Galanin-like immunoreactive expression in the central nervous system of the toad

The distribution of galanin (GAL)-like immunoreactivity (-LI) was studied in the CNS of the toad (Bufo arenarum Hensel). Tissue sections were incubated with antibodies directed toward rat or porcine GAL and processed either for the avidin-biotin complex, or for the indirect immunofluorescence techniques. In the telencephalon GAL-immunoreactive (-IR) perikarya were observed in the ventral part of the striatum and in the septal accumbens nuclei. Immunopositive neurons were also observed in the medial amigdala with some intermingled cells between the fibers of the anterior commissure. Numerous GAL-IR perikarya were present along the rostrocaudal medial preoptic nucleus. Occasionally lightly immunoreactive cells were detected in the magnocellular region. The most numerous accumulation of GAL-IR cells was present in the ventral hypothalamus around the infundibular region, in the posterior tubercle and in the nucleus of the paraventricular organ. Immunostained cells were also present in the pretectal gray, solitary nucleus, gracil nucleus and in the spinal cord in the intermediate gray and in large motoneurons of the ventral horn. The widespread distribution found of GAL-LI suggests that GAL in the toad, as well as in mammalian species, may serve a variety of functions with a preponderant role in neuroendocrine processes. A role for GAL as a trophic factor in the brain of the toad is also suggested.