Regulation of vesicular acetylcholine transporter by the activation of excitatory amino acid receptors in the avian retina |
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Authors: | Loureiro-dos-Santos Nelson Enrique Prado Marco Antonio M Reis Ricardo Augusto de Melo Gardino Patrícia F de Mello Maria Christina F de Mello Fernando G |
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Institution: | (1) Instituto de Biofísica Carlos Chagas Filho-UFRJ, CCS, Ilha do Fundão, Rio de Janeiro, Rio de Janeiro, Brazil;(2) Laboratório de Neurofarmacologia, Departamento de Farmacologia, ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil |
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Abstract: | 1. Previous studies have shown that phorbol esters induce protein kinase C (PKC) mediated phosphorylation of the vesicular acetylcholine transporter (VAChT) and change its interaction with vesamicol. However, it is not clear whether physiological activation of receptors coupled to PKC activation can alter VAChT behavior.2. Here we tested whether activation of kaianate (KA) receptors alters VAChT. Several studies suggest that the cholinergic amacrine cells display KA/AMPA receptors that mediate excitatory input to these neurons. In addition, KA in the chicken retina can generate intracellular messengers with the potential to regulate cellular functions.3. In cultured chicken retina (E8C11) KA reduced vesamicol binding to VAChT by 53%. This effect was potentiated by okadaic acid, a protein phosphatase inhibitor, and was totally prevented by BIM, a PKC inhibitor.4. Phorbol myristate acetate (PMA), but not -PMA, reduced in more than 85% the number of L-3H]-vesamicol-specific binding sites in chicken retina, confirming that activation of PKC can influence vesamicol binding to chicken VAChT.5. The data show that activation of glutamatergic receptors reduces 3H]-vesamicol binding sites (VAChT) likely by activating PKC and increasing the phosphorylation of the ACh carrier. |
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Keywords: | VAChT excitatory amino acids PKC DAG |
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