Oxytocin, but not vassopressin, modulates nociceptive responses in dorsal horn neurons.
Oxytocin (OT) and vasopressin (VP) are synthesized and secreted by the paraventricular hypothalamic nucleus (PVN), and both peptides have been implicated in the pain modulatory system. In the spinal cord, activation of OT-containing axons modulates nociceptive neuronal responses in dorsal horn neurons; however, it is not known whether the direct VPergic descending projection participates. Here, we show that both PVN electrical stimulation and topical application of OT in the vicinity of identified and recorded dorsal horn WDR selectively inhibit Adelta and C-fiber responses. In contrast, the topical administration of VP on the same neurons did not affect the nociceptive responses. In addition, the reduction in nociceptive responses caused by PVN stimulation or OT administration was blocked with a selective OT antagonist. The results suggest that the VP descending projection does not modulate the antinociceptive effects mediated by the PVN on dorsal horn neurons; instead, it is the hypothalamic-spinal OT projection that regulates nociceptive information.
Rojas-Piloni
Gerardo
G
Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Boulevard Juriquilla 3001, Querétaro 76230 , Mexico. piloni@unam.mx
Gerardo
Rojas-Piloni
RP
Mejía-Rodríguez
Rosalinda
R
Rosalinda
Mejía-Rodríguez
MR
Martínez-Lorenzana
Guadalupe
G
Guadalupe
Martínez-Lorenzana
ML
Condés-Lara
Miguel
M
Miguel
Condés-Lara
CL
D000200:Action Potentials; D000818:Animals; D004558:Electric Stimulation; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology; D020671:Posterior Horn Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014667:Vasopressins / Q000494:pharmacology / Q000502:physiology*
D014667:Vasopressins; D010121:Oxytocin