Neurochemical characterization of tyrosine hydroxylase-immunoreactive interneurons in the developing rat cerebral cortex.
Understanding the development of cortical interneuron phenotypic diversity is critical because interneuron dysfunction has been implicated in several neurodevelopmental disorders. Here, tyrosine hydroxylase (TH)-immunoreactive neurons in the developing and adult rat cortex were characterized in light of findings regarding interneuron neurochemistry and development. Cortical TH-immunoreactive neurons were first observed 2 weeks postnatally and peaked in number 3 weeks after birth. At subsequent ages, the number of these cell profiles was gradually reduced, and they were seen less frequently in adults. No DNA fragmentation or active caspase 3 was observed in cortical TH cells at any age examined, eliminating cell death as an explanation for the decrease in cell number. Although cortical TH cells reportedly fail to produce subsequent catecholaminergic enzymes, we found that the majority of these cells at all ages contained phosphorylated TH, suggesting that the enzyme may be active and producing L-DOPA as an end-product. Morphological criteria and colocalization of some TH cells with glutamic acid decarboxylase suggest that these cells are interneurons. Previously, parvalbumin, somatostatin, and calretinin were demonstrated in non-overlapping subsets of interneurons. Cortical TH neurons colocalized with calretinin but not with parvalbumin or somatostatin. These findings suggest that the transitory increase in TH cell number is not due to cell death but possibly due to alterations in the amount of detectable TH present in these cells, and that at least some cortical TH-producing interneurons belong to the calretinin-containing subset of interneurons that originate developmentally in the caudal ganglionic eminence.
Asmus
Stephen E
SE
Biochemistry/Molecular Biology and Biology Programs, Centre College, 600 W. Walnut Street, Danville, KY 40422, USA. steve.asmus@centre.edu
Anderson
Emily K
EK
Ball
Mark W
MW
Barnes
Brock A
BA
Bohnen
Angela M
AM
Brown
Alexander M
AM
Hartley
Lucinda J
LJ
Lally
Matthew C
MC
Lundblad
Tammy M
TM
Martin
Joshua B
JB
Moss
Benjamin D
BD
Phelps
Kevin D
KD
Phillips
Laura R
LR
Quilligan
Cara G
CG
Steed
Ryan B
RB
Terrell
Shariya L
SL
Warner
Ashley E
AE
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D053148:Caspase 3 / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007395:Interneurons / Q000378:metabolism*; D008297:Male; D010320:Parvalbumins / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D010320:Parvalbumins; D014446:Tyrosine 3-Monooxygenase; D053148:Caspase 3; D005968:Glutamate Decarboxylase