Spatiotemporal patterns of postsynaptic density (PSD)-95 expression after rat spinal cord injury.
OBJECTIVE
Postsynaptic density (PSD)-95 is a scaffolding protein linking the N-methyl-D-aspartate receptor with neuronal nitric oxide synthase (nNOS), which contributes to many physiological and pathological actions. We here investigated whether PSD-95 was involved in the secondary response following spinal cord injury (SCI).


METHODS
Spinal cord contusion (SCC) and spinal cord transection (SCT) models at thoracic (T) segment 9 (T(9)) were established in adults rats. Real-time polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence were used to detect the temporal profile and spatial distribution of PSD-95 after SCI. The association between PSD-95 and nNOS in the injured cords was also assessed by coimmmunoprecipation and double immunofluorescent staining.


RESULTS
The mRNA and protein for PSD-95 expression were significantly increased at 2 h or 8 h, and then gradually declined to the baseline level, ultimately up-regulated again from 5 days to 7 days for its mRNA level and at 7 days or 14 days for its protein level after either SCC or SCT. PSD-95 immunoreactivity was found in neurones, oligodendrocytes and synaptic puncta of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of PSD-95 was colabelled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocytes) and nNOS.


CONCLUSIONS
Accompanied by the spatio-temporal changes for PSD-95 expression, the association between PSD-95 and nNOS undergoes substantial alteration after SCI. These two molecules are likely to form a complex on apoptotic neurones and pathological oligodendrocytes, which may in turn be involved in the secondary response after SCI.
Cheng
C
C
The Jiangsu Province Key Laboratory of Neuroregeneration, Department of Microbiology and Immunology, Nantong University (Former Nantong Medical College), Nantong, China.
Gao
S
S
Zhao
J
J
Niu
S
S
Chen
M
M
Li
X
X
Qin
J
J
Shi
S
S
Guo
Z
Z
Shen
A
A
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000096:biosynthesis*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology*
D000911:Antibodies, Monoclonal; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C085348:tau-1 monoclonal antibody; D052248:Nitric Oxide Synthase Type I; D053148:Caspase 3