In the 3 May Nature Oliver Guillin and colleagues report that the expression of the dopamine D₃ receptor is regulated by the brain-derived neurotrophic factor (BDNF), a protein once thought to be needed simply for the proliferation and survival of neurons (Nature 2001, 411:86-89).

D₃ receptors are expressed mainly in an area of the brain known as the shell of the nucleus accumbens. Neurons from the ventral tegmental area (VTA), which produce both dopamine and BDNF, connect to neurons of the nucleus accumbens. Guillin et al show that in gene-targeted mice lacking BDNF, or in a rat model of Parkinson's disease (in which the dopamine-releasing neurons of the VTA are damaged by infusion of 6-hydroxydopamine), D₃ receptors are not expressed in the nucleus accumbens shell. Infusion of BDNF into the shell restored the expression of the D₃ receptor.

In the rat model dopamine-releasing neurons...