RESUMO
Soluble oligomers of the amyloid-ß peptide (AßOs) accumulate in the brains of Alzheimer disease (AD) patients and are implicated in synapse failure and early memory loss in AD. AßOs have been shown to impact synapse function by inhibiting long term potentiation, facilitating the induction of long term depression and inducing internalization of both AMPA and NMDA glutamate receptors, critical players in plasticity mechanisms. Because activation of dopamine D1/D5 receptors plays important roles in memory circuits by increasing the insertion of AMPA and NMDA receptors at synapses, we hypothesized that selective activation of D1/D5 receptors could protect synapses from the deleterious action of AßOs. We show that SKF81297, a selective D1/D5 receptor agonist, prevented the reduction in surface levels of AMPA and NMDA receptors induced by AßOs in hippocampal neurons in culture. Protection by SKF81297 was abrogated by the specific D1/D5 antagonist, SCH23390. Levels of AMPA receptor subunit GluR1 phosphorylated at Ser(845), which regulates AMPA receptor association with the plasma membrane, were reduced in a calcineurin-dependent manner in the presence of AßOs, and treatment with SKF81297 prevented this reduction. Establishing the functional relevance of these findings, SKF81297 blocked the impairment of long term potentiation induced by AßOs in hippocampal slices. Results suggest that D1/D5 receptors may be relevant targets for development of novel pharmacological approaches to prevent synapse failure in AD.
