REV-ERBα Agonist SR9009 Promotes a Negative Energy Balance in Goldfish

Abstract

REV-ERBα (nr1d1, nuclear receptor subfamily 1 group D member 1) is a transcriptional repressor that in mammals regulates nutrient metabolism, and has effects on energy homeostasis, although its role in teleosts is poorly understood. To determine REV-ERBα's involvement in fish energy balance and metabolism, we studied the effects of acute and 7-day administration of its agonist SR9009 on food intake, weight and length gain, locomotor activity, feeding regulators, plasma and hepatic metabolites, and liver enzymatic activity. SR9009 inhibited feeding, lowering body weight and length gain. In addition, the abundance of ghrelin mRNA decreased in the intestine, and abundance of leptin-aI mRNA increased in the liver. Hypocretin, neuropeptide y (npy), and proopiomelanocortin (pomc) mRNA abundance was not modified after acute or subchronic SR9009 administration, while hypothalamic cocaine- and amphetamine-regulated transcript (cartpt-I) was induced in the subchronic treatment, being a possible mediator of the anorectic effects. Moreover, SR9009 decreased plasma glucose, coinciding with increased glycolysis and a decreased gluconeogenesis in the liver. Decreased triglyceride levels and activity of lipogenic enzymes suggest a lipogenesis reduction by SR9009. Energy expenditure by locomotor activity was not significantly affected by SR9009. Overall, this study shows for the first time in fish the effects of REV-ERBα activation via SR9009, promoting a negative energy balance by reducing energetic inputs and regulating lipid and glucose metabolism.

Keywords: body weight; feeding; fish; glucose; growth; lipids; metabolism; nr1d1.

Figure 1

Effect of acute and subchronic SR9009 treatment on food intake in goldfish (Carassius auratus). (a) Food intake in the intervals of 0−2, 2–8, and 0–8 h after acute IP injection of vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw, n = 9 fish/group). (b) Average daily food intake in the lapse of 2 h during subchronic (7 days) vehicle or SR9009 (100 µg/g bw) IP administration (n = 12 fish/group). Data are expressed as mean + S.E.M. * p < 0.05, ** p < 0.01, *** p < 0.001 SR9009 compared to control group (Student’s t-test).

Figure 2

Effect of subchronic SR9009 treatment on growth of goldfish (Carassius auratus). Relative weight gain (a), specific growth rate (b), and relative standard length gain (c), over the 7 days of the subchronic IP administration of vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw) (n = 12 fish/group). Data are expressed as mean + S.E.M. *** p < 0.001 SR9009 compared to control group (Student’s t-test).

Figure 3

Effect of acute and subchronic SR9009 treatment on hypothalamic feeding regulators. Relative mRNA abundance of hcrt (a,b), npy (c,d), cartpt-I (e,f), and pomca (g,h) in the hypothalamus of goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). The left column shows results of the acute treatment (n = 9 fish/group), and the right column of the 7-day subchronic treatment (n = 12 fish/group). Data are expressed as mean + S.E.M. in relative units (2^−ΔΔCt). * p < 0.05 SR9009 compared to control group (Student’s t-test).

Figure 4

Effect of acute and subchronic SR9009 treatment on peripheral feeding regulators. Relative mRNA abundance of ghrelin (a,b) and leptin-aI (c,d) in the intestine and liver, respectively, of goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). The left column shows results of the acute treatment (n = 9 fish/group), and the right column of the 7-day subchronic treatment (n = 12 fish/group). Data are expressed as mean + S.E.M. in relative units (2^−ΔΔCt). * p < 0.05, ** p < 0.01 SR9009 compared to control group (Student’s t-test).

Figure 5

Effect of acute and subchronic SR9009 treatment on plasma levels of glucose (a,b), fatty acid (c,d), and triglyceride (e,f) in goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). Data are expressed as mean + S.E.M. (acute, n = 9/group; subchronic, n = 12/group). * p < 0.05, ** p < 0.01 SR9009 compared to control group (Student’s t-test).

Figure 6

Effect of acute and subchronic SR9009 treatment on liver metabolites. Hepatic glucose (a,b), glycogen (c,d), fatty acid (e,f), and triglyceride (g,h) in goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). Data are expressed as mean + S.E.M. (acute, n = 9/group; subchronic, n = 12/group). * p < 0.05 SR9009 compared to control group (Student’s t-test).

Figure 7

Effect of subchronic SR9009 treatment on enzymes related to glucose metabolism. Activity of enzymes related to glycolysis (a–d), glucose anabolism (e–g), and pepck mRNA abundance (h) in the liver of goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). Data are expressed as mean + S.E.M. (n = 12/group). ** p < 0.01, *** p < 0.001 SR9009 compared to control group (Student’s t-test).

Figure 8

Effect of subchronic treatment SR9009 on the activity of enzymes related to lipid metabolism. Activity of ATP citrate lyase (a), fatty acid synthase (b), and carnitine palmitoyltransferase 1 (c) on the liver of goldfish (Carassius auratus) treated with vehicle alone (CONTROL) or containing SR9009 (100 µg/g bw). Data are expressed as mean + S.E.M. (n = 12/group).