Antinociceptive effects of intrathecally administered huwentoxin-I, a selective N-type calcium channel blocker, in the formalin test in conscious rats.
The present study was undertaken to elucidate the antinociceptive effect of intrathecal administration of huwentoxin-I (HWTX-I), a N-type calcium channel blocker from the venom of the Chinese bird spider Ornithoctonus huwena (Wang) [=Selenocosmia huwena wang], by comparison with omega-Conotoxin-MVIIA (omega-CTX-MVIIA) and morphine hydrochloride in the formalin test in conscious rats. Similar to omega-CTX-MVIIA and morphine, intrathecal pre-treatment with HWTX-I resulted in suppression of nociceptive behavior in a dose-dependent manner. The ED50 values of HWTX-I and omega-CTX-MVIIA were 0.28 and 0.19 microg/kg, respectively. It was also found that, at lower doses (0.1 and 0.5 microg/kg), the antinociceptive effect of HWTX-I was identical to that of omega-CTX-MVIIA, while omega-CTX-MVIIA acted more remarkably than HWTX-I at higher dose (1.0 microg/kg). However, the antinociception induced by omega-CTX-MVIIA were companied with motor dysfunction, and these side-effects became more evident with the doses of omega-CTX-MVIIA increasing. In contrast, HWTX-I did not show these side-effects at the doses of 0.5-1.0 microg/kg. Compared with HWTX-I and omega-CTX-MVIIA, the analgesic effect of intrathecal morphine hydrochloride was initiated faster, but lasted for a shorter time (about 2-3 h at 1.0 microg/kg) than that of HWTX-I and omega-CTX-MVIIA (about 4- 5 h at 1.0 microg/kg). Therefore, the present results show that, like omega-CTX-MVIIA, the intrathecal administration of HWTX-I is effective in antinociception in the rat model of the formalin test.
Chen
Jia-Qin
JQ
Biochemistry Department, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, People's Republic of China.
Zhang
Yong-Quen
YQ
Dai
Jie
J
Luo
Zhuo-Min
ZM
Liang
Song-Ping
SP
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005557:Formaldehyde; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009498:Neurotoxins / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D030162:Reptilian Proteins; D013111:Spider Venoms / Q000008:administration & dosage / Q000494:pharmacology*; D020960:omega-Conotoxins / Q000494:pharmacology
D000700:Analgesics; D002121:Calcium Channel Blockers; D009498:Neurotoxins; D030162:Reptilian Proteins; D013111:Spider Venoms; C083624:huwentoxin I; D020960:omega-Conotoxins; D005557:Formaldehyde; D009020:Morphine; C078452:ziconotide