PTX-sensitive regulation of neurite outgrowth by the dopamine D3 receptor.

Neurotransmitter receptors are known to have direct roles in the modulation of neuronal morphogenesis. Previous work showed that clonal mesencephalic MN9D cells individually transfected with D2-like dopamine receptors show increased neurite outgrowth following long-term exposure to the D2-like receptor agonist quinpirole. In the current study, brief stimulation of D3 receptor-expressing cells also elicited increased neurite outgrowth, which could be mimicked by the Gi/G(o) protein activator mastoparan. Pretreatment with the Gi/G(o) protein inhibitor pertussis-toxin blocked the quinpirole- and mastoparan-mediated increases in outgrowth. These results suggest that dopamine D3 receptor stimulation has an immediate, G-protein-mediated role in neuronal morphogenesis.