by the failure of 4-(4-fluorobenzoyl)-1-
(4-phenylbutyl)-piperidine oxalate (1 mu M), a specific 5-HT2A/5-HT2C antag
onist, to block these responses. The 5-HT2B-induced increases in [Ca2+](i)
persisted in Ca2+-free buffer, indicating that the increase in [Ca2+](i) re
sults from mobilization of intracellular Ca2+ stores. The expression of 5-H
T2B receptors on astroglial cells was further verified immunohistochemicall
y and by Western blot analysis. These results provide evidence of the exist
ence of 5-HT2B receptors on astrocytes in primary culture. (C) 2000 Publish
ed by Elsevier Science Ltd. All rights reserved.