Neurochemical and electrophysiological evidence for the existence of a functional gamma-hydroxybutyrate system in NCB-20 neurons

Neuroscience. 1998 Oct;86(3):989-1000. doi: 10.1016/s0306-4522(98)00085-2.


Clonal neurohybridoma NCB-20 cells express a valproate-insensitive succinic semialdehyde reductase activity that transforms succinic semialdehyde into gamma-hydroxybutyrate. This activity (1.14+/-0.16 nmol/min/mg protein) was similar to the lowest activity existing in adult rat brain. [3H]gamma-Hydroxybutyrate labels a homogeneous population of sites on NCB-20 cell membranes (Kd=250+/-44.4nM, Bmax=180+/-16.2fmol/mg protein) that apparently represents specific gamma-hydroxybutyrate binding sites characterized previously on brain cell membranes. Finally, an Na+-dependent uptake of [3H]gamma-hydroxybutyrate was expressed in NCB-20 cells with a Km of 35+21.1 microM and a Vmax of 80+/-14.2 pmol/min/mg protein. A three-day treatment with 1 mM dibutyryl-cyclic-AMP induced a three-fold increase in the cellular succinic semialdehyde reductase activity. In parallel, a K+-evoked release of [3H]gamma-hydroxybutyrate occurred. This release was Ca2+ dependent and was not present in undifferentiated cells. Cyclic-AMP treatment induced a decrease of [3H]gamma-hydroxybutyrate binding sites, which could be due to spontaneous gamma-hydroxybutyrate release. Patch-clamp experiments carried out on differentiated NCB-20 cells revealed the presence of Ca2+ conductances which were partially inhibited by 50 microM gamma-hydroxybutyrate. This gamma-hydroxybutyrate-induced effect was blocked by the gamma-hydroxybutyrate receptor antagonist NCS-382, but not by the GABA(B) antagonist CGP-55845. These results demonstrate the presence of an active gamma-hydroxybutyratergic system in NCB-20 cells which possesses the ability to release gamma-hydroxybutyrate. These cells express specific gamma-hydroxybutyrate receptors which modulate Ca2+ currents independently of GABA(B) receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Biological Transport
  • Brain / enzymology
  • Calcium / metabolism
  • Calcium Channels / physiology*
  • Cell Line
  • Cricetinae
  • Cricetulus
  • Hybridomas
  • Hydroxybutyrate Dehydrogenase / metabolism*
  • Immunohistochemistry
  • Kinetics
  • Membrane Potentials
  • Mice
  • Neuroblastoma
  • Neurons / physiology*
  • Patch-Clamp Techniques
  • Rats
  • Sodium Oxybate / metabolism*
  • Valproic Acid / pharmacology


  • Calcium Channels
  • Valproic Acid
  • Sodium Oxybate
  • Hydroxybutyrate Dehydrogenase
  • 4-hydroxybutyrate dehydrogenase
  • Calcium