Effects of Quinolinate-Induced Lesion of the Medial Prefrontal Cortex on Prefrontal and Striatal Concentrations of D-Serine in the Rat.

ABSTRACT

D-Serine has been shown to play an important role in the expression and control of a variety of brain functions by acting as the endogenous coagonist for the N-methyl-D-aspartate type glutamate receptor (NMDAR), at least, in the forebrain. To obtain further insight into the still debatable cellular localization of the D-amino acid, we have examined the effects of the selective destruction of the neuronal cell bodies by quinolinate on the tissue or extracellular D-serine concentrations in the medial prefrontal cortex of the rat. A local quinolinate infusion into the bilateral medial prefrontal cortex produced a cortical lesion with a marked (- 65%) and non-significant alteration (- 5%) in the cortical and striatal tissue D-serine concentrations, respectively, 7 days post-infusion. In vivo microdialysis experiments in the right prefrontal lesion site 9 days after the quinolinate application revealed that the basal extracellular D-serine levels were also dramatically reduced (- 64%). A prominent reduction in the tissue levels of GABA in the interneurons of the prefrontal cortex (- 78%) without significant changes in those in the striatum (+ 12%) verified that a major lesion part was confined to the cortical portion. The lack of a significant influence of the prefrontal quinolinate lesion on its dopamine concentrations in the mesocortical dopamine projections suggests that the nerve terminals and axons in the lesion site may be spared. These findings are consistent with the perikarya-selective nature of the present quinolinate-induced lesion and further support the view that neuronal cell bodies of intrinsic neurons in the prefrontal cortical region contain substantial amounts of D-serine, which may sustain the basal extracellular concentrations of D-serine.