Behavioral pharmacology of neuropeptides related to melanocortins and the neurohypophyseal hormones

Neuropeptides are peptides which affect the nervous system. They are derive d from large precursor molecules. These are converted to neurohormones, neu ropeptides of the "first generation'', which can be further converted to ne uropeptides of the "second generation". This review is a brief survey of th e nervous system effects of neuropeptides derived from pro-opiomelanocortin (POMC) and the neurohypophyseal hormones. Processing of these molecules re sults in neuropeptides of the first and second generation which have simila r, different, more selective or even opposite effects. Among those are effe cts on learning and memory processes, grooming, stretching and yawning, soc ial, sexual and rewarded behavior, aging and nerve regeneration, thermoregu lation, pain, sensitivity to seizures, and cardiovascular control. Results of animal studies as well as those of clinical studies suggest that these n europeptides may be beneficial in aging, neuropathy, memory disturbances an d schizophrenia. Most of these nervous system effects in animal studies wer e found before receptors in the nervous system for the Various neuropeptide s were detected. G-protein-coupled receptors for the neuropeptides of the " first generation", i.e., melanocortin receptors, opioid receptors, and neur ohypophyseal hormone receptors have been found, in contrast to the receptor s for neuropeptides of the "second generation", although there are indicati ons that G-protein coupled receptors for these may be present in the brain. (C) 1999 Elsevier Science B.V. All rights reserved.