Cerebral hypoxia ischemia increases toll-like receptor 2 and 4 expression in the hippocampus of neonatal rats

Aim of the study: Recent reports provide evidence that Toll-like receptors (TLRs) play a crucial role in cerebral ischemic injuries and neuronal cell death. The precise role of TLRs in mediating neuronal damage remains to be fully elucidated. In this study, we investigated the expression of TLR2 and TLR4 in the hippocampus of the neonatal rats. Materials and methods: Postnatal day 7 Sprague Dawley rats were used. The hypoxia ischemia brain injury models were made by ligature of the left common carotid artery and then inhalation of 8%O-2/92%N-2 for 2 h. TLR2 and TLR4 expression was assessed with immunohistochemical staining and Western blot assays at 3 d, 7 d, and 14 d after injury. Results: At the 3 d and 7 d time points, we found a significant increase in the number of TLR2 and TLR4 positive cells in the hippocampus of the HI group when compared with the sham group (P < 0.01). Western blot showed similar results. Conclusions: The study indicates that TLR2 and TLR4 are involved in the hypoxic ischemic injury of full-term neonatal brains. (C) 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.