DARPP-32 Expression in Rat Brain After an Inhibitory Avoidance Task |
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Authors: | Daniela V F Rosa Renan P Souza Bruno R Souza Melissa M Guimarães Daniel S Carneiro Samira S Valvassori Marcus V Gomez João Quevedo Marco A Romano-Silva |
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Institution: | Laboratório de Neurociência e Departamento de Saúde Mental, Faculdade de Medicina da Universidade Federal de Minas Gerais, Av Alfredo Balena, 190 sl 325, Belo Horizonte, 30130-100, MG, Brazil. |
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Abstract: | Step-down inhibitory avoidance (IA) is usually acquired in one single trial, which makes it ideal for studying processes initiated
by training, uncontaminated by prior or further trials, rehearsals, or retrievals. Biochemical events in the hippocampus related
to long-term memory (LTM) formation have been extensively studied in rats using a one trial step-down IA task. DARPP-32 (dopamine
and cAMP regulated phosphoprotein of Mr 32 kDa) is a cytosolic protein that is selectively enriched in medium spiny neurons in the neostriatum. It has been shown
that activation of DARPP-32 and the resultant inhibition of PP-1 activity is critical for the expression of two opposing forms
of brain synaptic plasticity, striatal LTD and LTP. Both forms of plasticity are also critically linked to the activation
of DA receptors. It has been shown with studies in DARPP-32 KO mice an important role of this protein in mediating the effects
of DA on long term changes in neuronal excitability and to our knowledge, no studies have examined the effect of IA task on
DARPP-32 expression. In order to demonstrate changes in the protein expression profile we analyzed DARPP-32 levels in the
striatum, prefrontal cortex (PFC), hippocampus and entorhinal cortex of Wistar rats after step-down IA learning. Our results
showed that IA induced changes on DARPP-32 expression in striatum and hippocampus. DARPP-32 expression changes corroborate
with changes in expression and phosphorylation of CREB, NMDA, AMPA after IA that has been reported. These changes suggest
that DARPP-32 might play a central role in the IA, as previously described as an integrator of the dopaminergic signal. |
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Keywords: | Inhibitory avoidance DARPP-32 LTD LTP Rat brain |
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