DEVELOPMENT OF A RAT MODEL FOR AMYLOID PATHOLOGY IN ALZHEIMER’S DISEASE USING RECOMBINANT AΒ1-42 PEPTIDE

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of β-amyloid (Aβ) plaques and neurofibrillary tangles. These changes lead to synaptic loss, neuronal death, and cognitive decline. A strong glial response, occurs around Aβ deposits, but the exact role of astrocytes is not fully understood. Experimental models that reproduce the key features of AD are important to study these cellular interactions under controlled conditions.

The aim of this work is to develop an experimental model of AD in rats through hippocampus (hc) injection of the Aβ1-42 peptide, in order to analyze astrocyte reactivity in brain regions close to and distant from amyloid plaques. For this, the gene coding for Aβ1-42 was cloned into the bacterial expression plasmid PetA30(+), adding a six-histidine (His-tag) sequence at the C-terminal end to allow purification by affinity chromatography.

The peptide was successfully expressed in E. coli BL21(DE3) and purified from inclusion bodies using a nickel affinity column. Afterwards, it was precipitated with ammonium sulfate and monomerized with HFIP. This solvent was removed with nitrogen, leaving a peptide film to be stored at -80 until use. The peptide film was solubilized in 20 mM NaOH and allowed to sediment. From the supernatant, a 1:3 mixture with PBS was prepared and 2 μL were injected into the rat hippocampus to induce the in vivo model. The sediment was resuspended in PBS and 5 μL were also injected in the rat hc.

In the next steps, we will perform structural and functional characterization of the purified peptide. This includes aggregation assays using Thioflavin T to measure fibril formation, and morphological analysis by atomic force microscopy. Once aggregation is confirmed, the model will be validated through histological analysis in hippocampus.

This model will help to explore the relationship between amyloid plaque formation and astrocyte response, providing useful tools to study the cellular mechanisms involved in AD pathophysiology.

This work was supported by the National Scientific and Technical Research Council (CONICET, PIP Nº 0317) and by the National University of La Plata (UNLP, M256).