Differential regulation of dopamine D1 and D2 signaling by nicotine in neostriatal neurons
Version of Record online: 13 JUL 2004
Journal of Neurochemistry
Volume 90, Issue 5, pages 1094–1103, September 2004
How to Cite
Hamada, M., Higashi, H., Nairn, A. C., Greengard, P. and Nishi, A. (2004), Differential regulation of dopamine D1 and D2 signaling by nicotine in neostriatal neurons. Journal of Neurochemistry, 90: 1094–1103. doi: 10.1111/j.1471-4159.2004.02574.x
- Issue online: 27 JUL 2004
- Version of Record online: 13 JUL 2004
- Received February 16, 2004; revised manuscript received April 17, 2004; accepted April 19, 2004.
- nicotinic acetylcholine receptors;
Nicotine, acting on nicotinic acetylcholine receptors (nAChRs) expressed at pre-synaptic dopaminergic terminals, has been shown to stimulate the release of dopamine in the neostriatum. However, the molecular consequences of pre-synaptic nAChR activation in post-synaptic neostriatal neurons are not clearly understood. Here, we investigated the effect of nAChR activation on dopaminergic signaling in medium spiny neurons by measuring phosphorylated DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of Mr 32 kDa) at Thr34 (the PKA-site) in mouse neostriatal slices. Nicotine produced dose-dependent responses, with a low concentration (1 µm) causing a sustained decrease in DARPP-32 Thr34 phosphorylation and a high concentration (100 µm) causing a transient increase in DARPP-32 Thr34 phosphorylation. Depending on the concentration of nicotine, either dopamine D2 or D1 receptor signaling was predominantly activated. Nicotine at a low concentration (1 µm) activated dopamine D2 receptor signaling in striatopallidal/indirect pathway neurons, likely by activating α4β2* nAChRs at dopaminergic terminals. Nicotine at a high concentration (100 µm) activated dopamine D1 receptor signaling in striatonigral/direct pathway neurons, likely by activating (i) α4β2* nAChRs at dopaminergic terminals and (ii) α7 nAChRs at glutamatergic terminals, which, by stimulating the release of glutamate, activated NMDA/AMPA receptors at dopaminergic terminals. The differential effects of low and high nicotine concentrations on D2- and D1-dependent signaling pathways in striatal neurons may contribute to dose-dependent actions of this drug of abuse.