Doublecortin expression in adult cat and primate cerebral cortex relates to immature neurons that develop into GABAergic subgroups.
DCX-immunoreactive (DCX+) cells occur in the piriform cortex in adult mice and rats, but also in the neocortex in adult guinea pigs and rabbits. Here we describe these cells in adult domestic cats and primates. In cats and rhesus monkeys, DCX+ cells existed across the allo- and neocortex, with an overall ventrodorsal high to low gradient at a given frontal plane. Labeled cells formed a cellular band in layers II and upper III, exhibiting dramatic differences in somal size (5-20 microm), shape (unipolar, bipolar, multipolar and irregular), neuritic complexity and labeling intensity. Cell clusters were also seen in this band, and those in the entorhinal cortex extended into deeper layers as chain-like structures. Densitometry revealed a parallel decline of the cells across regions with age in cats. Besides the cellular band, medium-sized cells with weak DCX reactivity resided sparsely in other layers. Throughout the cortex, virtually all DCX+ cells co-expressed polysialylated neural cell adhesion molecule. Medium to large mature-looking DCX+ cells frequently colocalized with neuron-specific nuclear protein and gamma-aminobutyric acid (GABA), and those with a reduced DCX expression also partially co-labeled for glutamic acid decarboxylase, parvalbumin, calbindin, beta-nicotinamide adenine dinucleotide phosphate diaphorase and neuronal nitric oxide synthase. Similar to cats and monkeys, small and larger DCX+ cells were detected in surgically removed human frontal and temporal cortices. These data suggest that immature neurons persist into adulthood in many cortical areas in cats and primates, and that these cells appear to undergo development and differentiation to become functional subgroups of GABAergic interneurons.
Cai
Yan
Y
Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan 410013, China.
Xiong
Kun
K
Chu
Yaping
Y
Luo
Duan-Wu
DW
Luo
Xue-Gang
XG
Yuan
Xian-Yui
XY
Struble
Robert G
RG
Clough
Richard W
RW
Spencer
Dennis D
DD
Williamson
Anne
A
Kordower
Jeffrey H
JH
Patrylo
Peter R
PR
Yan
Xiao-Xin
XX
D000328:Adult; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002415:Cats; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D002648:Child; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008875:Middle Aged; D009249:NADP / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000145:classification / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
C000714328:DCX protein, human; C000714847:Dcx protein, mouse; C000714848:Dcx protein, rat; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009249:NADP; D005680:gamma-Aminobutyric Acid; D052248:Nitric Oxide Synthase Type I