Research

Parecoxib is neuroprotective in spontaneously hypertensive rats after transient middle cerebral artery occlusion: a divided treatment response?

Jesper Kelsen^1,2,3 , Katrine Kjær⁴ , Gang Chen^3,5 , Michael Pedersen^3,5 , Lisbeth Røhl⁶ , Jørgen Frøkiær^1,3 , Søren Nielsen^1,7 , Jens R Nyengaard^3,8 and Lars Christian B Rønn⁴

¹  The Water and Salt Research Centre, University of Aarhus, DK-8000 Aarhus C, Denmark

²  Department of Neurosurgery NK, University Hospital of Aarhus, Noerrebrogade 44, DK-8000 Aarhus C, Denmark

³  Institute of Clinical Medicine, University Hospital of Aarhus, Brendstrupgaardsvej 100, DK-8200 Aarhus N, Denmark

⁴  NEUROSEARCH A/S, Pederstrupvej 93, DK-2750 Ballerup, Denmark

⁵  MR Research Centre, University Hospital of Aarhus, Brendstrupgaardsvej 100, DK-8200 Aarhus N, Denmark

⁶  Department of Radiology, University Hospital of Aarhus, Noerrebrogade 44, DK-8000 Aarhus C, Denmark

⁷  Institute of Anatomy, University of Aarhus, DK-8000 Aarhus C, Denmark

⁸  Stereology and EM Research Laboratory and MIND Center, University of Aarhus, DK-8000 Aarhus C, Denmark

author email corresponding author email

Journal of Neuroinflammation 2006, 3:31doi:10.1186/1742-2094-3-31

Published:	6 December 2006

Abstract

Background

Anti-inflammatory treatment affects ischemic damage and neurogenesis in rodent models of cerebral ischemia. We investigated the potential benefit of COX-2 inhibition with parecoxib in spontaneously hypertensive rats (SHRs) subjected to transient middle cerebral artery occlusion (tMCAo).

Methods

Sixty-four male SHRs were randomized to 90 min of intraluminal tMCAo or sham surgery. Parecoxib (10 mg/kg) or isotonic saline was administered intraperitoneally (IP) during the procedure, and twice daily thereafter. Nineteen animals were euthanized after 24 hours, and each hemisphere was examined for mRNA expression of pro-inflammatory cytokines and COX enzymes by quantitative RT-PCR. Twenty-three tMCAo animals were studied with diffusion and T₂ weighted MRI within the first 24 hours, and ten of the SHRs underwent follow-up MRI six days later. Thirty-three SHRs were given 5-bromo-2'-deoxy-uridine (BrdU) twice daily on Day 4 to 7 after tMCAo. Animals were euthanized on Day 8 and the brains were studied with free-floating immunohistochemistry for activated microglia (ED-1), hippocampal granule cell BrdU incorporation, and neuronal nuclei (NeuN). Infarct volume estimation was done using the 2D nucleator and Cavalieri principle on NeuN-stained coronal brain sections. The total number of BrdU⁺ cells in the dentate gyrus (DG) of the hippocampus was estimated using the optical fractionator.

Results

We found a significant reduction in infarct volume in parecoxib treated animals one week after tMCAo (p < 0.03). Cortical ADC values in the parecoxib group were markedly less increased on Day 8 (p < 0.01). Interestingly, the parecoxib treated rats were segregated into two subgroups, suggesting a responder vs. non-responder phenomenon. We found indications of mRNA up-regulation of IL-1β, IL-6, TNF-α and COX-2, whereas COX-1 remained unaffected. Hippocampal granule cell BrdU incorporation was not affected by parecoxib treatment. Presence of ED-1⁺ activated microglia in the hippocampus was related to an increase in BrdU uptake in the DG.

Conclusion

IP parecoxib administration during tMCAo was neuroprotective, as evidenced by a large reduction in mean infarct volume and a lower cortical ADC increment. Increased pro-inflammatory cytokine mRNA levels and hippocampal granule cell BrdU incorporation remained unaffected.