Neuropeptides are
peptides which affect the nervous system. They are derived from large precursor molecules. These are converted to
neurohormones,
neuropeptides of the "first generation", which can be further converted to
neuropeptides of the "second generation". This review is a brief survey of the nervous system effects of
neuropeptides derived from
pro-opiomelanocortin (
POMC) and the
neurohypophyseal hormones. Processing of these molecules results in
neuropeptides of the first and second generation which have similar, different, more selective or even opposite effects. Among those are effects on learning and memory processes, grooming, stretching and yawning, social, sexual and rewarded behavior, aging and nerve regeneration, thermoregulation,
pain, sensitivity to
seizures, and cardiovascular control. Results of animal studies as well as those of clinical studies suggest that these
neuropeptides may be beneficial in aging, neuropathy, memory disturbances and
schizophrenia. Most of these nervous system effects in animal studies were found before receptors in the nervous system for the various
neuropeptides were detected.
G-protein-coupled receptors for the
neuropeptides of the "first generation", i.e.,
melanocortin receptors,
opioid receptors, and neurohypophyseal
hormone receptors have been found, in contrast to the receptors for
neuropeptides of the "second generation", although there are indications that
G-protein coupled receptors for these may be present in the brain.