Appetite regulating factors in dourado, Salminus brasiliensis: cDNA cloning and effects of fasting and feeding on gene expression

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

“…Postprandial increases in CART brain expression have been shown in Senegalese sole (CART1a, CART 2a and CART4) (Bonacic et al, 2015), pacu (Volkoff et al, 2017), dourado (Volkoff et al, 2016), channel catfish (Peterson et al, 2012) but not in cod (Kehoe and Volkoff, 2007). …”

“…Indeed, in goldfish, hypothalamic orexin mRNA expression levels peak when fish are active prior to a scheduled meal (Hoskins and Volkoff, 2012) and in zebrafish, increased locomotor activity is associated with increased activity of hypothalamic orexin neurons (Naumann et al, 2010) and larvae overexpressing orexin are hyperactive (Woods et al, 2014). Similarly, orexin expression decreases post-feeding in Characiformes [cavefish (Wall and Volkoff, 2013), dourado ( Salminus brasiliensis ) (Volkoff et al, 2016) and pacu ( Piaractus mesopotamicus ) (Volkoff et al, 2017)] and is higher at mealtime in orange-spotted grouper (Yan et al, 2011) and tilapia (Chen et al, 2011) (Perciformes), as well as Atlantic cod (Gadiforme) (Xu and Volkoff, 2007). In cod, orexin levels are also higher during daylight hours, when animals are active (Hoskins and Volkoff, 2012).…”

“…Fasting increases orexin brain mRNA expression in Cypriniformes (goldfish Abbott and Volkoff, 2011 and zebrafish Yokobori et al, 2011), Characiformes (cavefish Wall and Volkoff, 2013, dourado Volkoff et al, 2016, pacu Volkoff et al, 2017, and red-bellied piranha Volkoff, 2014a), and Pleuronectiformes (winter flounder Buckley et al, 2010 and Barfin flounder Amiya et al, 2012). In the mouth-brooding Astatotilapia burtoni (Perciforme), brain orexin mRNA levels increase in non-feeding females carrying eggs (Grone et al, 2012).…”

“…Two CART isoforms have been identified in goldfish (Volkoff and Peter, 2001a) and common carp (Wan et al, 2012), and 4 in zebrafish (Akash et al, 2014) whereas, to date, only one form has been isolated for grass carp (Zhou et al, 2013; Liu et al, 2014), Characiformes [pirapitinga (serrasalmidae) (Volkoff, 2015a), pacu (serrasasalmidae) (Volkoff et al, 2017) and dourado (characidae) (Volkoff et al, 2016), red bellied piranha (serrasalmidae) (Volkoff, 2014a)], Salmoniformes [Atlantic salmon (Murashita et al, 2009a), rainbow trout (Figueiredo-Silva et al, 2012), Arctic charr (Striberny et al, 2015) and lake trout ( Salvelinus namaycush ) (Volkoff et al, 2007)], Siluriformes (channel catfish Kobayashi et al, 2008), Gadiformes (Atlantic cod Kehoe and Volkoff, 2007), Perciformes (cunner Babichuk and Volkoff, 2013), winter flounder (MacDonald and Volkoff, 2009a) and Atlantic halibut ( Hippoglossus hippoglossus ) (Gomes et al, 2015) (Pleuronectiformes), venomous toadfish Thalassophryne nattereri (Batrachoidiforme) (Magalhaes et al, 2006), rainbow smelt ( Osmerus mordax ) (Osmeriforme), pufferfishes ( Takifugu rubripes and Tetraodon nigroviridis , Tetraodontiforme) and stickleback Gasterosteus aculeatus (Gasterosteiforme) (cited in Murashita et al, 2009a). However, six forms of CART have been identified in the medaka (Beloniforme) (Murashita and Kurokawa, 2011) and seven forms in Senegalese sole Solea senegalensis (Pleuronectiforme), the highest number of CART genes reported to date in a vertebrate species (Bonacic et al, 2015).…”

“…However, in Arctic charr, CART hypothalamic expression is similar throughout the seasonal feeding cycles (Striberny et al, 2015) and fasting does not affect CART expression in either dourado (Volkoff et al, 2016), winter flounder (MacDonald and Volkoff, 2009a) or Atlantic halibut larvae (Gomes et al, 2015), and in lake trout, fish exposed to the pesticide tebufenozide and control fish have similar food intakes, despite higher CART mRNA brain expression levels in exposed fish (Volkoff et al, 2007). In winter skate, 2 weeks of fasting have no effects on brain CART expression (MacDonald and Volkoff, 2009b), suggesting that CART might not have a major feeding-regulating role in elasmobranchs.…”