Activation of Spinal α2-Adrenoceptors Using Diluted Bee
Venom Stimulation Reduces Cold Allodynia in Neuropathic Pain Rats
Evid Based Complement Alternat Med, 2012 Aug 27
Cold allodynia is an important distinctive feature of
neuropathic pain.
The present study examined whether single or repetitive
treatment of diluted bee venom (DBV) reduced cold allodynia in sciatic nerve
chronic constriction injury (CCI) rats and whether these effects were mediated
by spinal adrenergic receptors.
Single injection of DBV (0.25 or 2.5 mg/kg) was performed
into Zusanli acupoint 2 weeks post CCI, and repetitive DBV (0.25 mg/kg) was
injected for 2 weeks beginning on day 15 after CCI surgery. Single treatment of
DBV at a low dose (0.25 mg/kg) did not produce any anticold allodynic effect,
while a high dose of DBV (2.5 mg/kg) significantly reduced cold allodynia.
Moreover, this effect of high-dose DBV was completely blocked by intrathecal
pretreatment of idazoxan (α2-adrenoceptor antagonist), but not prazosin
(α1-adrenoceptor antagonist) or propranolol (nonselective β-adrenoceptor
antagonist). In addition, coadministration of low-dose DBV (0.25 mg/kg) and
intrathecal clonidine (α2-adrenoceptor agonist) synergically reduced cold
allodynia. On the other hand, repetitive treatments of low-dose DBV showing no
motor deficit remarkably suppressed cold allodynia from 7 days after DBV
treatment. This effect was also reversed by intrathecal idazoxan injection.
These findings demonstrated that single or repetitive
stimulation of DBV could alleviate CCI-induced cold allodynia via activation of
spinal α2-adrenoceptor.
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