Frachette M, Rennie K, Pappas BA (2007) Neonatal cholinergic lesion and environmental enrichment:behavior, neurogenesis and CA1 cytoarchitecture. Neuroscience 2007 Abstracts 691.9/M9. Society for Neuroscience, San Diego, CA.
Summary: The effects of neonatal cholinergic lesion and environmental enrichment on rat behaviour and hippocampal morphology were determined. Rats were injected with the immunotoxin 192 IgG- saporin (192S) on postnatal day 7, selectively lesioning forebrain cholinergic neurons as shown by their loss of acetylcholinesterase staining and p75NTR immunoreactive (IR) neurons. After weaning, the rats were placed in enriched or standard housing for 42 days. Enriched rats, regardless of whether or not they had received 192S, subsequently showed significantly enhanced performance on the working memory version of the Morris water maze. The lesion had no effect on spatial learning. However, the lesion significantly reduced doublecortin (DCX) IR cells in the dentate gyrus, indicating reduced hippocampal neurogenesis. Enrichment did not affect the number of DCX IR cells in lesioned rats whereas there was an apparent trend towards increased cells in non-lesioned rats. The number of DCX IR neurons in the enriched and impoverished lesion groups were identical and both were significantly less than the average for the enriched non-lesioned mean, suggesting that the lesioned rats were resistant to the effects of enrichment on neurogenesis. As shown by quantitative analysis of Golgi stained CA1 neurons, the cholinergic lesion affected CA1 cell morphology, reducing apical branches and total basal branch length. This was not prevented by enrichment. There were also a number of other effects selective for certain branches but these effects tended to be observed equally often in impoverished and enriched rats. In other words, the consequences of the cholinergic lesion were immune to the housing condition. Enrichment had several effects on hippocampal cytoarchitecture but these were selective for certain branch orders rather than global alterations. The most interesting consequence of enrichment, in terms of its implication for synapse density and information processing capability, was the increased spine density and spine number observed on some branches of the apical tree. This was evident only in the non-lesioned rats. Thus, neonatal cholinergic forebrain lesion reduces dentate gyrus neurogenesis, alters CA1 dendritic morphology but has no effect on spatial learning/memory. It also renders rats unresponsive to the effects of enrichment on dentate gyrus neurogenesis, CA1 dendritic spine morphology but not spatial learning/memory.
Related Products: 192-IgG-SAP (Cat. #IT-01)