Neurotensin reduces the affinity of dopamine D2 receptors in membranes from post mortem human caudate-putamen.

The effects of neurotensin in vitro were investigated on the binding characteristics of N-[3H]propylnorapomorphine [( 3H]NPA) binding sites in crude membrane preparations from post mortem human caudate-putamen, obtained within 10 h after death from 3 patients without reported neurological or psychiatric diseases. Neurotensin (0.1-30 nM) was found to increase the KD value of [3H]NPA binding sites with a maximal increase of about 50% (420 +/- 45 pM) at 3 nM of neurotensin, without significantly affecting the Bmax value (123 +/- 20 pmol/g protein). These results indicate the existence of an intramembrane regulation by neurotensin receptors of D2 receptors in the human caudate-putamen.