Ghrelin is involved in voluntary anorexia in Atlantic salmon raised at elevated sea temperatures

Role of the GH-IGF-1 system in Atlantic salmon and rainbow trout postsmolts at elevated water temperature

“…In a recent study on adult 1.6-kg Atlantic salmon reared at 13, 15, 17 or 19°C, we showed that circulating plasma IGF-1 was not affected by temperature while growth and feed intake was reduced along with muscle igf1 at elevated temperatures . Similarly, adult 2.0-kg Atlantic salmon reared at elevated temperature (19°C) for 56 days, had reduced muscle igf1 mRNA when compared to the 14°C control group (Hevrøy et al, 2012). The same responses have been observed in juvenile southern flounder (Paralichthys lethostigma) reared at 23°C and 28°C with reduced food consumption, feed utilizations, growth, plasma IGF-1 and muscle igf1 mRNA at 28°C, which was regarded as a temperature above the optimum for growth .…”

“…In larger Atlantic salmon (1.6-2.0 kg) exposed to elevated temperatures at N18°C, it was previously observed that growth and feed intake increase to a plateau after which they decrease over time (Hevrøy et al, 2012. A reduction in feed intake and growth due to higher temperatures than the species' optimal range has also been seen in southern flounder , Paralichthys lethostigma and juvenile barramundi (Katersky and Carter, 2005), Lates calcarifer.…”

“…Global warming is therefore predicted to impact the future of salmon production locally. Thus, adult Atlantic salmon show reduced appetite and growth when exposed long term to 17 and 19°C seawater when compared with fish reared at 13 and 15°C (Hevrøy et al, 2012. We recently documented that 13°C is the optimal temperature for somatic growth in adult 1.6-kg Atlantic salmon, and that exposures to higher temperatures of 15, 17 or 19°C for 45 days all negatively affected growth .…”

Sequence, genomic organization and expression of ghrelin receptor in grass carp, Ctenopharyngodon idellus

“…In teleost, a goldfish that has four GHS-Ra that is divided into two types, 1a and 2a, and three of these four receptors (except 2a-2 receptor), were activated by goldfish ghrelin or GHS (Kaiya et al, 2010). Hevrøy et al (2012) have reported that lower circulating ghrelin during negative energy homeostasis induces down-regulation of GHSR1a-LR, neuropeptide Y, and anorexigenic factors at transcriptional levels in the hypothalamus, which over time lead to a voluntary anorexia development in adult salmon held at 19°C. The expression of the GH secretagogue receptors (sbGHSR-1a and sbGHSR-1b) was significantly increased in the hypothalamus of the food-deprived seabream (Zhang et al, 2008).…”

Differential metabolite levels in response to spawning-induced inappetence in Atlantic salmon Salmo salar

“…A common approach in veterinary and husbandry practice is to measure serum or plasma levels of molecules with already-known clinical significance in the specific species under study (Parry, 1961;Jeffries et al, 2011), or molecules with known significance in other model species that are expected to be important in the species under study (Dove et al, 2005(Dove et al, , 2010Hevroy et al, 2012). However, it is generally unknown what the serum levels of a given metabolite (e.g., glucose or free fatty acids) should be in normal versus different diseased or affected states for an arbitrarily-chosen species of fish.…”