AUTORADIOGRAPHIC DISTRIBUTION OF NEUROPEPTIDE TYROSINE BINDING-SITES IN THE BRAIN OF THE AFRICAN LUNGFISH, PROTOPTERUS ANNECTENS

The distribution of neuropeptide tyrosine (NPY) binding sites in the b rain of the African lungfish, Protopterus annectens, was studied by au toradiography using radioiodinated NPY as a tracer. The highest concen trations of binding sites were found in the dorsal and intermediate pa rts of the medial pallium, the dorsal pallium, and in the medial and l ateral subpallium. These observations, together with the finding of a moderate density of binding sites in the olfactory bulbs, suggest that NPY may be involved in the processing of olfactory information and/or neuromodulation of limbic activities. High densities of binding sites were also found in several rhombencephalic nuclei, including the nucl eus fascicoli solitarii, the nucleus motorius nervi vagi, the spinal m otor column and all components of the reticular formation, indicating that NPY may play a role in the regulation of neurovegetative function s. Concurrently, the presence of high concentrations of binding sites in the hypophysis suggests that, in the lungfish, NPY may exert a dire ct control of pituitary hormone secretion. (C) 1998 Elsevier Science I reland Ltd. All rights reserved.