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Desensitization and internalization of adenosine A1 receptors in rat brain by in vivo treatment with R-PIA: involvement of coated vesicles

1996; Elsevier BV; Volume: 1310; Issue: 1 Linguagem: Inglês

10.1016/0167-4889(95)00152-2

1879-2596

María Ángeles Ruiz, Juana María Sanz, Gloria González-Calero, Mercedes Fernández, Antonio Andrés, Aña Cubero, Manuel Ros,

Neuropeptides and Animal Physiology

Chronic treatment of rats with R-PIA 'in vivo' desensitized adenosine A1 receptor-mediated inhibition of adenylyl cyclase in brain plasma membranes and increased basal and forskolin-stimulated adenylyl cyclase. The adenosine A1 receptor agonist CHA (cyclohexyl adenosine) inhibited forskolin-stimulated adenylyl cyclase in synaptic plasma membranes from control rats but failed to do so in membranes isolated from rats treated with R-PIA. This loss of response was accompanied with a significant decrease in both, total number of adenosine A1 receptors and steady-state level of α-Gi in synaptic plasma membranes. An increase in the steady-state level of α-Gs in synaptic plasma membranes was also observed by R-PIA treatment. Concurrently, a significant increase of adenosine A1 receptors was observed in microsomes and coated vesicles. These results demonstrate adenosine A1 receptor desensitization in rat brain by 'in vivo' treatment with R-PIA and suggest a role for coated vesicles in the internalization of G-protein coupled receptors.