Present address: Department of Orthopedics, Institute of Surgical Sciences, Karolinska Institute at Karolinska Hospital, SE-17176 Stockholm, Sweden.
Interleukin-1β exacerbates and interleukin-1 receptor antagonist attenuates neuronal injury and microglial activation after excitotoxic damage in organotypic hippocampal slice cultures
Article first published online: 6 MAY 2005
European Journal of Neuroscience
Volume 21, Issue 9, pages 2347–2360, May 2005
How to Cite
Hailer, N. P., Vogt, C., Korf, H.-W. and Dehghani, F. (2005), Interleukin-1β exacerbates and interleukin-1 receptor antagonist attenuates neuronal injury and microglial activation after excitotoxic damage in organotypic hippocampal slice cultures. European Journal of Neuroscience, 21: 2347–2360. doi: 10.1111/j.1460-9568.2005.04067.x
- Issue published online: 23 MAY 2005
- Article first published online: 6 MAY 2005
- Received 15 July 2004, accepted 22 February 2005
- excitatory amino acid;
- propidium iodide;
The effects of interleukin (IL)-1β and IL-1 receptor antagonist (IL-1ra) on neurons and microglial cells were investigated in organotypic hippocampal slice cultures (OHSCs). OHSCs obtained from rats were excitotoxically lesioned after 6 days in vitro by application of N-methyl-d-aspartate (NMDA) and treated with IL-1β (6 ng/mL) or IL-1ra (40, 100 or 500 ng/mL) for up to 10 days. OHSCs were then analysed by bright field microscopy after hematoxylin staining and confocal laser scanning microscopy after labeling of damaged neurons with propidium iodide (PI) and fluorescent staining of microglial cells. The specificity of PI labeling of damaged neurons was validated by triple staining with neuronal and glial markers and it was observed that PI accumulated in damaged neurons only but not in microglial cells or astrocytes. Treatment of unlesioned OHSCs with IL-1β did not induce neuronal damage but caused an increase in the number of microglial cells. NMDA lesioning alone resulted in a massive increase in the number of microglial cells and degenerating neurons. Treatment of NMDA-lesioned OHSCs with IL-1β exacerbated neuronal cell death and further enhanced microglial cell numbers. Treatment of NMDA-lesioned cultures with IL-1ra significantly attenuated NMDA-induced neuronal damage and reduced the number of microglial cells, whereas application of IL-1ra in unlesioned OHSCs did not induce significant changes in either cell population. Our findings indicate that: (i) IL-1β directly affects the central nervous system and acts independently of infiltrating hematogenous cells; (ii) IL-1β induces microglial activation but is not neurotoxic per se; (iii) IL-1β enhances excitotoxic neuronal damage and microglial activation and (iv) IL-1ra, even when applied for only 4 h, reduces neuronal cell death and the number of microglial cells after excitotoxic damage.