D-cycloserine, a positive modulator of the N-methyl-D-aspartate receptor, enhances performance of learning tasks in rats

Pharmacol Biochem Behav. 1989 Nov;34(3):649-53. doi: 10.1016/0091-3057(89)90571-6.


Glycine has recently been shown to positively modulate the N-methyl-D-aspartate (NMDA) subclass of acidic amino acid receptors which are important in neural pathways involved in learning and memory. We report that d-cycloserine (DCS), an antimycobacterial agent known to cross the blood-brain barrier, binds with high affinity to this glycine modulatory site, functions as a positive modulator, and facilitates performance of learning tasks in rats. In addition, DCS appears to be a potent cognitive enhancer at doses lower than those required for antibacterial activity. Based on these data, we propose that modulation of NMDA receptors via glycinergic mechanisms may be a means of influencing cognitive processes.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Avoidance Learning / drug effects
  • Cycloserine / pharmacology*
  • Learning / drug effects*
  • Male
  • Rats
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter / drug effects
  • Receptors, Neurotransmitter / physiology*


  • Anti-Bacterial Agents
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter
  • Cycloserine