Poor evidence for insulin/insulin-like immunoreactivity in the CNS of lower vertebrates.

The localization of insulin/insulin-like immunoreactivity was studied in the brain and the pancreas of an amphibian (clawed frog [Xenopus laevis Daudin]) and in the CNS of two teleost fishes (bream [Abramis brama L.] and rudd [Scardinius erythrophthalmus L.] using the indirect immunofluorescence technique. With exception of cerebellar Purkinje cells no neuronal elements were found to contain insulin-like material. The frog pancreas was characterized by a strong immunofluorescence in cells producing the polypeptide.