Melatonin reduces body weight in goldfish (Carassius auratus): effects on metabolic resources and some feeding regulators

Abstract

The objective of the present study was to analyze the effects of chronic melatonin (10 microg/g body weight) on body weight and the main energetic reserves, particularly hepatic and muscle content of proteins, lipids and glycogen in goldfish. In addition, we studied plasma leptin and ghrelin, and hypothalamic content of neuropeptide Y (NPY) and monoamines after chronic melatonin treatment in order to elucidate a possible interplay between melatonin and these feeding regulators on the body weight regulation in this species. Body weight gain and specific growth rate were reduced (74% and 76%, respectively) after chronic (10 days) intraperitoneal (i.p.) treatment with melatonin. The carbohydrate and lipid metabolism was regulated by melatonin in goldfish, because this indoleamine reduced muscle glycogen stores and increased lipid mobilization. A suppressive trend, but not statistically significant, in circulating ghrelin was observed after chronic treatment with melatonin. Chronic melatonin administration significantly reduced noradrenergic metabolism and increased dihydroxiphenylacetic acid content in the hypothalamus, without significant modifications in the serotoninergic system. Thus, it could be suggested that melatonin may mediate its action on energy balance in fish, at least in part, via interactions with hypothalamic catecholaminergic system. Plasma leptin and hypothalamic NPY remained unaltered after melatonin treatment, suggesting that these feeding regulators may not be involved in the effects of melatonin on energy homeostasis in fish.

Melatonin and Peripheral Circuitries: Insights on Appetite and Metabolism in Danio Rerio

“…mediated by IGF-I, 18,19 and Falcó n et al 20 demonstrated a direct role of melatonin on GH secretion. In addition, recent studies have shown that melatonin influences carbohydrates and lipid metabolism in goldfish liver and muscle 17 ; inconsistent results, instead, were found in mammals. [21][22][23] In this regard, among signals that regulate feeding behavior and metabolism, leptin (LPT) plays a key role as a satiety molecule controlling body weight maintenance.…”

“…7,14 In fish, a contrasting action of melatonin on growth has been observed: a significant weight increase was found in Atlantic salmon implanted with melatonin, 15 while in both trout and goldfish, implants or injections reduced body weight and growth rate. 16,17 On the other hand, it is well known that a central component of growth processes is the growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis. Many of the growth-promoting actions of GH in fish are 1 Dipartimento di Scienze della vita e dell'ambiente, Università Politecnica delle Marche, Ancona, Italy.…”

Role of oleoylethanolamide as a feeding regulator in goldfish

“…Dopamine (DA) and serotonin (5-HT) systems have been found to inhibit food intake, while noradrenaline (NA) stimulates it (de Pedro et al, 1998a;de Pedro et al, 1998b). Moreover, interactions between monoaminergic systems and other feeding regulators have been previously reported in goldfish (de Pedro et al, 1998a;de Pedro et al, 2006;de Pedro et al, 2008).…”

“…The content of NA, DA, DOPAC (a major DA metabolite), 5-HT and 5-HIAA (a major 5-HT metabolite) in hypothalamus and telencephalon were quantified by HPLC (Agilent 1100, Madrid, Spain) with coulometric detection (ESA Coulochem II, Chelmsford, MA, USA) as previously described (de Pedro et al, 2008). Briefly, the tissues were sonicated in 100 μl of cold perchloric acid (0.3 mol l −1 ; Scharlab, Sentmenat, Spain) containing 0.4 mmol l −1 sodium bisulphate and 0.4 mmol l −1 EDTA disodium salt dihydrate (Sigma Chemical).…”

Circadian rhythm of melatonin secretion and growth-related gene expression in the tiger puffer Takifugu rubripes

“…The plasma melatonin level in Mozambique tilapia Oreochromis mossambicus increases during the night and decreases at day (Nikaido et al 2009). Although it has been suggested that melatonin secretions affect physiological functions, including body growth in fish (Taylor et al 2005;Herrero et al 2007;De Pedro et al 2008;Maitra et al 2013), the effect of melatonin on the transcription of growth-related genes (ghrh and ss) is still unclear.…”