The function of alpha-2-adrenoceptors in the rat locus coeruleus is preserved in the chronic constriction injury model of neuropathic pain

• Type: Article in International Scientific Journal
• Date: 2012

Authors

Alba Delgado, C (Author) Other; Borges, G (Author) Other; Sanchez Blazquez, P (Author) Other; Ortega, JE (Author) Other; Horrillo, I (Author) Other; Mico, JA (Author) Other; Meana, JJ (Author) Other; Neto F.L. (Author) FMUP; Berrocoso, E (Author) Other

Journal

Title: Psychopharmacology

Vol. 221

Pages: 53-65

ISSN: 0033-3158

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 37 Citations

Scopus - 39 Citations

Other information

Authenticus ID: P-002-AVQ

DOI: 10.1007/s00213-011-2542-7

Abstract (EN): Peripheral neuropathic pain is a chronic condition that may produce plastic changes in several brain regions. The noradrenergic locus coeruleus (LC) is a crucial component of ascending and descending pain pathways, both of which are frequently compromised after nerve injury. The objective of the study was to examine whether chronic constriction injury (CCI), a model of neuropathic pain, alters noradrenergic activity in the rat LC. Activity in the LC was assessed by electrophysiology and microdialysis, while protein expression was monitored in western blots and by immunohistochemistry. The pain threshold had dropped in injured rats 7 days after inducing neuropathy. While alpha-2-adrenoceptors mediate activity in the LC and in its terminal areas, no alterations in either spontaneous neuronal activity or extracellular noradrenaline levels were observed following CCI. Moreover, alpha-2-adrenoceptor activity in the LC of CCI rats remained unchanged after systemic administration of UK14,304, RX821002 or desipramine. Accordingly, extracellular noradrenaline levels in the LC were similar in CCI and control animals following local administration of clonidine or RX821002. In addition, there were no changes in the expression of the alpha-2-adrenoceptors, G alpha i/z subunits or the regulators of G-protein signaling. However, pERK1/2 (phosphorylated extracellular signal-regulated kinases 1/2) expression augmented in the spinal cord, paragigantocellularis nucleus (PGi) and dorsal raphe nucleus (DRN) following CCI. Neuropathic pain is not accompanied by modifications in tonic LC activity after the onset of pain. This may indicate that the signals from the PGi and DRN, the excitatory and inhibitory afferents of the LC, cancel one another out.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13