Preparation and biological evaluation of radiogallium labeled glucagon for SPECT imaging
In this work, recently prepared (67)Ga-labeled glucagon ((67)Ga-DTPA-GCG) for imaging studies (radiochemical purity > 94%; HPLC, S.A. 296-370 GBq/mM) was used in biological studies. The wild-type rat biodistribution results, 2 h post injection, demonstrated high tissue:muscle ratios for target tissues (liver, kidney, heart, spleen, fat intestine stomach and pancreas), 234, 18.45, 7.12, 1.75, 128.7, 4.9, 6.3 and 1.11, respectively. The tracer binding capacity using freshly prepared rat brain homogenate demonstrated significant specific binding of the tracer to neuronal GCG receptors ((67)Ga-DTPA-GCG/(67)Ga:3 and (67)Ga-DTPA-GCG/(67)GaDTPA:2.2 at 90 min). SPECT images also demonstrated target specific binding of the tracer at 4 h. The data suggests the tracer is accumulated in GCGR rich tissues 2-4 h post injection, suggesting potentials of the tracer for future imaging studies in glocagonoma models.