Colocalization of peptides and a catecholamine-synthesizing enzyme in intramural neurones of the newborn guinea-pig urinary bladder in culture

The patterns of colocalization of somatostatin (SOM), neuropeptide Y (NPY) and the catecholamine-synthesizing enzyme, dopamine beta-hydroxylase (DBH), were examined in intramural neurones in dissociated cell culture preparations from the detrusor muscle of the urinary bladder of the newborn guinea-pig using an elution-restaining immunocytochemical technique. Large numbers of the intramural neurones contained NPY-like (70-85% of the total neuronal population) and SOM-like (60-75%) immunoreactivities, in contrast to a small population (1-6%) of neurones containing immunoreactivity to DBH. Some neurones were immunoreactive to NPY (15-20%) and SOM (5-10%) alone, while 55-70% of the total neuronal population showed immunoreactivity to both NPY and SOM. NPY-like immunoreactive neuronal cell bodies that did not contain SOM were predominantly binucleate, whereas neuronal cell bodies immunoreactive to SOM alone were mainly mononucleate. Although not seen in every culture preparation, neuronal cell bodies containing both NPY-like and DBH-like immunoreactivities were also observed (less than 5% of the total neuronal population), and most, if not all, of these neuronal cell bodies were binucleate. SOM-like and DBH-like immunoreactivities were not seen in the same neuronal cell body throughout this study. These results show that intramural bladder neurones can be divided into distinct subpopulations based upon the coexistence of specific peptides and enzymes, and the possibility that they sustain local integrative and modulatory roles in bladder function is discussed.