抄録
The potential role of nicotinic acetylcholine receptors (nAChR) in modulating numerous physiological actions has been recently elucidated. The nAChRs are considered as novel therapeutic targets for learning, development and aging as well as analgesia. However, the antinociceptive action of nAChRs in spinal cord is yet to be confirmed. In order to determine which subtypes of nAChRs are involved in antinociception, we examined the roles of nAChRs in modulating inhibitory synaptic transmission in dorsal horn neurons by using patch-clamp recordings from spinal cord slice preparations. Bath application of nicotine enhanced GABAergic/glycinergic IPSCs in both superficial and deep spinal dorsal horn neurons. When β4 nAChRs agonist cyticine was applied, GABAergic/glycinergic IPSCs were significantly increased in superficial dorsal horn neurons, but failed to be increased in deep dorsal horn neurons. On the other hand, when we applied α4β2 nAChRs agonist RJR-2403 or α7 nAChRs agonist Choline, IPSCs were not increased in superficial dorsal horn neurons, but largely increased in deep dorsal horn neurons. These results indicate that distinct subtypes of nAChRs are expressed in inhibitory interneurons of spinal dorsal horn and facilitate GABA/glycine release. These specific nAChRs expression in spinal inhibitory interneurons may contribute to the unserstanding of the mechanism of nicotine-induced antinociception. [Jpn J Physiol 54 Suppl:S172 (2004)]
