Bilateral modulation of [3H]neurotensin binding by unilateral intrastriatal 6-hydroxydopamine injections: evidence from a receptor autoradiographic study.

The present study was carried out in order to re-evaluate the issue of the localization of neurotensin receptors in the caudate-putamen and in the nucleus accumbens of rat. Intrastriatal injections of 6-hydroxydopamine which cause almost complete destruction of the mesostriatal dopaminergic pathway also caused a marked loss of neurotensin receptors in the caudate-putamen (CPu), the nucleus accumbens (NAc) and in the olfactory tubercle (OT). These decreases corresponded to a mean loss of 98, 93 and 41% in the CPu, the NAc, and the OT, respectively. There were corresponding decreases in the substantia nigra pars compacta (SNpc) (-94%) and pars reticulata (SNpr) (-97%), and in the ventral tegmental area (-78%). Moreover, there were also decreases in neurotensin receptors on the contralateral side of the intrastriatal injections which occurred in the CPu but not in the NAc nor in the OT. These results indicate that almost all NT receptors measured within the CPu and the NAc are located on the terminals of dopaminergic neurons within those structures. The bilaterality of the changes which occur in the CPu provide further support for the notion of the interdependence of the two nigrostriatal dopaminergic projections and the peptidergic systems with which they interact.