In vivo binding of the dopamine-1 receptor PET tracers [11C]NNC112 and [11C]SCH23390: a comparison study in individuals with schizophrenia

Rationale

A deficit in dopamine-1 (D₁) receptor function in the prefrontal cortex is suggested to play a role in the cognitive dysfunction observed in patients with schizophrenia. However, the results from positron emission tomography imaging studies of D₁ receptor levels in individuals with schizophrenia are mixed.

Objectives

The aim of this investigation was to determine whether the in vivo characteristics of the different D₁ receptor tracers used in previous reports, ¹¹C]SCH23390 and ¹¹C]NNC112, may have contributed to these discrepancies reported in the literature.

Methods

Eight patients with schizophrenia and 12 healthy control subjects were scanned with both ¹¹C]SCH23390 and ¹¹C]NNC112.

Results

¹¹C]SCH23390 and ¹¹C]NNC112 binding potentials in both patients and control subjects were compared and no tracer by diagnosis interactions were observed.

Conclusions

The results of this study suggest that differences in the binding of ¹¹C]SCH23390 and ¹¹C]NNC112 observed in previous studies are not due to differences in the in vivo behavior of these tracers.