2000, Number 1
Salud Mental 2000; 23 (1)
Otro sistema de transmisión opioide en el cerebro de los mamíferos. Endomorfinas y receptor opioide mu. Parte I
Leff P, Acevedo R, Valdés A, Martínez I, Morales A, Calva JC, Antón B
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ABSTRACTThe reception of signals from nociceptive stimuli is transmitted through primary afferents that project to the dorsal horn of the spinal cord where axons from these nerve fibers terminate and make synaptic contacts with neurons projecting to supraspinal regions of the brain and with local interneurons localized in the superficial layers of the dorsal horn. Spinal and supraspinal nociceptive transmission is controlled by the neuronal release of chemical transmitters that either activate and modulate as well the incoming nociceptive signals conveyed by a complex neuron network involving ascending and descending neural pathways that control the nociceptive transmission along the brain of mammals. Stimulation of the supraspinal regions of the brain is known to produce a prolonged and profound analgesia as well as a profound supression of activity of nociceptive pathways. Similarly, opiate alkaloids (morphine, etorphine) as well as several endogenous opioids (encephalins, β-endorphin) generate analgesic effects in rodents by interacting and activating different opioid receptors such as the mu and delta opioid receptor subtypes localizad in neurons that participate in the modulation of nociceptive transmission. New members of the brain endogenous opioid peptides superfamily have just been recently identified, isolated, characterized and named as endomorphin-1 and endomorphin-2. These peptides not only produce a profound and prolonged spinal and supraspinal analgesia, but they also seem to be the first natural opioid ligands to bind with high affinity and avidity to the mu opioid receptor subtype.