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Modulation of nociceptive transmission by pituitary adenylate cyclase activating polypeptide in the spinal cord of the mouse
- Source :
-
PAIN . Nov2002, Vol. 100 Issue 1/2, p27. 8p. - Publication Year :
- 2002
-
Abstract
- Superficial layers of the dorsal horn receive a dense plexus of nerve fibers immunoreactive to pituitary adenylate cyclase activating polypeptide (PACAP). In vivo experiments were conducted in the mice to evaluate the effects of PACAP-38, herein referred to as PACAP, PACAP receptor antagonist PACAP(6–38) and PACAP-antiserum on nociceptive behaviors induced by radiant heat, intrathecally administered N-methyl-d-aspartate (NMDA) or intraplantarly administered formalin. PACAP (0.05–0.5 μg) dose-dependently decreased the paw-withdrawal latencies induced by thermal stimulation and enhanced the aversive licking and biting behaviors induced by intrathecally injected NMDA. Pretreatment with the PACAP receptor antagonist PACAP(6–38) (0.5–2 μg) or PACAP-antiserum (1:500–2000 dilution) dose-dependently attenuated the second phase, but not the first phase, of nociceptive responses to formalin. Next, the effects of PACAP on NMDA- and kainate-induced currents evoked in single dorsal horn neurons were studied. Whole-cell patch recordings were made from superficial dorsal horn neurons of spinal cord slices from 14- to 20-day-old mice. PACAP at the concentrations of 100 and 200 nM, which caused no significant change of holding currents, increased NMDA-but not kainate-induced currents in superficial dorsal horn neurons. Our results suggest that exogenously applied PACAP sensitizes the dorsal horn neurons to formalin stimulation, and facilitates NMDA receptor-mediated nociceptive response. As a corollary, PACAP, which may be released from primary afferent fibers potentiates nociceptive transmission to the dorsal horn by interacting primarily with NMDA receptors. [Copyright &y& Elsevier]
- Subjects :
- *NERVE fibers
*ADENYLATE cyclase
Subjects
Details
- Language :
- English
- ISSN :
- 03043959
- Volume :
- 100
- Issue :
- 1/2
- Database :
- Academic Search Index
- Journal :
- PAIN
- Publication Type :
- Academic Journal
- Accession number :
- 7789496
- Full Text :
- https://doi.org/10.1016/S0304-3959(02)00207-5