LOCALIZATION AND QUANTIFICATION OF CHOLECYSTOKININ RECEPTORS IN RAT-BRAIN WITH STORAGE PHOSPHOR AUTORADIOGRAPHY

The present study evaluated a new imaging technique that demonstrated the application of storage phosphor autoradiography in the localizatio n and quantification of cholecystokinin receptors in rat brains and co mpared the results with film autoradiography. Cryostat sections were i ncubated with [I-125]Bolton-Hunter-labeled sulfated cholecystokinin oc tapeptide followed by exposure to a storage phosphor-imaging screen an d suitable autoradiography film To obtain satisfactory images, it took 6 days with film autoradiography vs. 15 hours with the storage phosph or technique. Both film and storage phosphor autoradiograms showed ril e same cholecystokinin receptor distribution in brain sections; howeve r, the film imaged more details. To reach the lowest possible response ratio between low and high receptor density regions in rat brains, st orage phosphor autoradiography was about 240-fold faster than film In addition, the new technique presented a considerably larger exposure t ime range for maintaining that ratio. The binding per area showed a li near relationship with the thickness of sections between 5 and 14 mu m . In the linear response range the quantitative results of both method s are comparable. In conclusion, storage phosphor autoradiography is a faster technique for localizing and quantifying peptide receptors in tissue sections but slightly compromised in resolution when compared w ith film autoradiography.