CCKa and CCKb receptor subtypes both mediate the effects of CCK-8 on myenteric neurones in the guinea-pig ileum

• Published in: Journal of the autonomic nervous system 1997, Vol.67
• Main Authors: Schutte, I.W.M, Akkermans, L.M.A, Kroese, A.B.A
• Format: Article
• Subjects: Fysiologie van Mens en Dier; Human and Animal Physiology; Leerstoelgroep Fysiologie van mens en dier; WIAS
• ISSN: 0165-1838; 1872-7476

The effects of cholecystokinin (CCK-8) on myenteric S neurons were investigated by intracellular recording techniques, with the aim to determine the CCK receptor subtypes involved. CCK-8 (1-1000 nM) evoked concentration-dependent long-lasting excitatory responses in 45 of 54 neurons. CCK receptor antagonists were applied to 15 neurons in which CCK-8 evoked an excitatory response. In 5 of these neurons, application of the CCK(A) antagonist L-364,718 (100-500 nM) antagonized the action of CCK-8 and the CCK(B) antagonist L-365,260 (500 nM) had no effect. L-365,260 (100-500 nM) antagonized the CCK-8 induced response in 5 neurons, on which L-364,718 had no effect. In the Ether 5 neurons each antagonist (500 nM) partly inhibited the CCK-8 evoked excitation and application of both antagonists (500 nM) caused a complete blockade of the response to CCK-8. The selective CCK(B) receptor agonist CCK-8NS had similar excitatory effects as CCK-8, but only on the neurons in which CCK-8 evoked effects were antagonized by L-365,260. The results demonstrate that the excitatory effects of CCK-8 are mediated by both CCK(A) and CCK(B) receptor subtypes. Further, the results indicate that some neurons possess exclusively the CCK(A) or the CCK(B) receptor subtype, but others possess both subtypes.