Characterization and autoradiographic distribution of neurotensin binding sites in the human brain

The characteristics and topographical distribution of monoiodo 125I-Tyr3-neurotensin (NT) binding sites in normal human brain tissue were studied on brain sections and by quantitative autoradiography. Sections at the level of the substantia nigra show a dissociation constant and maximal binding capacity of 4.8 +/- 0.8 nM and 70 +/- 7 fmol/mg protein, respectively. High density of 125I-NT binding sites were mainly found in dopaminergic (DA)-rich areas such as the substantia nigra, the ventral tegmental area, the striatum and the nucleus accumbens, further supporting an interaction between NT and DA neurons in human brain.