1 research outputs found
Intrahippocampal pathways involved in learning/memory mechanisms are affected by intracerebral infusions of amyloid-beta25-35 peptide and hydrated fullerene C60 in rats
Primary memory impairments associated with increased level of amyloid-beta (Аβ) in the
brain have been shown to be linked, partially, with early pathological changes in the
entorhinal cortex (EC) which spread on the whole limbic system. While the hippocampus is
known to play a key role in learning and memory mechanisms, it is as yet unclear how its
structures are involved in the EC pathology. In this study, changes in memory and neuronal
morphology in male Wistar rats intrahippocampally injected with Аβ25–35 were correlated on
days 14 and 45 after the injection to reveal specific cognitive - structural associations. The
main focus was on the dentate gyrus (DG) and hippocampal areas of CA1 and CA3 because
of their involvement in afferent flows from EC to the hippocampus through tri-synaptic (EC
DG CA3 CA1) and/or mono-synaptic (EC CA1) pathways. Evident memory
impairments were observed at both time points after Аβ25–35 injection. However, on day 14,
populations of morphological intact neurons were decreased in CA3 and, drastically, in CA1,
and the DG supramedial bundle was significantly damaged. On day 45, this bundle largely
and СА1 neurons partially recovered, whereas CA3 neurons remained damaged. We
suggest that Аβ25–35 primarily affects the tri-synaptic pathway, destroying the granular cells in
the DG supramedial area and neurons in CA3 and, through the Schaffer collaterals, in CA1.
Intrahippocampal pretreatment with hydrated fullerene С60 allows the neurons and their
connections to survive the amyloidosis, thus supporting the memory mechanisms