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Open Access Highly Accessed Research article

Differential neuropathic pain sensitivity and expression of spinal mediators in Lewis and Fischer 344 rats

Glenn-Marie Le Coz, Cathy Fiatte, Fernand Anton and Ulrike Hanesch*

Author Affiliations

Laboratory of Neurophysiology & Psychobiology, University of Luxembourg, 162a, avenue de la Faïencerie, Luxembourg, L-1511, Luxembourg

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BMC Neuroscience 2014, 15:35  doi:10.1186/1471-2202-15-35

Published: 28 February 2014

Abstract

Background

Altered hypothalamo-pituitary-adrenal (HPA) axis activity may be accompanied by a modulation of pain sensitivity. In a model of neuropathic pain (chronic constriction injury, CCI) we investigated the onset and maintenance of mechanical allodynia/hyperalgesia and the expression of biochemical mediators potentially involved in spinal cell modulation in two rat strains displaying either hypo- (Lewis-LEW) or hyper- (Fischer 344-FIS) reactivity of the HPA axis.

Results

Mechanical pain thresholds and plasmatic corticosterone levels were assessed before and during periods of 4 or 21 days following CCI surgery. At the end of the respective protocols, the mRNA expression of glial cell markers (GFAP and Iba1) and glutamate transporters (EAAT3 and EAAT2) were examined. We observed a correlation between the HPA axis reactivity and the pain behavior but not as commonly described in the literature; LEW rats seemed to be less sensitive than FIS from 4 to 14 days after the CCI surgery when looking at the mechanical allodynia/hyperalgesia. However, the biochemical spinal markers expression we observed is conflicting.

Conclusion

We did not find a specific causal relation between the pain behavior and the glial cell activation or the expression of the glutamate transporters, suggesting that the interaction between the HPA axis and the spinal activation pattern is more complex in a context of neuropathic pain.

Keywords:
HPA axis; Rat strains; Chronic constriction injury; Glutamate transporters; Glia cells; Spinal cord