Two cholecystokinin receptor subtypes are identified in goldfish, being the CCKAR involved in the regulation of intestinal motility

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Tinoco Pérez, Ana Belén and Valenciano González, Ana Isabel and Gómez Boronat, Miguel and Blanco, A.M. and Nisembaum, Laura Gabriela and Pedro Ormeño, Nuria de and Delgado Saavedra, María Jesús (2015) Two cholecystokinin receptor subtypes are identified in goldfish, being the CCKAR involved in the regulation of intestinal motility. Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology, 187 . pp. 193-201. ISSN 1095-6433

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Official URL: http://www.sciencedirect.com/science/article/pii/S1095643315001622



Abstract

Cholecystokinin (CCK) plays a key role in the digestive physiology of vertebrates. However, very little is known about the role of CCK on intestinal functions in fish. The present study identifies two CCK receptor subtypes in a stomachless teleost, the goldfish (Carassius auratus), and investigates by using an in vitro system their involvement mediating the effects of the sulfated octapeptide of CCK (CCK-8S) on the motility of isolated proximal intestine. Partial-length mRNAs encoding two CCK receptor isoforms (CCKAR and CCKBR.I) were sequenced and the structural analysis showed that both receptors belong to the G-protein coupled receptor superfamily. Both gold- fish CCK receptor sequences were more closely related to zebrafish sequences, sharing the lowest similarities with cavefish and tilapia. The highest expression of goldfish CCKAR was observed along the whole intestine whereas the CCKBR gen was predominantly expressed in the hypothalamus, vagal lobe and posterior intestine. Application of CCK-8S to the organ bath evoked a concentration-dependent contractile response in intestine strips. The contractions were not blocked by either tetrodotoxin or atropine, suggesting that CCK-8S acts on the gut smooth muscle directly. Preincubations of intestine strips with devazepide and L365,260 (CCKAR and CCKBR receptor selective antagonists) showed that the CCK-8S-induced contraction could be partially mediated by the CCKAR receptor subtype, which is also the most abundant CCK receptor found in gastrointestinal tissues. In conclusion, two CCK receptors with a differential distribution pattern has been identified in goldfish, and the CCKAR subtype is mainly involved in the regulation of intestinal motility by the CCK-8S.


Item Type:Article
Uncontrolled Keywords:CCK receptors; Cholecystokinin; Fish; Intestinal motility; Organ bath; Phylogeny
Subjects:Medical sciences > Biology > Animal physiology
Medical sciences > Biology > Fishes
ID Code:42501
Deposited On:04 May 2017 08:40
Last Modified:11 May 2017 08:00

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