Nociceptive behaviour upon modulation of mu-opioid receptors in the ventrobasal complex of the thalamus of rats

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Daniel Pozza (Author) FMUP; Catarina Potes (Author) Other; Patricia Barroso (Author) Other; Azevedo L (Author) FMUP; Castro Lopes J.M. (Author) FMUP; Fani Neto (Author) FMUP

Journal

Title: Pain

Vol. 148 No. 3

Pages: 492-502

ISSN: 0304-3959

Publisher: Wolters Kluwer Health

Indexing

ISI Web of Knowledge - 6 Citations

ISI Web of Science

Scopus - 7 Citations

Pubmed / Medline

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences

Other information

Authenticus ID: P-003-8YQ

DOI: 10.1016/j.pain.2009.12.013

Abstract (EN): The role of mu-opioid receptors (MORs) in the inflammatory pain processing mechanisms within the ventrobasal complex of the thalamus (VB) is not well understood. This study investigated the effect of modulating MOR activity upon nociception, by stereotaxically injecting specific ligands in the VB. Nociceptive behaviour was evaluated in two established animal models of inflammatory pain, by using the formalin (acute and tonic pain) and the ankle-bend (chronic monoarthritic pain) tests. Control (saline intra-VB injection) formalin-injected rats showed acute and tonic pain-related behaviours. In contrast, intrathalamic administration of [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin acetate (DAMGO), a MOR-specific agonist, induced a statistically significant decrease of all tonic phase pain-related behaviours assessed until 30-35 min after formalin hind paw injection. In the acute phase only the number of paw-jerks was affected. In monoarthritic rats, there was a noticeable antinociceptive effect with approximately 40 min of duration, as denoted by the reduced ankle-bend scores observed after DAMGO injection. Intra-VB injection of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP), a specific MOR antagonist, or of CTOP followed, 10 min after, by DAMGO had no effects in either formalin or ankle-bend tests. Data show that DAMGO-induced MOR activation in the VB has an antinociceptive effect in the formalin test as well as in chronic pain observed in MA rats, suggesting an important and specific role for MORs in the VB processing of inflammatory pain.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11