Spiny projection neuron dopamine receptors

In the light of our data showing LTP to be dopamine-dependent, it seems likely that the facilitation of LTP in Mg-free conditions may be brought about by increased HFS-induced release of dopamine. Increased dopamine release occurs in Mg++-free solution due to activation of presynaptic NMDA receptors, presumably located on dopaminergic nerve terminals (Roberts and Sharif, 1978 Krebs et al., 1991a,b Desce et al., 1992). As noted above, the dopaminergic terminals on spiny projection neurons synapse in close... 

Dopamine acts on G-protein-coupled receptors belonging to the D1 -family of receptors (so-called D1-like receptors , or DlLRs, comprised of Dl- and D5-receptors), and the D2-family of receptors ( D2-like receptors , or D2LRs comprised of D2-, D3- and D4-receptors). Dl LRs stimulate adenylate cyclase activity and, possibly, also phosphoinosit-ide hydrolysis, while D2LRs reduce adenylate cyclase activity. In the striatum, DlLRs are predominately associated with medium spiny neurons of the direct pathway, while D2LRs have been found as autoreceptors on dopaminergic terminals, as heteroreceptors on cholinergic interneurons, and on indirect pathway neurons. In the SNr, DlLRs are located on terminals of the direct pathway projection, while D2LRs appear to function as autoreceptors. 

CBi receptors are also expressed at low to moderate levels in the nucleus accumbens. Here CBi receptors are found in a pattern reminiscent of the striatum. CBi receptors are expressed on terminals of the glutamatergic prefrontal cortex accumbens pathways (Robbe et al. 2001). They are also present on the accumbens medium spiny neurons. They appear to be absent from the dopaminergic terminals projecting to the accumbens from the ventral tegmentum. Consequently, cannabinoid stimulation of dopamine release in nucleus accumbens (Tanda et al. 1997) appears to be an indirect effect, perhaps mediated by inhibition of GABA release (Szabo et al. 1999,2002). 

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