Biochemical characterization of particles from rat striatum containing dopamine, cholecystokinin or both

Cholecystokinin (CCK) containing particles were isolated from rat striatum. After differential and isopycnic sucrose density gradient centrifugation, CCK containing particles equilibrated around 1.2 M sucrose. Dopamine (DA) containing particles equilibrated around the same buoyant density, but the colocalization of a cytosolic as well as a mitochondrial enzyme marker and the low enrichment at this density indicated an incomplete isolation of CCK containing particles from other subcellular organelles. Alternatively, differential centrifugation and gel filtration on Sephacryl S-1000 did yield advanced isolation of CCK containing vesicles. These vesicles also contain particle-bound DA. During hypo-osmotic lysis, these CCK and/or DA containing particles behaved like synaptic vesicles. Therefore, it was concluded that CCK containing vesicles from rat corpus striatum were indeed isolated and characterized and that the same or similar vesicles contain DA as well as CCK.