Morphological, immunophenotypical and electrophysiological properties of resting microglia in vitro.
Morphological, immunophenotypical and electrophysiological properties were investigated in isolated cultured murine microglia before and after exposure to astrocyte-conditioned medium (ACM). Following application of ACM, microglial cells underwent a dramatic shape transformation from an amoeboid appearance to a ramified morphology. In parallel to morphological changes, a downregulation of macrophage surface antigens was observed in microglia exposed to ACM. Staining intensities for major histocompatibility complex (MHC) class II molecules and for the adhesion molecules leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) were significantly decreased in ramified microglia 5 days after exposure to ACM. In microglial cells treated daily with ACM over a period of 5 days, the smallest staining intensities for all surface antigens as well as the smallest ramification index as a measure for the highest degree of ramification were determined. In addition, upregulation of delayed rectifier K + currents was observed in microglia exposed to ACM for 1 day or treated daily with ACM for 5 days. In contrast, untreated amoeboid microglia or ramified microglia analysed 5 days after exposure to ACM did not express delayed rectifier K + currents. Analyses of the resting membrane potential and expression levels and properties of inward rectifier K + currents did not reveal any differences between untreated and ACM-treated microglia. It is suggested that electrophysiological properties of microglia do not strongly correlate with the morphology or the immunophenotype of microglial cells.
Eder
C
C
Department of Neurophysiology, Institute of Physiology, Humboldt University, Berlin, Germany. claudia.eder@charite.de
Schilling
T
T
Heinemann
U
U
Haas
D
D
Hailer
N
N
Nitsch
R
R
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology; D001464:Barium / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D017628:Microglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated
D015815:Cell Adhesion Molecules; D017077:Culture Media, Conditioned; D051668:Delayed Rectifier Potassium Channels; D000949:Histocompatibility Antigens Class II; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D001464:Barium