Effect of L-cycloserine on cortical neurons in the rat

L-Cycloserine but not D-cycloserine, depressed the firing of neurons in the sensorimotor cortex of the rat with a relatively slow time course when administered by microionophoresis or i.p. injection. The effects of GABA applied by microionophoresis or released synaptically were not modified by i.p. injections and microionophoretic administration of L-cycloserine. It is concluded that L-cycloserine depresses cell firing not by potentiation of the action of GABA but by elevating GABA-levels.