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Compensatory cortical sprouting across the lifespan of the rat

Carnes B, DeLacalle S (2015) Compensatory cortical sprouting across the lifespan of the rat. Neuroscience 2015 Abstracts 391.10/C34. Society for Neuroscience, Chicago IL.

Summary: To investigate the plastic capacity of the cholinergic system in a partial animal model of Alzheimer’s disease, adult and aged rats received unilateral lesions of the horizontal diagonal band of Broca (HDB) using the cholinergic-specific toxin 192-IgG-saporin. The rats were sacrificed at 2, 4, 8, 12, or 24 weeks post lesion. Immuno- and histochemical techniques were used to quantify the effects of the lesion. Tissues were stained using an acetylcholinesterase technique. A 230µm by 200µm grid was used to indirectly measure the density of cholinergic fibers in the Entorhinal Cortex (EC). We compared our data to a young (3 month old) control group (Hartonian, 2005) in which the maximal loss of fiber density occurred by 8 weeks post-lesion and recovered to 75% of the intact contralateral EC by 12 weeks. All groups (young adult: 12-15; adult: 18; aged: 24-27 month old rats at the start of the experiment) exhibited a decrease in cortical fiber density after the lesion, which was more pronounced in the young adult group. All groups showed a recovery in fiber density to 60-80% of the intact side by 24 weeks post lesion. Interestingly, the loss occurred faster and more intense in the young adult group (to 25% of the intact side at 8 weeks post-lesion) than in the older ones (to 60% of the intact side by week 12 post lesion). Twenty four weeks after the lesion, the young adult group had recovered fiber density to 70%. The adult group also reached 70%, and the aged group reached 80% of the contralateral intact side. We conclude that following a cholinergic specific lesion, a compensatory mechanism is activated in the basal forebrain such that surviving neurons, projecting to the same target, are able to extend terminals and occupy the denervated area. It remains to be investigated whether the sprouts are able to establish proper synaptic connections and make a functional recovery.

Related Products: 192-IgG-SAP (Cat. #IT-01)

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