Involvement of spinal glia in tetanically sciatic stimulation-induced bilateral mechanical allodynia in rats

The previous study showed involvement of spinal glia in tetanically sciatic stimulation-induced long-term potentiation (LTP) of C-fiber-evoked field potentials in the spinal dorsal horn. In the present study, the electrophysiological recording and paw withdrawal threshold (PWT) to von Frey stimulation were assessed following unilaterally tetanically sciatic stimulation in rats. Tetanic stimuli elicited LTP of both A- and C-fiber-evoked field potentials. After stimulation with the same parameter, bilateral PWTs to mechanical stimuli decreased. Intrathecal administration of fluorocitrate (1 nmol/10 microl), an astrocyte inhibitor, partially inhibited tetanic stimulation-induced reduction of bilateral PWTs. A similar effect also occurred at the contralateral side. And this bilateral inhibition of mechanical threshold lasted 8 days. Similarly, intrathecal administration of d-amino acid oxygenase (50 microg/mul, 10 microl), D-serine inhibitor, partially inhibited tetanic sciatic stimulation-induced reduction of bilateral PWTs for 24 h. The results showed that spinal glia plays an important role in bilaterally mechanical allodynia by tetanic sciatic stimulation of the sciatic nerve.