Ontogeny expression of ghrelin, neuropeptide Y and cholecystokinin in blunt snout bream, Megalobrama amblycephala

Abstract

Ghrelin, neuropeptide Y (NPY) and cholecystokinin (CCK) all have important roles in the regulation of feeding in fish and mammals. To better understand the role of the three peptides in appetite regulation in the early developmental stages of blunt snout bream (Megalobrama amblycephala), partial cDNA sequences of ghrelin, NPY and CCK genes were cloned. And then, real-time quantitative PCR and RT-PCR were used to detect and quantify the mRNA expressions of these genes from zygotes to larvae of 50 days after hatching (DAH). Ghrelin, NPY and CCK were all expressed throughout the embryonic and larval development stages, and the expression levels were higher in larval stages than in embryonic stages. Ghrelin and NPY mRNA expressions were upregulated at 1, 3, 5 DAH, while CCK mRNA expression was reduced significantly at 3 DAH. The mRNA expression levels of three genes in larvae varied significantly until 30 DAH. In adult fish, all three peptides were detected to be expressed in brain and several peripheral tissues. Ghrelin mRNA was mainly expressed in the intestine, whereas NPY and CCK mRNAs were mainly expressed in the brain. Taken together, these results indicate that ghrelin, NPY and CCK may have roles in early development and participate in the regulation of feeding of larvae in blunt snout bream and will be helpful for further investigation into feed intake regulation in adults of this species.

An immunohistochemical study on endocrine cells in the neuroendocrine system of the digestive tract of milkfish Chanos chanos (Forsskal, 1775)

“…In milkfish, as typical herbivorous fish, GAS-immunoreactive endocrine cells were founded in the anterior and middle regions of intestine, but were not detected in any regions of stomach. In fish, CCK peptide exists in the endocrine cells of digestive tract and within the central and peripheral nervous system (Ping et al 2014). The distribute characters of GAS-produced cells in the anterior region of intestine could be explicated by its functions of stimulation of gastrointestinal epithelium growth in milkfish.…”

“…In mammals, the regulation of food intake is achieved by the complex neuronal network in the hypothalamus through the integration of central and peripheral short-term appetite and satiety signals, as well as long-term energy balance signals. A series of signal molecules associated with regulation of feeding activity have been identified currently in the brain of fish, including orexigenic and anorexigenic neuropeptides (Xu & Volkoff 2009;Ping et al 2014). A series of signal molecules associated with regulation of feeding activity have been identified currently in the brain of fish, including orexigenic and anorexigenic neuropeptides (Xu & Volkoff 2009;Ping et al 2014).…”

Cloning, tissue distribution and effects of fasting on mRNA expression levels of leptin and ghrelin in red-bellied piranha (Pygocentrus nattereri)

“…Ghrelin mRNA has been observed in the brain of several fish, including goldfish (Unniappan et al, 2002), grass carp (Feng et al, 2013), and zebrafish (Amole and Unniappan, 2009), although no or very low ghrelin mRNA levels have been reported in brains of other fish, such as channel catfish , black sea bream Acanthopagrus schlegelii (Yeung et al, 2006) and seabass (Terova et al, 2008). High levels of ghrelin mRNA and protein levels in the stomach/intestine have also been shown in a number of fish, including goldfish (Unniappan et al, 2002), barfin flounder (Kaiya et al, 2013), Ya fish Zhou et al, 2014), grass carp (Feng et al, 2013), channel catfish , zebrafish (Amole and Unniappan, 2009), and blunt snout bream Megalobrama amblycephala (Ping et al, 2014). High GIT expression of ghrelin might suggest that this peptide is involved the peripheral regulation of gastrointestinal processes (digestion, absorption of nutrients) and feeding in red-bellied piranha.…”

The Neuroendocrine Regulation of Food Intake in Fish: A Review of Current Knowledge

“…The first direct evidence of the actions of CCK on feeding was provided by injections in goldfish (Himick and Peter, 1994), followed by cloning of goldfish CCK cDNA (Peyon et al, 1998) and the demonstration of periprandial variations in CCK mRNA expression levels (Peyon et al, 1999). Subsequently, a number of studies have characterized CCK in several fish, including other Cypriniformes (e.g., common carp Zhong et al, 2013; zebrafish Koven and Schulte, 2012; Tian et al, 2015; grass carp; blunt snout bream Ping et al, 2013; Ji et al, 2015), Characiformes (e.g., cavefish Wall and Volkoff, 2013, dourado Pereira et al, 2015; Volkoff et al, 2016, thin dogfish Oligosarcus hepsetus Vieira-Lopes et al, 2013, pirapitinga Volkoff, 2015a, red-bellied piranha Volkoff, 2014a, pacu Volkoff et al, 2017), Salmoniformes (e.g., Atlantic salmon Valen et al, 2011), Gadiformes (Atlantic cod Tillner et al, 2013), Perciformes [e.g., yellowtail (Furutani et al, 2013; Hosomi et al, 2014); Astatotilapia burtoni (Grone et al, 2012); cunner (Babichuk and Volkoff, 2013; Hayes and Volkoff, 2014); sea bass (Tillner et al, 2014); yellow croaker ( Larimichthys crocea ) (Cai et al, 2015); white sea bream, Diplodus sargus (Micale et al, 2012, 2014)], Pleuronectiformes (e.g., winter flounder (MacDonald and Volkoff, 2009a), Atlantic halibut Kamisaka et al, 2001, olive flounder Kurokawa et al, 2000) and Siluriformes (channel catfish Peterson et al, 2012). …”