α-Conotoxin AuIB is a conotoxin that has been found in C. aulicus and has receptor antagonist and analgesic activity.1 It is a peptide antagonist of α3β4 subunit-containing nicotinic acetylcholine receptors (nAChRs; IC50 = 0.75 µM). It is greater than 100-fold selective for α3β4 subunit-containing nAChRs over those containing α2β2, α2β4, α3β2, α4β2, α4β4, or α1β1γδ subunits but does inhibit homomeric α7 nAChRs by 34% at 3 µM. Intrathecal administration of α-conotoxin AuIB (0.2 and 2 nmol/animal) reduces mechanical allodynia in a rat model of neuropathic pain induced by partial sciatic nerve ligation.2 It also reverses somatic signs of withdrawal in a mouse model of morphine withdrawal when administered intracerebroventricularly at doses of 1.75 and 3.5 pmol/animal.3
1.Luo, S., Kulak, J.M., Cartier, G.E., et al.α-Conotoxin AuIB selectively blocks α3 β4 nicotinic acetylcholine receptors and nicotine-evoked norepinephrine releaseJ. Neurosci.18(21)8571-8579(1998) 2.Napier, I.A., Klimis, H., Rycroft, B.K., et al.Intrathecal α-conotoxins Vc1.1, AuIB and MII acting on distinct nicotinic receptor subtypes reverse signs of neuropathic painNeuropharmacology62(7)2202-2207(2012) 3.Muldoon, P.P., Jackson, K.J., Perez, E., et al.The α3β4* nicotinic ACh receptor subtype mediates physical dependence to morphine: mouse and human studiesBr. J. Pharmacol.171(16)3845-3857(2014)