TOPOGRAPHIC RELATIONSHIP OF NEUROTENSIN-CONTAINING AXON TERMINALS WITH CARDIAC AND NONCARDIAC PRINCIPAL GANGLION-CELLS IN THE STELLATE GANGLIA OF THE CAT

The pattern of association between neurotensin (NT)-immunoreactive (NT IR) preganglionic nerve terminals and cardiac and noncardiac neurons i n the stellate ganglion of the cat is analyzed, based on the finding o f an excitatory modulation effect of exogenous NT on cardiac functions . For this purpose, NT-containing terminals were labeled by immunohist ochemistry, and ganglion cells were detected by retrograde labeling of cardiac and vertebral nerves to identify cardiac and noncardiac neuro ns. To determine a possible regional localization of NTIR terminals an d ganglion cells, the ganglia were divided into four areas: caudal, do rsomedial, cranial, and ventromedial, related to the two major afferen t nerves (thoracic white rami 3 [T3WR] and 2 [T2WR]) and the two effer ent nerves (vertebral and cardiac). NTIR terminals were widespread in the complete ganglion tissue; they covered practically all the regions explored, although two clusters of high concentration of NTIR termina ls were detected in the cranial and caudal areas. By retrograde labeli ng it was found that cardiac cells were arranged around the exit of th e cardiac nerve and that the vertebral neurons were extended from the exit of the vertebral nerve to the entrance of T3WR. The finding of as sociation of NTIR terminals with cardiac neurons may account for the c ardioregulatory effect of NT; however, since the presence of NTIR term inals close to the noncardiac neurons is notorious, other regulatory f unctions of NT must be considered. (C) 1997 Wiley-Liss, Inc.