RESUMEN
Galanin is a 29-amino acid neuropeptide found in rat spinal cord, autonomic ganglia and gastrointestinal tract, as well as in other areas of the nervous system in rats and other species. As part of an overall objective to determine if peptides contribute to target-specific control of visceral function, this study was designed to determine the percentages of populations of renal and splenic postganglionic neurons that contain galanin, and to determine if these neurons were likely to be adrenergic. Retrogradely transported fluorescent dyes were placed on renal and splenic nerves in male Wistar rats anaesthetized with sodium pento-barbital. Four days post-operatively, rats were perfused transcardially with fixative, and T12-L1 thoracolumbar chain ganglia, splanchnic ganglia and the solar plexus were removed. Immunocytochemical methods were then used to determine the proportions of the retrogradely labelled renal and splenic neurons containing galanin-like immunoreactivity and dopamine beta hydroxylase-like immunoreactivity. In seven rats, 24 +/- 3% of 2838 renal neurons were found to contain galanin-like immunoreactivity; in six rats, 32 +/- 5% of 5102 splenic neurons were found to contain galanin-like immunoreactivity. These proportions of the two populations were not significantly different from one another. In three rats, 94 +/- 2% of 684 renal neurons were found to contain dopamine beta hydroxylase-like immunoreactivity, and 95 +/- 2% of 2597 splenic neurons in three rats also showed dopamine beta hydroxylase-like immunoreactivity. These experiments indicate that subpopulations of both renal and splenic postganglionic sympathetic neurons contain the neuropeptide galanin and that these neurons are likely to be adrenergic in function. These findings suggest a role for galanin in control of the kidney and the spleen by the sympathetic nervous system.