Effects of intrathecally administerd NaV1.8 Antisense oligonucleotide on the expression of sodium channel mRNA in dorsal root ganglion

Abstract

Neuropathic pain has been hypothesized to be the result of aberrant expression and function of sodium channels at the site of injury. To investigate the effects of NaV1.8 antisense oligonucleotide on the expression of sodium channel mRNA in dorsal root ganglion (DRG) neurons in chronic neuropathic pain. 24 Sprague-Dawley rats weighing 200–260 g were anesthetized with the intraperitoneal injection of 300 mg·kg⁻¹ choral hydrate. The CCI model was made by loose ligation of sciatic nerve trunk by 4-0 chromic gut. The mechanical and thermal pain threshold were measured before operation and 1, 3, 5, 7, 9, 11, 13 days after operation. A PE-10 catheter was implanted in subarachnoid space at lumbar region. On the 7th postoperative day the animals were randomly divided into 4 groups. The drugs were injected intrathecally twice a day for 5 consecutive days in group 2–4. The animals were decapitated 14 days after the surgery. The L4–L6 DRG of the operated side was removed and crushed, and total RNA was extracted with Trizol reagent. The contralateral side was used as control. The change of NaV1.8 sodium channel transcripts was determined by RT-PCR. Pain threshold was significantly lowered after CCI as compared with that in control group and was elevated 3 days after antisense oligonucleotide injection. Sensory neuron specific TTX-R sodium channel NaV1.8 transcript was down-regulated after antisense oligonucleotide injection at the dosage of 45 μg as compared with that in CCI group (P<0.01), and it was even greater at the dosage of 90 μg. The intrathecally injected NaV1.8 antisense oligonucleotide can reduce the mechanical allodynia and thermal hyeralgesia partially by downregulating the SNS transcript expression.

Keywords

tetrodotoxin-resistant sodium channel current / neuropathic pain / antisense / dorsal root ganglion / sensory neurons / voltage sensing sodium channel type 1.8 (NaV1.8)

References

[1] BennettG J, XieY K. A peripheral mononeuropathy in rat that produces disorders of pain sensation like those seen in man. Pain, 1988, 33: 87-87

[2] ZhaoX, LiuJ, XuJ G. Effects of estrogen on thermal hyperalgesia following chronic constrictive nerve injury in rats. Chin J Anesthesiol, 2004, 24(4): 279-279

[3] LaiJ, GoldM S, KimC S, et al. . Inhibition of neuropathic pain by decreased expression of the tetrodotoxin-resistant sodium channel, NaV1.8. Pain, 2002, 95: 143-143

[4] YangJ P, JiangH, WuY. Improvement for the longterm dewelling catherter into subarachnoid space in rats. Chin J Anesthesiol, 1993, 13: 110-110

[5] ChaplanS R, BachF W, PogrelJ W, et al. . Quantitative assessment of tactile allodynia in the rat paw. J Neurosci Methods, 1994, 53: 55-55

[6] HagreavesK, DubnerR, BrownF, et al. . A new and sensitive method for measuring thermal nociception in cutaneous hyperalgesia. Pain, 1988, 32: 77-77

[7] Dib-HajjS D, FjellJ, CumminsT R, et al. . Plasticity of sodium channel expression in DRG neurons in the chronic constriction injury model of neuropathic pain. Pain, 1999, 83: 591-591

[8] PorrecaF, LaiJ, BianD, et al. . A comparison of the potential role of the tetrodotoxin insensitive sodium channels, PN3/SNS and NaN/SNS2, in rat models of chronic pain. Proc Nat Acad Sci USA, 1999, 96(14): 7640-7640

[9] KhasarS G, GoldM S, LevineJ D. A tetrodotoxin-resistant sodium current mediates inflammatory pain in the rat. Neuroscience, 1998, 256: 17-17

[10] OkuseK, ChaplanS R, McMahonS R, et al. . Regulation of expression of the sensory neuron specific sodium channel in the inflammatory and neuropathic pain. Mol Cell Neurosci, 1997, 10: 196-196

[11] NovakovicS D, TzoumakaE, McGivernJ G, et al. . Distribution of the tetrodotoxin-resistant sodium channel PN3 in rat sensory neurons in normal and neuropathic conditions. J Neurosci, 1998, 18(6): 2174-2174

[12] EnglandS, BevanS, DochertyR J. PGE2 modulates the tetrodotoxin-resistant sodium current in neonatal rat dorsal root ganglion neurons via the cyclic AMP-protein kinase A cascade. J Physiol, 1996, 495: 429-429