[Pain and its main transmitters].
The pain message originates peripherally from a great variety of substances either released from preformed stores or extemporaneously synthetized. They stimulate or sensitize nociceptors which are associated with the peripheral endings of sensitive protoneurones. Their central endings release many types of transmitters in the dorsal horn of medulla (substance P, NO, CGRP.). At this level their release, triggered by the firing rate, is modulated by the stimulation of various presynaptic receptors operated by transmitters produced by either interneurones (enkephalins) or medullar descending neurons (dopamine, norepinephrine, serotonine). These modulations correspond to the so-called gate control. The sensitive consecutive neurones which climb towards various brain areas are submitted to contradictory influences. Several of them enhance the pain perception (nociceptin, cholecystokinin, neuropeptide FF.) whereas several other reduce it (endorphines, neurotensin, neuromedin N, anandamide.).
Costentin
J
J
Unité de Neuropsychopharmacologie Expérimentale, ESA 6036 CNRS, Institut Fédératif de Recherches Multidisciplinaires sur les Peptides=IFR 23, Faculté de Médecine et Pharmacie, 22, bd Gambetta, F 76000 Rouen.
D000818:Animals; D004723:Endorphins / Q000502:physiology; D006801:Humans; D009479:Neuropeptides / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*
D004723:Endorphins; D009479:Neuropeptides; D018377:Neurotransmitter Agents