Localization and distribution of CCK-8, NPY, Leu-ENK-, and Ghrelin- in the digestive tract of Prochilodus lineatus (Valenciennes, 1836).

Carlos E Barrios,Sebastián Sánchez,David R Hernández,Juan José Santinón,Hugo A Domitrovic

doi:10.1590/0001-3765202020181165

Abstract

This study describes the histological characteristics and distribution of gastrointestinal tract endocrine cells (ECs) of Prochilodus lineatus (detritivorous fish) using immunohistochemical procedures. The digestive tract of P. lineatus was divided into seven portions: stomach (cardial and pyloric), pyloric caeca, and intestine (anterior, glandular, middle and posterior). A pool of specific antisera against cholecystokinin (CCK-8), -neuropeptide Y (NPY), -ghrelin (Ghre) and -leu-enkephalin (Leu-ENK) to identify ECs were used. According to the morphological characteristics of ECs, two different types were identified and classified as open or closed-type. The number of ECs varied throughout the gastrointestinal tract, though a high abundance was found in the anterior intestine and pyloric caeca. A large number of ECs immunoreactive to CCK-8 and NPY were recorded in the anterior, glandular and middle intestine. ECs immunopositive to Leu-ENK were distributed in the stomach and pyloric caeca. For Ghre, immunopositive ECs were restricted to the glandular intestine. The results of the present study indicate that P. lineatus presents an ECs distribution pattern with species-specific particularities. However, CCK showed a distribution similar to that of omnivores, which is possibly related to local signaling functions in order to achieve the correct digestion of the various organisms found in the detritus.

Highlights

The digestive tract (DT) of fish exhibit a diversity of morphological and functional characteristics, varying from short and simple to long and complex (Olsson 2011), and it is fundamentally related to the different environments, diets, and developmental states of the individuals (Angelescu & Gneri 1949, Wilson & Castro 2010)
Open-type endocrine cells (ECs) exhibit an elongated shape and are wider in the zone occupied by Antibodies against Cholecystokinin Neuropeptide Y Leu-enkephalin Ghrelin
The occurrence and distribution of ECs was analyzed in the DT of several fish species, which showed considerable variation in morphology and physiology independent of trophic habit (Vigliano et al 2011, Pereira et al 2015, Lin et al 2017)

Summary

Introduction

The digestive tract (DT) of fish exhibit a diversity of morphological and functional characteristics, varying from short and simple to long and complex (Olsson 2011), and it is fundamentally related to the different environments, diets, and developmental states of the individuals (Angelescu & Gneri 1949, Wilson & Castro 2010). Several neuropeptide distribution patterns were observed according to different gastrointestinal tract morphologies and feeding habits, as observed in carnivores (Bosi et al 2004, Çinar et al 2006, Pereira et al 2015), omnivores (Kiliaan et al 1992, Pan et al 2000), and herbivores (Ku et al 2004, Lin et al 2017) Neuropeptides such as cholecystokinin (CCK), neuropeptide Y (NPY), leu-enkephalin (Leu-ENK), and ghrelin (Ghre) are synthesized by endocrine cells of the DT, and play a key role in nutritional homeostasis regulation. Ghrelin is known as an appetite-stimulating intestinal hormone and it is involved in multiple physiological functions, such as the regulation of food intake, growth, and reproduction (Kaiya et al 2008)

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