Role of Pituitary Adenylate Cyclase Activating Polypeptide in nociceptive processes: behavioural and immunohistochemical studies
Katalin
Sándor1*,
Viktoria
Kormos1,
András
Imreh1,
Bálint
Botz1,
Kata
Bölcskei2, 3,
Balázs
Gaszner4,
Dóra
Reglodi4,
János
Szolcsányi1,
Norihito
Shintani5,
Hitoshi
Hashimoto5,
Akemichi
Baba5 and
Zsuzsanna
Helyes1
-
1
University of Pecs, Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Hungary
-
2
University of Pecs, Analgesic Research Laboratory, Hungary
-
3
Gedeon Richter Ltd., Hungary
-
4
University of Pecs, Department of Anatomy, Faculty of Medicine, Hungary
-
5
Osaka University, Graduate School of Pharmaceutical Sciences, Japan
Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) and its receptors have been shown in the spinal dorsal horn, dorsal root ganglia and sensory nerve terminals. Data concerning the role of PACAP in central pain transmission are controversial, we have recently published its divergent peripheral effects on nociceptive processes.
The aim of this study was to investigate acute somatic and visceral nocifensive behaviours, partial sciatic nerve ligation-evoked chronic neuropathic, and resiniferatoxin-induced inflammatory thermal/mechanical hyperalgesia in PACAP deficient (PACAP-/-) mice to elucidate its overall function in pain transmission. Neuronal activation was investigated with c-Fos immunohistochemistry.
Paw lickings in the early and late phases of the formalin test were markedly reduced in PACAP-/- mice. Acute visceral chemonociception was also significantly attenuated in PACAP-/- animals. In both models, the excitatory role of PACAP was supported by markedly greater c-Fos expression in the periaqueductal grey and the somatosensory cortex. In PACAP-deficient animals neuropathic mechanical hyperalgesia was absent, while c-Fos immunopositivity 20 days after the operation was significantly higher. In this chronic model, these neurons are likely to indicate the activation of secondary inhibitory pathways. Resiniferatoxin-evoked mechanical hyperalgesia involving both peripheral and central processes was decreased, but thermal allodynia mediated by only peripheral mechanisms was increased in PACAP-/- mice.
These data clearly demonstrate an overall excitatory role of PACAP in pain transmission originating from both exteroceptive and interoceptive areas, it is also involved in central sensitization. This can be explained by the signal transduction mechanisms of its identified receptors. In contrast, it is an inhibitory mediator at the level of the peripheral sensory nerve endings and decreases their sensitization to heat with presently unknown mechanisms.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory and motor systems
Citation:
Sándor
K,
Kormos
V,
Imreh
A,
Botz
B,
Bölcskei
K,
Gaszner
B,
Reglodi
D,
Szolcsányi
J,
Shintani
N,
Hashimoto
H,
Baba
A and
Helyes
Z
(2010). Role of Pituitary Adenylate Cyclase Activating Polypeptide in nociceptive processes: behavioural and immunohistochemical studies.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00266
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Received:
06 May 2010;
Published Online:
06 May 2010.
*
Correspondence:
Katalin Sándor, University of Pecs, Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Pecs, Hungary, sandorkatalin@gmail.com