Histamine H1 receptors in UC-11MG astrocytes and their regulation of cytoplasmic Ca2+.
Experiments were carried out on UC-11MG human astrocytoma cells, a continuous cell line that expresses a broad range of the biochemical and electrophysiological properties found in well-differentiated astrocytes. Because of a number of recent reports that astrocytes may express receptors for a variety of neuro-active substances, we measured the effects of 12 different neurotransmitters on intracellular free Ca2+ (Ca2+i) in UC-11MG cells. Of these neurotransmitters only histamine was found to have a significant effect. Further characterization of the nature of the histamine response showed that UC-11MG cells express mepyramine-sensitive H1 receptors the activation of which causes both mobilization of Ca2+ from intracellular stores and entry of Ca2+ from the extracellular solution. No evidence was found for the presence of H2 receptors. The Ca2+i response was maximal at 300 microM histamine and was attenuated by increasing cell density. We suggest that this neurotransmitter may play a role in astrocytic function in the human CNS.
Lucherini
M J
MJ
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, OH 45220-0524.
Gruenstein
E
E
D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002452:Cell Count; D003593:Cytoplasm / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D011969:Receptors, Histamine H1 / Q000378:metabolism* / Q000502:physiology; D014407:Tumor Cells, Cultured
D011969:Receptors, Histamine H1; D004533:Egtazic Acid; D002118:Calcium