Localization and function of adenosine receptor subtypes at the longitudinal muscle - Myenteric plexus of the rat ileum

• Tipo: Artigo em Revista Científica Internacional
• Data: 2011

Autores

Vieira, C (Autor) Outra; Fátima Ferreirinha (Autor) ICBAS; Silva, I (Autor) Outra; Margarida Araújo (Autor) ICBAS; Paulo Correia de Sá (Autor) ICBAS

Revista

Título: Neurochemistry International

Vol. 59

Páginas: 1043-1055

ISSN: 0197-0186

Editora: Elsevier

Indexação

ISI Web of Knowledge - 14 Citações

Scopus - 15 Citações

Outras Informações

ID Authenticus: P-002-J29

DOI: 10.1016/j.neuint.2011.08.016

Abstract (EN): Adenosine plays a dual role on acetylcholine (ACh) release from myenteric motoneurons via the activation of high-affinity inhibitory A(1) and facilitatory A(2A) receptors. The therapeutic potential of adenosine-related compounds for controlling intestinal motility and inflammation, prompted us to investigate further the role of low-affinity adenosine receptors, A(2B) and A(3), on electrically-evoked (5 Hz, 200 pulses) [(3)H]ACh release from myenteric neurons. Immunolocalization studies showed that A(2B) receptors exhibit a pattern of distribution similar to the glial cell marker, GFAP. Regarding AI and A(3) receptors, they are mainly distributed to cell bodies of ganglionic myenteric neurons, whereas A(2A) receptors are localized predominantly on cholinergic nerve terminals. Using selective antagonists (DPCPX, ZM241385 and MRS1191), data indicate that modulation of evoked [(3)H]ACh release is balanced through tonic activation of inhibitory (A(1)) and facilitatory (A(2A) and A(3)) receptors by endogenous adenosine. The selective A(2B) receptor antagonist. PSB603, alone was devoid of effect and failed to modify the inhibitory effect of NECA. The A(3) receptor agonist, 2-Cl-IB MECA (1-10 nM), concentration-dependently increased the release of [(3)H]ACh. The effect of 2-Cl-IB MECA was attenuated by MRS1191 and by ZM241385, which selectively block respectively A(3) and A(2A) receptors. In contrast to 2-Cl-IB MECA, activation of A(2A) receptors with CGS21680C attenuated nicotinic facilitation of ACh release induced by focal depolarization of myenteric nerve terminals in the presence of tetrodotoxin. Tandem localization of excitatory A(3) and A(2A) receptors along myenteric neurons explains why stimulation of A(3) receptors (with 2-Cl-IB MECA) on nerve cell bodies acts cooperatively with prejunctional facilitatory A(2A) receptors to up-regulate acetylcholine release. The results presented herein consolidate and expand the current understanding of adenosine receptor distribution and function in the myenteric plexus of the rat ileum, and should be taken into consideration for data interpretation regarding the pathophysiological implications of adenosine on intestinal motility disorders.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 13