Identification of neuropeptide Y receptors in cultured astrocytes from neonatal rat brain.
Specific binding sites for neuropeptide Y could be demonstrated in primary cultures of astrocytes from neonatal rat brain. Neuropeptide Y binding was saturable, reversible, and temperature dependent as revealed by saturation studies and kinetic experiments. Scatchard analysis of equilibrium binding data indicated a single population of high-affinity binding sites with respective KD and Bmax values of 0.43 nM and 6.9 fmol/2.7 x 10(5) cells. Physiological responses induced by neuropeptide Y could be detected in a distinct subpopulation of cultured astrocytes on the basis of two criteria: 1) electrophysiological responses and 2) single cell measurements of changes in [Ca2+]i. In that fraction of cells responding (20-70%, varying among cultures from different preparations), brief application of neuropeptide Y led to a membrane potential depolarization, lasting several minutes. When the membrane was clamped close to the resting membrane potential using the whole-cell patch-clamp technique, neuropeptide Y induced an inward current with a similar time course as the neuropeptide Y-induced membrane depolarization. As detected by single cell microfluorimetric (fura-2) measurements neuropeptide Y induced an increase of [Ca2+]i which was caused by the entry of extracellular Ca2+. Both the [Ca2+]i increase and the electrophysiological responses were unaffected by pretreatment of the astrocytes with pertussis toxin.
Gimpl
G
G
Department of Neurobiology, University of Heidelberg, Federal Republic of Germany.
Kirchhoff
F
F
Lang
R E
RE
Kettenmann
H
H
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000166:cytology*; D001923:Brain Chemistry / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004594:Electrophysiology; D019204:GTP-Binding Proteins / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017476:Receptors, Neuropeptide Y / Q000302:isolation & purification / Q000378:metabolism*
D007457:Iodine Radioisotopes; D017476:Receptors, Neuropeptide Y; D000246:Adenosine Diphosphate Ribose; D019204:GTP-Binding Proteins; D002118:Calcium