Peptide Receptors Part I was published in 2000 (as volume 16 of the Handbook of Chemical Neuroanatomy series). This volume summarized current knowledge on the discrete anatomical distribution of ten families of neuropeptide receptors expressed in the mammalian CNS. Part II is its natural complement with chapters covering six additional families of neuropeptide receptors for ligands ranging from well known peptides such as the opioids and neurotensin to recently isolated ones like the orexins. As in the case of Part I, this volume integrates photomontages and maps of quantitative receptor autoradiography, in situ hybridization histochemistry and immunocytochemistry. Data derived from transgenic and knock-out animals are also summarized, helping to decipher the possible physiological and Pathophysiological role(s) of a given peptide family. Some chapters also review current knowledge on the profile of internalization of the neuropeptide-receptor complex, an area of intense research activities that should help to better understand mechanisms involved in desensitization and tachyphylaxis.