Protein synthesis inhibition blocks the late-phase LTP of C-fiber evoked field potentials in rat spinal dorsal horn.
Previous studies have demonstrated that in the hippocampus the maintenance of long-term potentiation (LTP) requires de novo protein synthesis. To investigate the role of protein synthesis in the maintenance of LTP of C-fiber evoked field potentials in spinal dorsal horn, which may be relevant to hyperalgesia, protein synthesis inhibitor (either cycloheximide or anisomycin) was applied locally to the recording segments of spinal cord in anesthetized rats, 30 min prior to tetanic stimulation to the sciatic nerve. We found that both cycloheximide and anisomycin selectively inhibited late-phase maintenance of the spinal LTP but affected neither LTP induction nor baseline responses of C-fiber evoked field potentials. In the presence of cycloheximide, LTP of C-fiber evoked field potentials was 281.5 +/- 16.5% (n = 6) of baseline 1 h after tetanic stimulation and the potentiation significantly decreased to 235.5 +/- 18.5% at 145 min after tetanic stimulation (P < 0.05). Afterward, LTP of C-fiber evoked field potentials decreased continuously and at 270 min after tetanic stimulation reached 130.8 +/- 18.0%, which was no longer different from baseline (P > 0.05). Spinal application of anisomycin at 30 min before tetanic stimulation yielded similar results (n = 6). These results suggest that protein synthesis may be crucial for the late-phase maintenance of LTP of C-fiber evoked field potentials in spinal dorsal horn.
Department of Physiology, Zhongshan Medical School of Sun Yat-sen University, 74 Zhongshan Rd 2, Guangzhou 510089, People's Republic of China.
Neng-Wei
NW
Hu
Hong-Mei
HM
Zhang
Xiao-Dong
XD
Hu
Ming-Tao
MT
Li
Tong
T
Zhang
Li-Jun
LJ
Zhou
Xian-Guo
XG
Liu
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D020671:Posterior Horn Cells / Q000187:drug effects* / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects
D009419:Nerve Tissue Proteins; D011500:Protein Synthesis Inhibitors; D000841:Anisomycin; D003513:Cycloheximide