The Effect of Orally Supplemented Melatonin on Larval Performance and Skeletal Deformities in Farmed Gilthead Seabream (Sparus aurata)

Abstract

The gilthead seabream larval rearing in continuous light is common in most Mediterranean hatcheries to stimulate larval length growth and increase food consumption. Several studies have shown that continuous light affects larval development and increases the prevalence of skeletal deformities. Melatonin is a crucial pineal neurohormone that displays daily secretion patterns, stimulates cell proliferation and embryonic development in Atlantic salmon and zebrafish, and improves osseointegration in mice and humans. However, no studies have examined the effects of orally supplemented melatonin on skeletal deformities in Sparus aurata larvae. We administered exogenous melatonin to gilthead seabream larvae via enriched rotifers and nauplii of Artemia. Exogenous melatonin induced bone deformities and stimulated parathyroid hormone-related protein-coding gene (PTHrP) mRNA expression. In addition to the melatonin-induced PTHrP high expression level, the recorded non coordinated function of skeletal muscle and bone during growth can be the fountainhead of bone deformities. Both myosin light chain 2 (mlc2) and bone gamma-carboxyglutamate protein-coding gene (bglap) expression levels were significantly affected by melatonin administration in an inverse dose–response manner during the exogenous melatonin administration. This is the first study to report the effect of inducing melatonin bone deformities on Sparus aurata larvae reared under ordinary hatchery conditions.

Time-Restricted Feeding Could Not Reduce Rainbow Trout Lipid Deposition Induced by Artificial Night Light

“…Similarly, LL caused a higher lower jaw malformation in European sea bass ( Dicentrarchus labrax ) [ 67 ]. In gilthead seabream ( Sparus aurata ), Mhalhel et al (2020) [ 68 ] found that exogenous melatonin supplementation affected normal skeletogenesis and caused bone deformities by regulating the expression of genes related to bone formation. Fish receive external light signals and convert environmental time cues into endogenous biological signals through melatonin secretion [ 53 ].…”

“…Fish receive external light signals and convert environmental time cues into endogenous biological signals through melatonin secretion [ 53 ]. Therefore, the increased bone deformity caused by LL may be related to the loss of coordination between the skeletal muscle and bone function caused by the disturbance of the circadian clock [ 68 ]. Although no bone deformities were observed in juvenile rainbow trout in the LL group, the significantly low whole-body ash and higher lipid deposition may be a warning sign of concern in the metabolic disturbance.…”

Melatonin facts: Lack of evidence that melatonin is a radical scavenger in living systems

“…One of the key points of those claims is the common belief that melatonin has no toxicity. A feature largely controverted for at least 30 years 17 and for which continuous interrogations are published, 18–31 most of which were consistently ignored or disregarded. Even more preoccupying, sentence such as “ Therefore, in view of the lack of toxicity of melatonin, the administration of pharmacological doses of this compound may significantly improve its efficiency as an antioxidant agent .” 32 Incidentally, some have shown that such antioxidant capacity of melatonin does not correspond to the experimental evaluation, for example, of the total antioxidant activity of blood 33 .…”

“…16 One of the key points of those claims is the common belief that melatonin has no toxicity. A feature largely controverted for at least 30 years 17 and for which continuous interrogations are published, [18][19][20][21][22][23][24][25][26][27][28][29][30][31] most of which were consistently ignored or disregarded. Even more preoccupying, sentence such as "Therefore, in view of the lack of toxicity of melatonin, the administration of pharmacological doses of this compound may significantly improve its efficiency as an antioxidant agent."…”

Melatonin Attenuates Dextran Sodium Sulfate Induced Colitis in Obese Mice

“…Cumulative evidence has discussed that melatonin has a wide range of protective effects on various diseases, such as arrhythmia [ 13 ], primary biliary cholangitis [ 14 ], diabesity [ 15 ], non-small cell lung cancer [ 16 ], anovulatory disorders [ 17 ], cutaneous diseases [ 18 ], neurodegenerative diseases [ 19 , 20 ], and autism [ 21 ]. Furthermore, the beneficial effects of melatonin have also been studied in Sparus aurata [ 22 ] and Plasmodium falciparum [ 23 ]. In these studies, melatonin acted as a protector by regulating pathophysiological mechanisms and signaling pathways.…”