PRESENCE OF C-FLANKING PEPTIDE OF NEUROPEPTIDE-Y (C-PON)-IMMUNOREACTIVE NEURONS IN THE OLFACTORY CORTEX OF THE HEDGEHOG (ERINACEUS-EUROPAEUS)

Although the presence of the neuropeptide C-terminal flanking peptide of neuropeptide Y, C-PON, has been described in the central nervous sy stem (CNS) of mammals, to date there is no information related with it s involvement in brain functions. An analysis of the location of C-PON in specific neuronal circuits of known anatomy and physiological acti on should provide light on its physiological role. The presence, distr ibution and morphology of C-PON-containing neurons in the olfactory co rtex of the hedgehog was studied by immunocytochemistry. Immunoreactiv e neurons to C-PON were widely distributed in the three layers of the olfactory cortex of this primitive mammal. These neurons were medium s ized and showed two or three immunostained, poorly branched, dendrites . In some positive neurons, a fine, beaded axon-like process was also immunostained. Although direct evidence of a physiological function of C-PON in the olfactory cortex of the hedgehog cannot be accurately st ated from our findings, the morphology of C-PON neurons and their dist ribution in the deep cortical layers, where the majority of pyramidal neurons are located, suggest that this neuropeptide may play a role in the intrinsic neuronal circuitry of the relatively well-developed hed gehog paleocortex. A regulatory vascular role of some peptide-immunore active neurons can be inferred since occasional C-PON-positive neurons have been located near blood vessels.