Insulin signaling effects on 2-arachidonoylglycerol hydrolysis in synaptic terminals exposed to amyloid beta oligomers

PASCUAL, A.C.; PASQUARÉ, S.J.; GIUSTO, N.M.; FERNANDEZ, V.J.

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

2-arachidonoylglycerol (2-AG) behaves as a neuroprotective agent in Alzheimer?s disease (AD). Aβ oligomers (OAβ) are responsible for the synaptic dysfunction observed in AD and were shown to disrupt the synaptosomal membrane and to diminish 2-AG availability. Insulin (Ins) is involved in synaptic plasticity and its signaling was shown to be downregulated in AD. OAβ can bind to insulin receptor (IR) and can, therefore, be internalized into neurons, while Ins prevents this binding and thus its neurotoxicity. Here, we aimed to study Ins preincubation effects on 2-AG hydrolysis in cerebral cortex synaptosomes (Syn) exposed to OAβ. To this end, Syn were isolated by differential centrifugation, purified in ficoll gradients, and preincubated with 10 µM LY294002 (phosphatidylinositol-3-kinase -PI3K- inhibitor) or 100 µM genistein (tyrosine kinase -TK- Inhibitor) for 10 min, and subsequently incubated with 0.2 mM vanadate (protein-tyrosine phosphatase inhibitor), 100 nM Ins, or 0.2 mM vanadate plus 100 nM Ins, for 30 min. Syn were then incubated for 10 min with or without 0.1 µM OAβ, and for 20 min with [3H]monoacylglycerol, to assay 2-AG hydrolysis. It was observed that Ins and vanadate -either separately or coincubated- decreased 2-AG hydrolysis (p0.05). On the other hand, in the presence of OAβ, while Ins and vanadate failed to alter 2-AG hydrolysis (p>0.05), LY increased this activity (p