Perforant path lesioning induces sprouting of CA3-associated fibre systems in mouse hippocampal formation

Abstract

In comparison to the rat, the anatomy of the mouse hippocampus, and in particular the response to entorhinal cortex lesioning, is less well characterised. Here we studied the axonal sprouting response after lesioning of the entorhinodentate perforant path projection in young adult SJL/J and C57BL/6 mice. We found that lesioning led to translaminar sprouting of Timm stained regio inferior hippocampus (CA3)-associated fibre systems into the denervated termination zones of the CA3 and dentate gyrus, from the adjacent non-denervated stratum radiatum of CA3. Differences were seen in the Timm staining pattern of the two strains of mice, while the response to lesioning appeared similar albeit less pronounced than that observed in the rat. We also observed an intensified acetylcholine esterase staining reflective of cholinergic sprouting in the denervated perforant path termination zones, which was particularly prominent in areas with sprouting of Timm stained CA3-associated fibres. Finally, we showed that some of the sprouting fibres within the CA3 were myelinated, due to an increased density of silver impregnated myelinated fibres in this region after lesioning. These results show that the basic characteristics of the response to perforant path lesioning in mice are similar to those in the rat, but suggest that the magnitude of the response in the two species is different.

Toll-Like Receptor 2 Signaling in Response to Brain Injury: An Innate Bridge to Neuroinflammation

“…Increased intensity of AChE, found in cholinergic fibers, in the outer molecular layer of the dentate gyrus is associated with a postlesional plasticity response (Steward, 1992;Fagan and Gage, 1994;Drojdahl et al, 2002). At both 5 d (data not shown), before this response is easily detectable, and at 20 d after axotomy (Fig.…”

“…TLR2 signaling has been implicated in microglial responses such as are associated with repair via clearance of myelin debris in the denervated hippocampus (Bechmann and Nitsch, 2000;Drojdahl et al, 2002;Fenger et al, 2006). Phagocytes were shown to contain the TLR2 ligand peptidoglycan within multiple sclerosis lesions (Schrijver et al, 2001), and to use the TLR2/4 coreceptor CD14 to bind and phagocytose fibrillar ␤-amyloid (Fassbender et al, 2004;Liu et al, 2005), making CD14 and TLRs potential therapeutic targets in the injured or diseased CNS.…”

“…Enzymatic staining for acetylcholinesterase (AChE) was performed on perfusion-fixed material using a modification of the thiocholine method (Drojdahl et al, 2002). Degenerating fibers and terminals were visualized in parallel sections using Fluoro-Jade (Histo-Chem, Jefferson, AR) (Nguyen et al, 2001).…”

Original article Toll-like receptors as an innate immunity bridge to neuroinflammation in medulloblastoma

“…Results of the present study show that such pathogens may be also produced by dead medulloblastoma cells. The role of TLRs in pathology of the CNS was a subject of numerous studies, which documented the implication of TLR 2 signalling in glia responses associated with repair by the clearance of myelin debris [6,9,10].…”

Enhanced neuronal expression of major histocompatibility complex class I leads to aberrations in neurodevelopment and neurorepair

“…Perforant path lesions were performed as previously described (Drojdahl et al, 2002). Briefly, C57BL/6 or NSE-D b male mice (8–12 weeks old) were anesthetized and placed into a stereotaxic device.…”