Regulation of vesicular acetylcholine transporter by the activation of excitatory amino acid receptors in the avian retina.
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 alpha-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.
Loureiro-dos-Santos
Nelson Enrique
NE
Instituto de Biofísica Carlos Chagas Filho-UFRJ, CCS, Ilha do Fundão, Rio de Janeiro, Rio de Janeiro, Brazil.
Prado
Marco Antonio M
MA
Reis
Ricardo Augusto de Melo
RA
Gardino
Patrícia F
PF
de Mello
Maria Christina F
MC
de Mello
Fernando G
FG
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism*; D002642:Chick Embryo; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000494:pharmacology; D026901:Membrane Transport Proteins; D009924:Organ Culture Techniques; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins
D000109:Acetylcholine; D002352:Carrier Proteins; D002795:Choline O-Acetyltransferase; D004791:Enzyme Inhibitors; D007608:Kainic Acid; D026901:Membrane Transport Proteins; D010880:Piperidines; D011493:Protein Kinase C; D018092:Kainic Acid Receptors; D013755:Tetradecanoylphorbol Acetate; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins; C006189:vesamicol