Doublecortin-expressing cells are present in layer II across the adult guinea pig cerebral cortex: partial colocalization with mature interneuron markers.
Doublecortin-immunoreactive (DCX+) cells were detected across the allo- and neo-cortical regions in the adult guinea pig cerebrum, localized to layer II specifically at its border with layer I. The density of labeled cells declined with age, whereas no apparent apoptotic activity was detectable over the cortex including layer II. DCX+ cells varied in somal size, labeling intensity, nuclear appearance, and complexity of processes. These cells were often arranged in clusters with cells of similar morphology sometimes packed tightly together. They exhibited complete colocalization with polysialylated neural cell adhesion molecule (PSA-NCAM) and neuron-specific type III beta-tubulin (TuJ1). Medium to large-sized DCX+ cells had well-developed neuritic processes, and expressed neuron-specific nuclear protein (NeuN). Large mature-looking cells with weak DCX reactivity invariably displayed heavy NeuN reactivity, implicating a transitional stage of these labeled cells. These "transitional" cells also consistently exhibited weak reactivity for gamma-aminobutyric acid (GABA), glutamate decarboxylase (GAD67), beta-nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and neuronal nitric oxide synthase (nNOS), suggestive of them being young GABAergic/nitrinergic interneurons. Our data indicate that DCX+ cells exist widely in the adult guinea pig cerebral cortex, with a predominant localization in upper layer II. The morphological variation and differential expression of neuronal markers in these cells implicate that they might be developing neurons, and that they are probably differentiating into GABAergic interneurons. This population of cells might be involved in interneuron plasticity in the adult mammalian cerebral cortex.
Xiong
Kun
K
Department of Anatomy, Southern Illinois University School of Medicine, 1135 Lincoln Drive, Carbondale, IL 62901, USA.
Luo
Duan-Wu
DW
Patrylo
Peter R
PR
Luo
Xue-Gang
XG
Struble
Robert G
RG
Clough
Richard W
RW
Yan
Xiao-Xin
XX
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology*; D000089622:Doublecortin Domain Proteins; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006168:Guinea Pigs; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism; D009474:Neurons / Q000145:classification* / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D012794:Sialic Acids / Q000378:metabolism
D000089622:Doublecortin Domain Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D039842:Neural Cell Adhesion Molecule L1; D009479:Neuropeptides; D012794:Sialic Acids; C103469:polysialyl neural cell adhesion molecule; D009252:NADPH Dehydrogenase