Functional integration of newly generated neurons into striatum after cerebral ischemia in the adult rat brain.
OBJECTIVE
Ischemic injury can induce neurogenesis in the striatum. Those newborn neurons can express glutamic acid decarboxylase and choline acetyltransferase, markers of GABAergic and cholinergic neurons, respectively. The present study investigated whether these GABAergic and cholinergic new neurons could differentiate into functional cells.


METHODS
Retrovirus containing the EGFP gene was used to label dividing cells in striatal slices prepared from adult rat brains after middle cerebral artery occlusion. EGFP-targeted immunostaining and immunoelectron microscopy were performed to detect whether newborn neurons could anatomically form neuronal polarity and synapses with pre-existent neurons. Patch clamp recording on acute striatal slices of brains at 6 to 8 weeks after middle cerebral artery occlusion was used to determine whether the newborn neurons could display functional electrophysiological properties.


RESULTS
EGFP-expressing (EGFP(+)) signals could be detected mainly in the cell body in the first 2 weeks. From the fourth to thirteenth weeks after their birth, EGFP(+) neurons gradually formed neuronal polarity and showed a time-dependent increase in dendrite length and branch formation. EGFP(+) cells were copositive for NeuN and glutamic acid decarboxylase (EGFP(+)-NeuN(+)-GAD(67)(+)), MAP-2, and choline acetyltransferase (EGFP(+)-MAP-2(+)-ChAT(+)). They also expressed phosphorylated synapsin I (EGFP(+)-p-SYN(+)) and showed typical synaptic structures comprising dendrites and spines. Both GABAergic and cholinergic newborn neurons could fire action potentials and received excitatory and inhibitory synaptic inputs because they displayed spontaneous postsynaptic currents in picrotoxin- and CNQX-inhibited manners.


CONCLUSIONS
Ischemia-induced newly formed striatal GABAergic and cholinergic neurons could become functionally integrated into neural networks in the brain of adult rats after stroke.
Hou
Shang-Wei
SW
Department of Neurobiology, State Key Laboratory of Medical Neurobiology, Shanghai Medical College of Fudan University, Shanghai, PR China.
Wang
Yong-Quan
YQ
Xu
Ming
M
Shen
Di-Han
DH
Wang
Ji-Jiang
JJ
Huang
Fang
F
Yu
Zhang
Z
Sun
Feng-Yan
FY
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation; D002465:Cell Movement / Q000502:physiology; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine