Electrophysiological properties of cultured neonatal rat dorsal horn neurons containing GABA and met-enkephalin-like immunoreactivity.
We have developed a culture of neurons dissociated from the most superficial laminae of the neonatal rat spinal cord dorsal horn (DH). By using the perforated patch-clamp technique, we distinguished four types of neurons based on their firing properties in response to intracellular injection of 900 ms lasting current pulses. Type 1 neurons were characterized by a tonic firing. Type 2 neurons displayed marked spike accommodation and fired brief (<500 ms) bursts of action potentials, whereas type 3 neurons fired a single spike. Type 4 neurons exhibited different types of firing patterns, but all of them possessed a time-dependent inwardly rectifying current activated by membrane hyperpolarization. Met-enkephalin-like immunoreactivity (met-ENK-LI) and glutamic acid decarboxylase-like immunoreactivity (GAD-LI) were colocalized in 42% of the neurons (n = 59), which were previously identified electrophysiologically. Type 1-4 neurons represented respectively 4, 64, 20, and 12% of the population of neurons colocalizing met-ENK-LI and GAD-LI. We conclude that the electrophysiological properties of DH neurons present in our cultures are similar to those described in acute slice or hemisected spinal cord preparations and that met-ENK-LI and GABA-LI are preferentially colocalized in type 2 neurons.
Jo
Y H
YH
Laboratoire Neurophysiologie Cellulaire et Intégrée, Unité Mixte de Recherche 7519 Centre National de la Recherche Scientifique, Université Louis Pasteur, 67084 Strasbourg Cedex, France.
Stoeckel
M E
ME
Schlichter
R
R
D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004744:Enkephalin, Methionine / Q000032:analysis*; D005968:Glutamate Decarboxylase / Q000032:analysis; D007150:Immunohistochemistry; D008564:Membrane Potentials; D009474:Neurons / Q000145:classification / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D005680:gamma-Aminobutyric Acid; D004744:Enkephalin, Methionine; D005968:Glutamate Decarboxylase