Species differences in the localization of neuropeptide FF receptors in rodent and lagomorph brain and spinal cord

Quantitative in vitro receptor autoradiography of [I-125] [D-Tyr(1),(NMe)Phe(3)] NPFF was used to study the regional distribution of neuropeptide FF receptors in rodent and lagomorph brain. In rat, mouse, rabbit, and Afghan pika [I-125] [D-Tyr(1),(NMe)Phe(3)] NPFF binding sites were enriched in the superficial layers of dorsal horn of the spinal cord and in parabrachial nucleus, central gray matter, hypothalamus, and reuniens thalamic nucleus. In other neuroanatomical regions, important species differences in NPFF receptor patterns are observed. In marked contrast, the brain and the spinal cord of the Octodon degus are devoid of NPFF receptors. The present study shows that in different species regional variations in brain NPFF receptor binding occur.