Autoradiographic binding was studied on 20 µm coronal cryosections as described 34, using 5 nM [3H]DAMGO (48.9 Ci/mmol, NEN). Non-specific binding was determined from adjacent sections in the presence of the radioligand plus 10 µM naloxone. Radiolabeled, dried tissue sections and [3H]microscales (Amersham) were apposed to tritium-sensitive screens (Fujifilm imaging plates), and images were obtained using a Fujifilm BAS 5000 PhosphorImager.
