F-FP-CIT dopamine transporter PET findings in the striatum and retina of type 1 diabetic rats.

Purpose: Noninvasive methods used in clinic to accurately detect DA neuron loss in diabetic brain injury and diabetic retinopathy have not been reported up to now. F-FP-CIT is a promising dopamine transporter (DAT) targeted probe. Our study first applies F-FP-CIT PET imaging to assess DA neuron loss in the striatum and retina of T1DM rat model.

Methods: T1DM rat model was induced by a single intraperitoneal injection of streptozotocin (STZ) (65 mg kg, ip). F-FP-CIT uptake in the striatum and retina was evaluated at 4 weeks, 8 weeks and 12 weeks after STZ injection. The mean standardized uptake value (SUVmean) and the maximum standardized uptake value (SUVmax) were analyzed. Western blot was performed to confirm the DAT protein levels in the striatum and retina.

Results: PET/CT results showed that the SUV of F-FP-CIT was significantly reduced in the diabetic striatum and retina compared with the normal one from 4-week to 12-week (p < 0.0001). Western blots showed that DAT was significantly lower in the diabetic striatum and retina compared to the normal one for all three time points (p < 0.05). The results from Western blots confirmed the findings in PET imaging studies.

Conclusions: DA neuron loss in the striatum and retina of T1DM rat model can be non-invasively detected with PET imaging using F-FP-CIT targeting DAT. F-FP-CIT PET imaging may be a useful tool used in clinic for DR and diabetic brain injury diagnosis in future. The expression level of DAT in striatum and retina may act as a new biomarker for DR and diabetic brain injury diagnosis.