Developmental forebrain cholinergic lesion and environmental enrichment: behaviour, XXXX cytoarchitecture and neurogenesis.

@entity131 @entity1249 @entity75 @entity409 @entity2343 @entity35
Intraventricular injections of 192 IgG saporin in 7-day-old @entity35 severely reduced @entity131 as reflected by both decreased acetylcholinesterase staining and immunoreactivity for the p75 neurotrophin receptor. It was determined if this altered the effects of environmental enrichment on spatial learning, hippocampal @entity1249 cell cytoarchitecture as reflected by the Golgi stain, and neurogenesis in the dentate gyrus as indicated by doublecortin immunoreactivity. At weaning, lesioned and control @entity35 were either group housed in large, environmentally enriched cages or housed two per standard cage for 42 days. When subsequently assessed with a working-memory spatial navigation task, both lesioned and control @entity35 showed enhanced learning as a result of enrichment. Quantitative analysis of Golgi stained sections indicated that enrichment did not affect @entity1249 @entity2343 or dendritic spine density. However, the lesion reduced the number of apical branches, spine density on intermediate to distal apical dendrites, and the length of basal branches. It also reduced the number of doublecortin immunoreactive neurons in the dentate gyrus and appeared to prevent their increase due to environmental enrichment. It is concluded that developmental cholinergic lesioning does not attenuate neurobehavioral plasticity, at least as reflected by the behavioral consequences of enrichment. It does, however, attenuate neurogenesis in the dentate gyrus, like adult-inflicted cholinergic lesions. As previously found for cortical neurons, it also reduces @entity1249 pyramidal cell dendritic complexity and spine density in adulthood. The results have implications for the loss of synapses that occurs in both developmental and aging-related @entity75 involving @entity409 .
