Dopamine D2-like receptor binding in the brain of male Japanese quail (Coturnix japonica)

Japanese quail (Coturnix japonica) have been used extensively to study appetitive behaviors. However, little is known about the appetitive-relevant neurochemical systems in this species. The present investigation examined the distribution of D-2-like dopamine receptors in the quail brain. [H-3]Spiperone was incubated in brain tissue homogenates and nonspecific binding was defined using (-)-sulpiride. Scatchard analysis of whole brain without cerebellum and forebrain alone indicated approximate K-d's of 0.08 and 0.04 nM, respectively, in addition, the preferential D-3 agonist (+/-)-2-dipropylamino-7-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (7-OH-DPAT) did not displace [H-3]spiperone binding in quail forebrain. Finally, regional analysis showed that the highest densities of D-2-like receptors were located in the forebrain. Overall, these results indicate that there is some conservation of dopaminergic mechanisms between aves and mammals. Thus, Japanese quail may be useful for examining the neuropharmacological mechanisms of dopaminergic stimulant drugs that work via D-2-like receptor activation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.