Differential expression of two GH receptor mRNAs following temperature change in rainbow trout (Oncorhynchus mykiss)

Abstract

The recent genome duplication in salmonids has led to the presence of two GH receptors (GHRs). As temperature is a determining factor in fish growth, this study aims to determine whether the growth-promoting effect of temperature may be related to a change in GHR gene expression in embryo and juvenile rainbow trout. During embryonic development, using real-time PCR, we showed that high temperatures (12 vs 4 8C) increased the amounts of GHR1 transcript up to the hatching stage. By contrast, whatever the stage examined, the levels of GHR2 mRNA were unaffected by the incubation temperature. Nevertheless, incubating eggs with GH led to an enhanced embryo weight only after hatching, suggesting that GHR was not able to mediate the growth-promoting effect of GH before hatching. For juveniles, the GH-binding capacities of fish liver reared at 8, 12 or 16 8C revealed that high temperatures led to a lower GH binding. To better understand whether temperature regulates GHR gene expressions independently of nutritional state, fish were reared at 8, 12 or 16 8C and either fed ad libitum or with the same ration (1$2% of body weight per day). In the muscle of fish fed ad libitum, a higher rearing temperature increased GHR1 (P!0$001) but not the GHR2 mRNA levels. When the fish were restricted, temperature no longer affected the levels of GHR1 and GHR2 transcript. In the liver of fish fed ad libitum, a higher rearing temperature increased both GHR1 and GHR2 mRNA levels (P!0$001), while in restricted fish, no difference was seen. In conclusion, the two GHR genes are differentially regulated following temperature change and this was related to the period of fish life (embryo or juvenile) and the tissue (liver or muscle). In juveniles, the GHR, by integrating the effect of temperature on plasma GH and nutritional state, could play a key role in the growthpromoting effect of temperature.

Acute heat stress and dietary methionine effects on IGF-I, GHR, and UCP mRNA expression in liver and muscle of quails

“…In addition to environmental temperature (Gabillard et al, 2003(Gabillard et al, , 2006, studies show that the expression of growth-related hormones, such as insulin-like growth factor I (IGF-I) and growth hormone receptor (GHR), may be influenced by other factors, such as nutrition (Katsumata et al, 2002;Gasparino et al, 2012). According to Kimball and Jefferson (2004), amino acids play a key role in regulating some cellular processes, such as the regulation of gene expression by mRNA modulation.…”

Co-expression of IGFs and GH receptors (GHRs) in gilthead sea bream (Sparus aurata L.): sequence analysis of the GHR-flanking region

“…At this standpoint, polyploidy has long been recognized in fish (Zhou et al 2001, Volff 2005, and duplication and divergence offish GHRs would take place on an early ancestor of fish lineage. Salmonids are, however, considered recent tetraploids, and two isoforms of GHR-II are differentially expressed in rainbow trout (Very et al 2005, Gabillard et al 2006. Truncated variants of GHR-I have been characterized in turbot (Calduch-Giner et al 2001) and Japanese flounder (Nakao et al 2004), and this fact might allow the silencing and/or apparent genomic loss of GHR-II in the flatfish lineage (Saera-Vila et al 2005).…”

“…Binding studies in masu salmon evidenced that GH and somatolactin (SL) may functionally interact through GHR-I (Fukada et al 2005). Experimental evidence also indicates that the expression of GHR-II is modulated by water temperature in rainbow trout (Gabillard et al 2006), whereas GHR-I and GHR-II are differentially regulated by cortisol and testosterone in black sea bream (Jiao et al 2006). Previous studies in gilthead sea bream also revealed that duplicated GHRs are differentially regulated by fasting (Saera-Vila et al 2005), although the relative contribution of each gene in the regulation of fish growth still remains unclear.…”

Advances in research on the prenatal development of skeletal muscle in animals in relation to the quality of muscle-based food. I. Regulation of myogenesis and environmental impact

“…In rainbow trout juveniles, the temperature-induced increase in growth rates was associated with high plasma GH and IGF-1 levels (Gabillard et al, 2005). Moreover, the temperature-induced increase in muscle growth was associated with an increase in expression of GH receptor 1 (Gabillard et al, 2006b) suggesting that this receptor has a key role in the response to temperature. In European sea bass, early thermal environments influenced white and red muscle hyperplasia in later stages suggesting the existence of early programming of axial white muscle hyperplasia (Alami-Durante et al, 2006a, 2006b.…”

“…Moreover, the temperature-induced increase in muscle growth was associated with an increase in expression of GH receptor 1 (Gabillard et al, 2006b) suggesting that this receptor has a key role in the response to temperature. In European sea bass, early thermal environments influenced white and red muscle hyperplasia in later stages suggesting the existence of early programming of axial white muscle hyperplasia (Alami-Durante et al, 2006a, 2006b. For example, white muscle hypertrophy was stimulated at 208C and hyperplasia at lower temperatures in embryos, whereas both hypertrophy and hyperplasia were stimulated at 208C in free-swimming larval sea bass (Alami-Durante et al, 2006a).…”